ArticlePDF Available


On the morning of September 11th, 2001, the United States and the Western world entered into a new era - one in which large scale terrorist acts are to be expected. The impacts of the new era will challenge supply chain managers to adjust relations with suppliers and customers, contend with transportation difficulties and amend inventory management strategies. This paper looks at the twin corporate challenges of (i) preparing to deal with the aftermath of terrorist attacks and (ii) operating under heightened security. The first challenge involves setting certain operational redundancies. The second means less reliable lead times and less certain demand scenarios. In addition, the paper looks at how companies should organize to meet those challenges efficiently and suggests a new public-private partnership. While the paper is focused on the US, it has worldwide implications.
Massachusetts Institute of Technology
Engineering Systems Division
Working Paper Series
ESD-WP-2003-01.27-ESD Internal Symposium
Yossi Sheffi
Professor of Engineering Systems
Professor of Civil and Environmental Engineering
Massachusetts Institute of Technology
MAY 29-30, 2002
Supply Chain Management under the Threat of
International Terrorism
Yossi Sheffi
Professor of Engineering Systems
Professor of Civil and Environmental Engineering
Massachusetts Institute of Technology
MIT Center for Transportation and Logistics
Rm 1-235
77 Massachusetts Avenue
Cambridge, MA 02139
This paper was published in the April 2002 issue of the
International Journal of Logistics Management
Supply Chain Management under the Threat of
International Terrorism
On the morning of September 11th, 2001, the United States and the Western world
entered into a new era – one in which large scale terrorist acts are to be expected. The
impacts of the new era will challenge supply chain managers to adjust relations with
suppliers and customers, contend with transportation difficulties and amend inventory
management strategies.
This paper looks at the twin corporate challenges of (i) preparing to deal with the
aftermath of terrorist attacks and (ii) operating under heightened security. The first
challenge involves setting certain operational redundancies. The second means less
reliable lead times and less certain demand scenarios. In addition, the paper looks at how
companies should organize to meet those challenges efficiently and suggests a new
public-private partnership. While the paper is focused on the US, it has worldwide
The author is indebted to Dr. Jim Masters and Mr. Dan Dolgin who provided invaluable
insights and detailed comments, including extensive editing. Three anonymous referees
also provided helpful comments.
The Challenge
Within days of the September 11, 2001 terrorist attack, manufacturers began to
experience disruptions to the flow of materials into assembly plants. For example, Ford
had to idle several of its assembly lines intermittently as trucks loaded with components
were delayed at the Canadian and Mexican borders. Toyota came within hours of halting
production at its Sequoia SUV plant in Indiana, since a supplier was waiting for steering
sensors shipped by air from Germany, but air traffic was shut [1]. Ford, Toyota, and
other manufacturers were vulnerable to transportation disruptions because they operate a
“Just-in-Time” (JIT) inventory discipline, keeping material on hand for only a few days
and sometimes only a few hours of operation.
It is instructive to note that these disruptions were not caused by the attack itself, but
rather by the government’s response to the attack: closing borders, shutting down air
traffic, and evacuating buildings throughout the country. The federal government is now
readying its thinking, its institutions, its communications strategy, its military response,
and its domestic defense strategy for a challenge of fighting terrorism, that is likely to last
a long time.
Popular wisdom repeatedly recites that the war on terrorism is unlike any past war. But
popular wisdom has not yet adapted to the most fundamental way in which this "war" is
different. In fact, it is not so much a war as it is a new era of continuous danger. In
addition, the defensive aspects of this war will be fought on the home front, not by a
professional army but by business organizations and ordinary citizens endeavoring to
make the interdependencies of our economy function for their own benefit, not as the
weapons of the enemy.
As companies organize to face this new era, manufacturers, distributors, retailers and
other firms involved in the handling of physical goods face four challenges:
1. Preparing for another attack. Assuming that some future attack will be successful,
companies must prepare to operate in its aftermath. Firms are vulnerable not only
to attacks on their own assets, but also to attacks on their suppliers, customers,
transportation providers, communication lines, and other elements in their eco-
2. Managing supply chains under increased uncertainty. Measures taken by the US
and other governments to improve homeland defense have burdened the global
transportation system, creating longer and less reliable lead times. In addition,
even small terrorist events, which have negligible economic consequences in
themselves, can have disproportionate effects on demand.
3. Managing relationships with the government. The war on terrorism will bring
about a new era of public-private cooperation in which companies will reform
their relationships with the government. All US citizens and business
organizations will have a part to play in this war.
4. Organizing to meet the challenge. Actions taken to defend employees, physical
assets, and intellectual property will consume resources. Companies must
determine what to do, and how to do it in the most efficient manner, balancing the
costs and benefits of security needs against other corporate goals.
Preparing for Another Attack
One of the main tenets of military preparedness is the investment in redundancy, which
can hardly be justified on the basis of its positive net present value. Preparedness is best
viewed as insurance. We use this framework to analyze investments in three main
categories: (i) supplier relationships and awards, (ii) inventory management criteria, and
(iii) knowledge and process backup.
Supplier relationships
During the last decade many companies reduced the number of their suppliers,
developing “core supplier” programs in order to create stronger relationships with fewer,
key suppliers. A counter trend took hold in the late 1990‘s with the Internet boom. E-
procurement tools and services enable companies to conduct on-line auctions and
participate in commodity exchanges, expanding the number of firms with whom they do
business and decreasing costs.
Security considerations are likely to push more companies to abandon public exchanges
in favor of private auctions (where only known and pre-screened suppliers are allowed to
participate), or to abandon auctions altogether in favor of long-term relationships with
suppliers. In the new era companies may worry that their suppliers will ration their output
in case of a disruption. Clearly, suppliers are likely to allocate products first to customers
with whom they have long-term relationships, giving this type of relationships added
value in the new environment.
Since September 11, many US (as well as European) companies are reconsidering the
wisdom of using overseas suppliers. Offshore suppliers may be less expensive, but
require longer lead-time and may be more susceptible to disruptions in the transportation
system. Local suppliers may be more expensive but are closer and therefore able to
respond faster.
Instead of choosing one alternative over another, the best solution may include both –
using offshore suppliers for the bulk of the procurement volume while making sure that a
local supplier has the capability to fill the needs, by giving it a fraction of the business. In
the terminology of insurance, the incremental cost of using the local supplier is the
premium paid for the reduced risk of supply-chain disruption.
Consider the following example: a high technology company sells medical devices made
by a contract manufacturer in Malaysia. The Malaysian supplier delivers the devices at
$100 a piece and the devices are sold by the US company at $400 each. Fixed costs,
including marketing and channel setup, have been estimated at $200 per device. Thus, the
company expects a profit of:
P1 = $400 - $100 - $200 = $100 per device.
The company estimates that there is a 1% probability that the Malaysian supplier will be
disrupted and will not be able to deliver for an extended period. This will expose the
company to $200 loss per device since in case of a disruption the company will have no
sales but will still be burdened with the fixed costs. Taking this into account, the expected
profit when using the Malaysian supplier is:
P2 = 0.99*($400 - $100) - $200 = $97 per device,
A local supplier can deliver the same devices for $150 each. Under a dual supply
arrangement the local supplier may be given a portion, say 20% of the business if it
guarantees to supply all of the company’s requirements should the need arise. If there is
no disruption, then, the expected profit when using dual manufacturing will be:
P3 = $400 - (0.8*$100 + 0.2*$150) - $200 = $90 per device
If there is a disruption, the local manufacturer will supply the devices and the company’s
profit will be:
P4 = $400 - $150 - $200 = $50 per device
Taking into account, however, that in case of a disruption the company will be able to use
the local supplier, the expected profit when operating with dual suppliers is:
P5 = 0.99* P3 + 0.01* P4 = $89.6 per device
Dual manufacturing will cost the company $7.4 per device (P2 – P5) in expected profit.
This is the insurance premium. The value of the insurance is that if a disruption does
occur, the company will experience a profit of $50 instead of a loss of $200 per device.
This simple example ignores the time value of money, possible penalties for not
delivering and many other aspects of reality. It demonstrates, however, the value of
purchasing the insurance.
Thus, one can expect some jobs to be moving back into the US, as companies trade off
lower parts costs against delivery reliability. This shift, however, is likely to be neither
large nor immediate. It is unlikely that companies will forgo the benefits of low cost, high
quality offshore manufacturing altogether, but rather will only hedge their bets with local
suppliers. Calculation of the insurance value depends largely on assessment of the
probability of a disruptive event. Even after a decision to dual-source is made, it will
take time since sourcing decisions are often made several years in advance of product
launch. The first signs of such strategies should be seen in the high technology sector
with its short product life cycle and traditionally high reliance on offshore contract
Note that dual supply sources are not a new idea and they have general merits beyond
responding to terror. For example, Billington and Johnson [2] describe how Hewlett
Packard has used “dual response manufacturing” to supply inkjet printers to North
America for several years. It used a Vancouver, Washington supplier to launch the
product and deal with demand peaks, while a low cost Singaporean supplier handled most
of the stable production.
In response to the terrorist attack of September 11, companies began to question the
wisdom of “lean operations” using JIT processes. Some companies are ordering parts in
larger quantities, increasing safety stocks to keep their assembly lines moving “just in
case” their inbound transportation is disrupted. In addition, they plan to keep more
finished goods on hand so customers can be supplied even when the manufacturing
process is disrupted.
The benefits of JIT manufacturing, however, have been immense. Manufacturers not only
have seen their inventory carrying costs go down -- even more importantly, they have
seen their product quality improve dramatically. With a JIT system, component quality
problems are apparent and must be resolved. This discipline is one of the underlying
principles of the Toyota Manufacturing System, which has been adopted, in one form or
another, by leading manufacturers in every industry.
The challenge then is to ensure that supply lines are maintained while not incurring the
high costs of extra inventory. A possible solution, which can again be analyzed by using
the insurance framework, is to separate the normal business uncertainties from the risk
associated with another possible terrorist attack, creating, in fact, a “dual inventory”
system. Under this system, typical forecasting discrepancies and business fluctuations
should be covered by conventional safety stock.
To mitigate the effect of another terrorist attack, however, manufacturers should maintain
an additional inventory designated “Strategic Emergency Stock.” This stock is not used
to buffer day-to-day fluctuations. It can only be used in the case of an extreme disruption.
The costs of carrying this extra inventory represent the price of the premium for the
insurance it buys.
It is unreasonable to expect managers to ignore this inventory when a service failure takes
place in normal times. To make sure that the organization will not simply become
accustomed to the higher level of inventory, two policies should be adopted: First, the
strategic inventory should be replenished immediately in a “Sell-One-Store-One (SoSo)”
discipline regardless of daily forecasts. Second, usage of the strategic inventory should be
treated in the same way that assembly line shutdowns are treated. In other words, it
should get top management attention and the root causes fixed at the source.
The concept of Strategic Emergency Stock is similar to the philosophy that led the US to
keep Strategic Oil Reserves, which are intended to buffer the US against a severe
disruption in the flow of oil. When these reserves have been used to moderate oil price
spikes, they have been promptly replenished in order to maintain their availability for
their primary purpose. A similar “strategic inventory” of certain key medicines is kept by
hospitals for use in crisis situations.
Knowledge Backup
The preparations involved in protecting companies’ knowledge involve three main
efforts: (i) developing backup processes (ii) backing up the company’s knowledge, and
(iii) backing up the company’s relationships.
Many companies have long understood their total reliance on their information
technology infrastructure and have established backup sites for their critical hardware,
software applications, and data
Consider, for example Solomon Smith Barney. The financial services firm had 7,000
workers in the World Trade Center, all of whom, fortunately, got out in time. The
company was up and running within twelve hours using a backup New Jersey site and
invoking a set of emergency backup processes.
Few companies, however, have backup emergency business processes. Such processes
spell out communications protocols, chains of authority, and decision-making procedures
in case of damage to systems, losses in personnel and breakdown in communications.
More generally, the most precious resource of nearly every company is the knowledge of
its workers. Since companies cannot afford to maintain redundant employees around “just
in case,” companies should insure that their knowledge is backed up. This means that
critical processes should be documented and that these documents are available. When
appropriate, cross training should be part of any preparedness effort.
Many companies document business processes when they are designed, but fail to keep
up with their ever-changing nature as these processes mutate in actual use. This failure
may be the impetus for a much better set of software applications, which support both the
processes and their continuous documentation.
In addition to business processes, companies need to be able to salvage customer and
supplier relationships. These can be protected if all interactions with customers have been
documented in a Customer Relationship Management (CRM) system. Relationships
should be deemed just as important as data and processes. Documenting all customer
interactions can help companies pick up after a disaster much quicker.
* * *
All of these backup activities are a form of insurance premium. Not every preparedness
action, however, imposes a premium. Some strategies are beneficial to the business at any
time but take on extra significance when looked upon from the perspective of
preparedness. One such notion is standardization. One of the most important tools in
creating redundancy and the ability to recover quickly is standardization of business
processes and practices across the enterprise. To this end, corporations with several
warehouse management systems, multiple order entry systems, or several incompatible
manufacturing and financial systems, are more vulnerable than companies who
standardized their operations and can move personnel and processes between locations if
a single location goes down.
Managing Supply Chains Under Increased Uncertainty
Manufacturing supply chains involve a network of enterprises and processes, which turn
a combination of raw materials into finished products delivered to the consumer. Most
anti-terrorist measures will reduce the reliability of the network, challenging supply chain
management processes.
Longer supply lines and system uncertainties are not new problems for supply chain
managers. The globalization of manufacturing, the explosion of new products, and
shortened product life cycles have burdened logistics managers with long supply lines
and significant demand uncertainty. In that sense, the new era does not represent a
fundamentally new challenge. Thus, the basic problem can be tackled by refocusing on
known solutions, including (i) improvements in shipment visibility, (ii) improved
collaboration between trading partners and across enterprises, and (iii) better forecasting
through risk pooling methods.
Shipment Visibility
Many logistics managers still describe their transportation system as a “black hole” –
shipments disappear when tendered to the carrier and no information is available to either
shipper or consignee until the shipment is delivered. Shipment visibility tools allow
shippers to track the progress of their shipments in the same way that consumers can
track the flow of their UPS or FedEx shipments. Tracking industrial shipments has
proved to be a significantly more challenging problem – it involves multiple carriers and
“hand-offs,” and it requires integration with manufacturing, inventory and purchasing.
Furthermore logistics managers deal with thousands of items every day and they need to
know not only what is in-transit, but also what is available in stock, what is on-order, and
when orders will be available from suppliers.
Shipment data visibility allows manufacturers to avoid plant shutdown due to part
shortages and allows retailers to avoid turning customers away due to unavailability of
goods. At the same time, good visibility also allows all the players in the supply chain to
keep lower safety stocks since the demand pattern they experience will be more stable
and their suppliers will be more consistent. The cost savings associated with better
forecasting and smoother operations include not only lower inventory carrying costs, and
the avoidance of expedited shipments; it also means that warehousing facilities can be
downsized and a significant amount of administrative overhead associated with
unscheduled activities can be avoided.
There are several partial technology solutions available today for helping shippers find
out where their shipments are, as well as helping them decide what action to take in case
a shipment is late, misrouted, damaged, or otherwise in trouble. Some of these solutions
are available from carriers who are tracking their own conveyance movements, while
others are available from software providers who are attempting to aggregate the
information from many carriers, suppliers and their own warehouses and present it to
shippers in an integrated fashion.
To date, most shipment tracking information is based on following the conveyance that a
shipment is using or the shipment’s location and status. Accurate tracking depends on
timely reporting from the carriers hauling the shipment, the warehouseman storing it, or
the distributor handling it. This is true for all short-range technologies (including all bar
codes and RF devices). New technology using tags which can communicate directly with
low-earth-orbiting-satellite (LEOS) systems offers the promise of freeing consignees
from their reliance on carriers and other suppliers by allowing direct communications
with the shipment.
As lead times are becoming longer and less consistent, shippers should mitigate the
problem by investing in visibility tools. Even in cases in which these tools provide only a
partial coverage, they help moderate the problems by allowing timely responses.
Improved Collaboration
The focus of supply chain management is on interactions between enterprises in the
chain. Collaboration among enterprises is what integrates the supply chain.
Since the mid 1980s, American companies have devised many cooperative schemes to
improve supply chain coordination. These include vendor-managed-inventory (VMI) and
co-managed inventory (CMI) in the retail industry, efficient consumer response (ECR) in
the grocery industry, quick response (QR) in the textile industry, just-in-time (JIT) in
manufacturing, and JIT II in high-technology procurement. Lately, collaborative
planning, forecasting and replenishment (CPFR) is taking hold in the consumer packaged
goods industry and collaborative transportation management (CTM) is under
development for the transportation industry. These and dozens of other such initiatives
are aimed at ensuring that trading partners share information and coordinate forecasts and
replenishment orders, thus avoiding the unnecessary inventory fluctuations, often referred
to as the “bullwhip” effect, which arise from uncoordinated channel decisions. (The
bullwhip effect is described by Lee et al [3], based on Sterman [4] and [5] and on
Forrester [6].)
The Internet and electronic commerce in particular have enabled new collaborative
processes between companies with the development of new standards, which allow more
flexible and general computer-to-computer communications. New application software
hosted by third party providers allows many trading partners to access their collaborative
data simultaneously.
As lead times are becoming more variable and forecasts less certain, companies should
redouble their collaboration efforts. When the consignee knows about a problem early
enough, it can take corrective measures (expedite shipment, go to an alternative source,
adjust its own customer’s expectations, etc.)
In addition to collaborating to improve supply chain performance, companies should
work both with trading partners and with industry groups to develop best security
practices and share growing expertise. More than ever, corporations should realize that
their long-term fate is intertwined with that of their suppliers, customers, and even their
competitors. Such collaboration has many precedents and is not limited to collaboration
among US companies. For example, when the supremacy of the lean manufacturing and
JIT became apparent, leading Japanese manufacturers, such as Toyota, allowed
researchers from the world over to study their methods. In addition, they allowed other
companies, including competitors, to visit their plants and study their manufacturing
systems. (See, for example, Womack et al [7].) This is an example of the level of
collaboration that will be required in the coming era.
Risk Pooling
One of the fundamentals of forecasting is that forecasts of more aggregate phenomena are
more accurate. For example, forecasts of nationwide sales figures are more accurate than
store level forecasts and monthly forecasts are more accurate than daily forecasts. To
take advantage of this, firms employ a variety of strategies such as:
Postponement. By delaying the decision to make, configure, label, or ship a
product to a particular destination, companies can reduce their forecasting error.
For example, Billington and Johnson (2000) report that Hewlett-Packard cut
printer supply costs by 25 percent with modular design and postponement.
Generic printers are shipped to distribution centers worldwide, where local
customization (involving local transformers, power cords, and instruction manuals
in local language) takes place once firm orders are at hand. Thus, HP forecasts the
aggregate demand for the generic printer, while requiring a disaggregate forecast
only for the local parts which are less expensive to stock and can be acquired with
short lead-times.
Build-to-order. The ultimate postponement strategy is to build items only after
customer orders are known. Dell Computer has used this strategy to become the
world’s dominant PC maker. But even automobile manufacturers are embracing
the strategy. For example, VW now delivers many of its models to German
customers within two weeks of ordering. This means that VW has very few cars
waiting for sale in dealers’ showrooms.
Product variability reduction. Some manufacturers have combated forecasting
difficulties by reducing the number of options and items they offer. For example,
many automobile manufacturers stopped offering all possible combination of
features on their products and put forward “packages” of features instead. The
smaller number of options allows for better risk pooling, lower variability and
thus better forecasts and lower overall costs.
Centralized inventory management. By managing inventory centrally, companies
can use surpluses in one area of the country to cover for deficits in others. This is
another example of risk pooling by geographical aggregation. Thus the trend
towards reducing the number of warehouses and other inventory stocking
locations may accelerate as part of companies’ learning to operate in even more
uncertain times.
Public-Private partnership
US executives often look at many government functions as hindrance to the smooth
operation of the economy. Defense, however, is one of the few roles virtually no one
wants the government to leave undone. In fact, the creation of an Army and a Navy were
contemplated in the US constitution itself.
The US government has taken the first step in organizing for the new environment by
establishing the Office of Homeland Defense. At this point, the office is charged with
coordinating the efforts of the various defense, intelligence, emergency response, health
services and related agencies. The challenge is enormous, but the government is slowly
rising to meet it. Protecting private interests, however vital to the nation, is still the
purview of the owners of those private assets.
Sharing information
Recognizing the important role that government will play in the new era, and recognizing
that government cannot do it alone, corporate executives need to start considering the
government, both federal and local, as a partner in corporate life. Some possible
collaborative avenues include the following:
Use of the vast government know-how on the nature of threats and ways to deal with
them. At the same time, corporations who may be subject to attacks have an
obligation to inform local law enforcement and rescue agencies about their
vulnerabilities. Companies in particularly sensitive businesses, such as nuclear power
generation and chemical manufacturing are already subject to laws that require them
to do so. In the new era, corporate executives should consider possible threats and
work with local authorities even when they are not legally obligated to do so.
Many American corporations have operations all over the world and may possess
information that is important to the national defense. Following the Cold War
tradition, many corporations and individual executives may increase the level of
information sharing with the US government.
Assuming security roles and responsibilities
The US has started to settle into a new long-term reality. This reality is marked by added
security costs, added administrative costs, and longer, as well as less certain
transportation times. Currently, however, the nation has not yet developed new long-term
procedures that will be necessary to deal with the threats efficiently. The delays shippers
and carriers experience today will be reduced as the US develops a more sustainable
security system. Thus, firms should not yet over react to current transportation delays and
added administrative costs.
At this point, the philosophy behind cargo security checks mirrors airport checks in the
US – inefficient and not very effective. By and large, US checkers at airports give the
same level of attention to every passenger who goes through the system. In contrast,
leading airports in Europe and Israel have always used an advanced “profiling” system to
pre-screen, conduct quick interviews and then check more thoroughly certain passengers,
while letting others go through.
Similarly, many of the current processes used to insure the security of freight flows are
inefficient and do not “scale” up. The cost of stopping and checking all trucks at the
Mexican or Canadian border or at a city's limits is unsustainably high.
The freight equivalent of “profiling” is the use of certified carriers and shippers. Current
government efforts are aimed at carriers with whom cargo liability lies. These carriers
will have to be certified, based on training and a prescribed set of security processes. In
addition, shippers should be certified as well for having approved security processes in
place. Thus, for example, trucks owned by “certified carriers” hauling shipments from
“certified shippers” may be waved through check-points (or just spot-checked). The idea
of certifying the source (warehouse, plant, etc.) where a shipment is packaged is foreign
to current regulations, which are aimed at carriers. As US businesses have learned from
the quality movement, however, acting at the source can be both more efficient and more
A version of this idea is included in FAA Directive 108-01-10 and its more recent “Cargo
Revised Emergence Amendment.” The FAA attempts to distinguish between “known
shippers” and “unknown shippers” in setting up procedures for acceptance of cargo by air
carriers. The FAA does not address carrier certification since it is already familiar with
all the air carriers. The problem of certifying carriers is most acute in the trucking
Corporations will take upon themselves some of the burdens of providing security.
Shippers will be responsible for checking and sealing trailers at the origin, as well as
checking the background of their transportation managers and warehouse and
dockworkers. Carriers will develop security procedures for routing and scheduling
sensitive cargo and check the background of all their employees. In addition, certified
carriers will have the ability to track each of their vehicles at any point in its journey and
be automatically alerted if the journey pattern changes.
Leading carriers and shippers should work with the government on the creation of the
certification program. Such certification programs are similar in nature to the ISO 9000
programs used to certify quality. In fact, the government may choose to relegate the
certification to private organizations, creating a structure similar to the quality programs.
Interestingly, US Customs Commissioner Robert Bonner laid out a vision of a similar
system in a speech at an importers conference on November 27, 2001. He suggested a
government security certification program similar to the ISO 9000 quality certification
process. Companies will be able to use a “fast lane” to enter the US if, for example, they
will have certifiably secure processes at their loading docks and their offshore suppliers
plants, if they share the cargo information with the customs service in a timely fashion, if
they use electronic seals on their containers, etc. [8].
Hazardous materials
More than 800,000 hazardous materials shipments move every day in the US alone, 94%
of which are moved by truck. The transportation of hazardous materials deserves special
attention in the fight against terror. The main elements of the existing system are:
The Emergency Planning and Community Right-to-Know Act require that detailed
information about hazardous substances in or near communities be available at the
public's request.
The U.S. Department of Transportation employs a labeling and placarding system for
identifying the types of hazardous materials that are transported along the nation's
highways, railways, and waterways. This system enables local emergency officials to
identify the nature and potential health threat of chemicals being transported.
In 1986, Congress passed the Superfund Amendments and Reauthorization Act
(SARA) of 1986. Title III requires that each community establish a Local Emergency
Planning Committee (LEPC) to be responsible for developing an emergency plan for
preparing for and responding to chemical emergencies in that community. The LEPC
is required to review, test, and update the plan each year.
The systems that are in place are aimed at efficient response to an accident involving
hazardous material. Proposed new legislation increases fines for non-compliance and
strengthens the US Department of Transportation inspectors’ authority to inspect cargo in
transit. Separate legislation is aimed at tightening the rules for obtaining commercial
drivers’ licenses.
These legislative moves are appropriate and timely. The threat of terrorism calls for
further control of the movements of hazardous materials so that the authorities can react
after a trailer-load or a rail car loaded with hazardous materials is reported missing but
before it is used in a terrorist attack. To this end the US may create a “HazMat
Transportation Control System” similar to the air traffic control. Before trucks or rail cars
will be allowed to depart they will file a “flight plan” and then be tracked to that plan
throughout their journey. Deviations from the plan can be checked.
Direct Emergency Assistance
Modern, large corporations have access to extensive resources, which in many cases rival
public resources. Some of these resources may have to be used as part of the homeland
defense effort during wartime.
This idea is not new; for example, US sealift strategy includes the use of the Merchant
Marine fleet in case of war according to the Merchant Marine Act of 1936. The Civil
Reserve Air Fleet (CRAF) was similarly established to organize civilian airliners to
augment regular military airlift capability in a military emergency.
Corporations should get ready to join in the national defense and in the rescue and
recovery efforts that will follow. The corporate function that can provide the most help is
logistics and transportation management. Logistics professionals should organize in every
area of the US to prepare and help FEMA, the Red Cross and other agencies charged with
alleviating emergencies and rebuilding affected communities. Most of these preparedness
efforts involve the creation of local databases regarding the availability of transportation
capacity to haul people and materiel; heavy earth moving and construction equipment;
warehouse space and shipping and handling equipment; computers and communication
hardware; etc.
Organizing to meet the Challenge
Many of the actions required for security and preparedness are in conflict with traditional
corporate goals and processes. Consider, for example, the following trade-offs:
Repeatability vs. unpredictability. In order to be successful and reduce the cost of
performing their everyday activities, companies establish repeatable processes.
Doing the same task over and over again means that workers get good at it, it is
easy to measure and “perfect,” and easy to manage. In fact, when processes differ
from the norm, companies generate another process to deal with exceptions – in
an attempt to standardize even the outliers.
Many aspects of security, however, require that companies be less predictable.
For example, daily changes to the route that a truck carrying hazardous material is
using, or frequent changes to password systems and other entry control systems to
computers and facilities increases security.
The lowest bidder vs. the known supplier. To enhance security, companies may
choose to deal with fewer suppliers on a long-term basis (as mentioned in the
section Supplier relationships), but there might be substantial costs incurred in
doing so. New suppliers often offer more competitive prices and they may bring
with them new ideas and innovative processes. The same rationale applies to the
choice of local vs. overseas suppliers discussed in that section.
Centralization vs. dispersion. In order to pool the forecasting risk, companies
should manage inventory centrally (see the Inventory section). Indeed, many
corporate activities, from the provision of information technology to office work,
are conducted better in a central location. Security considerations, however, call
for dispersion of both assets and personnel in order to mitigate the effect of any
local terrorist attack.
Managing risk vs. delivering value. The costs associated with new security
measures are likely to be significant. The success of such measures cannot be
measured by the value they deliver to customers, employees or shareholders day
in and day out. Instead, these measures will be most successful if they are never
actually tested. Consequently, it will be difficult to keep vigilant and keep
investing in assets, personnel, inventory and processes that do not deliver value in
the short term.
Collaboration vs. secrecy. Increased collaboration among enterprises makes
supply chain management more efficient and avoids some of the increased costs
of longer and less certain lead times and demand patterns (see the section
Improved Collaboration). One of the tenets of security, however, is secrecy.
While corporations may be exposing more of their data and internal workings to
others and even sharing information about security measures with other
corporations, they have to do so without compromising security.
Redundancy vs. efficiency. The preparatory steps that corporations may be taking
regarding procurement policies, inventory management and knowledge backup
(see the section Preparing for Another Attack), involve the creation of
redundancies in the system – be it extra supplier capacity, extra inventory, backup
equipment and processes, etc. Such redundancies are, by their very nature, in
direct conflict with “lean operations.” Redundancy calls for a “just in case”
mentality while modern operations are organized around “just in time” systems.
As argued in at the end of this section, the challenge in creating the required
redundancies is to minimize their adverse effects and possibly, use them to create
Government cooperation vs. direct shareholder value. Many US executives are
conditioned to put near-term shareholder value above all other considerations.
The new environment may require cooperation with government and other
companies, including competitors, even at the expense of short-term profit and
near-term shareholder value.
Just as the US has created an Office of Homeland Security, companies will often find it
necessary to create a new office headed by a “Chief Security Officer” (CSO). The CSO
must be, first and foremost, a businessperson who is familiar with the enterprise and in
getting things done in a corporate environment. Organizations, perhaps like individuals,
are subject to a strong temptation to return to normalcy. They gravitate toward return to
the days when nobody had to worry about terrorism and bio-attacks. The CSO and the
security organization will have to continuously fight this temptation. They will face many
of the trade-offs mentioned above on a daily basis, and will have to create the
constituency to follow through with the required investments and changes to corporate
life. Military or law enforcement background may not be the right mix for CSO
candidates. Outsiders may be quickly marginalized in a corporate environment, unless
they can understand the business itself and the trade-offs it routinely makes and argue for
just the required measures and no more, while taking into account the normal business
mission and objectives.
The CSO should be the place in the organization where the various security schemes will
be coordinated and tested, making sure that the enterprise can continue after an attack and
that the emergency processes complement each other. For example, while it is clear that
dispersion of work and personnel is a reasonable strategy to contain damage from
physical terrorist attack, this strategy makes the enterprise more vulnerable to an Internet
virus or worm attack that will impede communications and distributed applications.
Another major business-preparedness role, which the CSO office should coordinate, is
the use of simulation and optimization models to test various scenarios. Such models are
readily available and can be adapted to contingency planning in terms of operating partial
networks, using different ports of entry, responding to massively different demand
scenarios, and adapting warehousing strategies to changing conditions.
The CSO’s task, however, is much bigger than establishing and testing contingency
plans. No Chief Security Officer or security organization will be successful unless the
culture of the enterprise adds security consciousness to its daily life. Thus, companies
that will best survive terrorist attacks will be those whose employees have internalized a
set of intelligent applications of security measures and the needed backup emergency
processes. In that sense, the security challenge is similar to the drive to create a sales
culture during the 1970s and the quality challenge of the 1980s.
Efforts aimed at security can actually improve corporate performance and the preparation
should be put in place with an eye towards reaping such “collateral benefits.” For
example, better security measures can help reduce theft, embezzlement, and loss of
intellectual property. They can help cement relationships with trading partners and
accelerate the work of standard-setting organizations. Participation in community-wide
efforts can also help the corporate image. Beyond the image, however, such efforts can
empower employees and inject new meaning to their jobs, as strong corporations will be
seen not only as a source of economic security to individuals but also as contributors to
the greater good of the nation.
Summary and Conclusions
Terror is not a new world phenomenon and the US itself was no stranger to either suicide
bombing or terrorist plots or attacks, especially in the last decade. The September 11
attack demonstrated, however, the magnitude of the struggle in the new era and its far-
reaching dimensions.
While European governments are in support of the US war on terrorism, it is the US that
is the target of the current wave of terrorism and it is the US who is leading the charge
against it, thereby exposing itself to retaliations.
This struggle will challenge not only the armed forces of the US and its intelligence and
law enforcement institutions, but it will change the way citizens in the Western world
lead their lives and the way corporations conduct their business. This paper had focused
on the last point – getting back to business in the new environment: cooperating with the
government and adding security measures in order to prevent new attacks from taking
place; creating redundancies so that enterprises can withstand such attacks; and changing
corporate processes to cope with the heightened security environment.
[1] Wall Street Journal “As Security Worries Intensify, Companies See Efficiencies
Erode,”, Ip, G., WSJ p. 1, Sep 24 (2001)
[2] Billington, C. and B. Johnson “Creating and Leveraging Options in the High
Technology Supply Chain,” Journal of Applied Corporate Finance, Forthcoming
[3] Lee, H., P. Padmanabhan, and S. Whang, “The Paralyzing Curse of the Bullwhip
Effect in a Supply Chain,Sloan Management Review, Spring (1997), pp. 93-102.
[4] Sterman, J.D. “Modeling Managerial Behavior: Misperceptions of Feedback in a
Dynamic Decision Making Experiment,” Management Science, Vol. 35, No. 3, (1989),
pp. 321-339.
[5] Sterman, J.D., “Misperceptions of Feedback in Dynamic Decision Making,”
Organizational Behavior and Human Decision Sciences, Vol. 43, No. 3, (1989b),
[6] Forrester, J.W., “Industrial Dynamics: A Major Breakthrough for Decision Makers,”
Harvard Business Review, Vol. 36, No. 4, (1958), pp. 37-66.
[7] Womack J., D. Jones and D. Roos The Machine that Changed the World: The Story
of Lean Production, Rawson Associates Press, (1990).
[8] O’Reiley, J., “Under Pressure,” Inbound Logistics October 2001, (2001), pp. 62 - 65
... Strictly Horizontal: Introducing collaboration of two or more supply chain members to proffer solution to a known disruptive event such as a pandemic. [117], [56], [62], [130], [132], [159], [161], [100], [134], [155], [158], [55], and [54] The Hybrid approach was applied by most of the researches cited in this category. The hybrid approach is the combination of proactive and reactive methods. ...
... [65], [59], [127], [167], [169], [31], [32], [15], [8], [179], [180], [133], [132], [25], [133], [160], [17], and [159] Thematic and Systematic review. ...
p>The COVID-19 crisis has attracted attention worldwide to the supply chain disruptions and resilience. Several supply chain risk management approaches have been revisited or reapplied such as collaborative resource sharing. This study aimed to investigate the current academic state of art and advances in using collaborative resources sharing as a reactive method to facilitate supply chain recovery in the presence of disruptive events. More specifically we considered the role of different collaborative resource sharing strategies that organizations can adopt to support supply chain functionalities during times of disruption. We conducted a systematic literature review (SLR) to analyze academic articles that were published online from 2000 to 2022. In order to analyze the literature, we adopted a combination of text-mining, automatic and manual categorization of selected articles, and exploratory analyses such as cluster analysis and relational indicators. We also consider the machine learning classification algorithm i.e. agglomerative hierarchical clustering for the categorization of clusters. The findings show that, for disruptive risks, collaborative sharing of labour and material resources are effective for the recovery of supply chains. More so, labour resources tend to contribute more to the recovery of supply chains. Whilst information resources and a mix of information and material resources are highly important in reducing the impact of COVID-19 disruptive supply chain risk. In conclusion, collaborating on the three resources, namely labour, material, and information resources can be an effective post-disruption recovery strategy for supply chains. </p
... The current understanding of risks and uncertainties within global supply chains stems from the area of supply chain risk and resilience research following 9/11 2001. Sheffi (2001) points out the effects of the World Trade Centre terrorist attacks on the global flow of goods. The effects may be indirect but was devastating, nevertheless. ...
... Since then, several authors have addressed the relationship between risk and supply chains (Robinson et al. 1967;Burnes and Dale 1998;Burnes and New 1996;Cousins et al. 2004;Hood and Young 2005;March and Shapira 1987;Johnson and Haug 2021;Alora and Barua 2022;Ekwall and Lantz 2021). Studies of supply chain risks seldom address specific causes of risk (Christopher and Lee 2004;Christopher and Peck 2004;Juttner 2005;and Sheffi 2001). They simply mention supply chain risk sources without discussing causes such as theft, smuggling, sabotage, and criminal activity. ...
Full-text available
This paper examines weekly and annual seasonality in incident categories to find patterns and trends in transport crime globally, concerning the value of stolen goods, incident frequency and incident category. Secondary data is utilized to analyse a contemporary challenge in logistics and supply chain research, namely theft and robbery of goods during shipment. The research is based on the TAPA global IIS transport-related crime database. Incident frequencies and mean values are analysed primarily with chi-square tests and analyses of variance (ANOVAs). The results are analysed and discussed within a frame of reference consisting of theories from logis- tics and criminology. The main conclusion is that there is an annual as well as a weekly seasonality of most incident categories, but the patterns vary among incident categories. The results are primarily limited by the content and classification within the TAPA IIS database.
... Instead, daily supply chain management questions, such as the poor quality of purchased products and services, are also pointed as important sources of instability, possibly presenting a domino effect from their origin to the final customer (Zsidisin, Panelli and Upton, 2000). In dealing with these matters, supply chains would become less efficient, as operational redundancies, less reliable lead times and less certain demand scenarios (Sheffi, 2001) would follow disruption management. Even leading manufacturing companies such as Dell, Toyota and Motorola, for instance, would incur in the maintenance of additional levels of inventory, capacity and other connected elements throughout their entire supply chains as manners to treat the issue (Chopra and Sodhi, 2004). ...
The association of firms to crimes, condemnable management practices, operational difficulties and / or fails carried out by their partners suggests that negative events occurred in a firm (i.e. source firm) hold the potential to negatively affect others. As firms’ direct and indirect relationships with their partners become less obvious, supply chain risks (March and Shapira, 1987) must be reconsidered to account for this contemporary and possibly hazardous prospect. In addressing this issue, the present dissertation investigates the impacts of negative corporate events to supply chain partners. Throughout three individual but interconnected articles, empirical evidence suggest that beyond the interruption of physical flows, unfavorable circumstances may not be restricted to firms originating them, spreading across their networks. More specifically, based on the premises of the Efficient Market Hypothesis (Fama, Fisher, Jensen and Roll, 1969; Fama, 1970; Jensen, 1978), the utilization of the event study method (Fama, 1970; Brown and Warner, 1980) allowed the demonstration of negative reactions from investors of supply chain partners upon the disclosure of adverse news. In referring to these outcomes, the concept of supply chain contamination is here defined as “the dissemination of negative events through supply chains, negatively affecting not only the market value of customers and suppliers (possibly that of customers of customers and suppliers of suppliers and so on), as well as potentially other dimensions such as corporate reputations, for instance” (Fracarolli Nunes, 2018: 581).Initial theorization of this process is also proposed. The mechanics leading a company to be affected by events originated out of its organizational borders is portrayed in the concept of the inertial effect, illustrated in the image of “the waves caused by a stone that hits the water previously rested” (Fracarolli Nunes and Lee Park, 2016: 292). Within the reasoning of unintended or unanticipated consequences (Merton, 1936), the occurrence of supply chain contamination through the inertial effect is considered a collateral effect. From the intersection of the literatures on supply chain management and the Stakeholder Theory, a new conceptual model is developed. Building on the idea that stakeholders stand for any individual, entity or group that shall either affect or be affected by the operations of a company (Freeman, 1984), the empirical demonstration that investors of a supply chain partner must be affected (i.e. collateral effect) by negative events occurred in or caused by a source firm (i.e. supply chain contamination through the inertial effect), allows the proposition of the concept of incidental stakeholders, here defined as “stakeholders of stakeholders, which, as such, may not be aware of their links with other companies, or even not consciously willing to take the risks associated with such a subsidiary connection” (Fracarolli Nunes, 2019: 4). In this sense, the investigation of 30 cases classified in 5 distinct categories (environmental disaster, corporate social and environmental irresponsibilities, operational failure, corporate fraud and corruption) is expected to offer new perspectives on the structural risks associated to supply chains. Along with the theoretical discussions, practical utilizations are approached, as well as avenues for future inquiries.
... These include human failures, financial bottlenecks, and internal accidents, such as fires or breakdowns in central production facilities. Conversely, external disruptions are caused by the environment surrounding the supply chain and can therefore be avoided or mitigated less easily, such as pandemics, natural disasters, economic setbacks, and deliberate threats including terrorist attacks (Park et al., 2013;Sheffi, 2001). ...
This tertiary study systematically analyzes 65 literature reviews on supply chain resilience (SCR) published in academic journals or conference proceedings. Our focus is on the vulnerabilities and capabilities of a supply chain that need to be balanced to achieve resilience. We explore the interdependencies of these two categories of SCR by developing an innovative framework to realize capabilities after identifying the SCR vulnerabilities. First, we propose a framework that systematizes the vulnerabilities and capabilities identified in the literature. Then, we discuss the identified SCR characteristics based on the framework and quantitatively evaluate the literature reviews’ focus on the two SCR categories. A synthesis of the research results shows the SCR characteristics addressed in the literature and reveals deficits for specific vulnerabilities. Finally, we outline future research opportunities based on these findings by mapping SCR capabilities and vulnerabilities in light of Industry 4.0 and digital supply chain developments. Then, we derive research gaps and recommended actions for practitioners in the context of SCR and Industry 4.0. Appendices/Supplementary materials are available on request by emailing the corresponding author or can be obtained under
... Banned from trading with US suppliers, Huawei had to replace US suppliers with China's and other countries' suppliers to reshape its supply chain rapidly [18]. Additionally, in 2001, the US government closed borders in response to large-scale terrorist acts, leading to the transportation disruptions of manufacturers operating the "Just-in-Time" (JIT) inventory discipline (e.g., Ford, Toyota, etc.) [8]. In complex network theory, a political conflict is represented as the removal of the connections between nodes or blocking the flow among nodes, resulting in cascading failures throughout the entire network. ...
Full-text available
Supply chain viability concerns the entire supply system rather than one company or one single chain to survive COVID-19 disruptions. Mobility restriction and overall demand decline lead to systematically cascading disruptions that are more severe and longer lasting than those caused by natural disasters and political conflicts. In the present study, the authors find that large companies and manufacturers with traditional advantages suffer greater losses than small ones, which is conceptualized as the "Hub Paradox" by empirically investigating one Warp Knitting Industrial Zone of China. An underload cascading failure model is employed to simulate supply chain viability under disruptions. Numerical simulations demonstrate that when the load decreases beyond a threshold, the viability will drop down critically. Besides, supply chain viability depends on two aspects: the adaptive capability of the manufacturers themselves and the adaptive capability of the connections of the supply network. The comparison study demonstrates that enhancing cooperative relations between hub and non-hub manufacturers will facilitate the entire supply network viability. The present study sheds light on viable supply chain management. Compared with conventionally linear or resilient supply chains, intertwined supply networks can leverage viability with higher adaptation of redistributing production capacities among manufacturers to re-establish overall scale advantages. Finally, the present study also suggests solving the "Hub Paradox" from the perspective of complex adaptive system. Supplementary information: The online version contains supplementary material available at 10.1007/s11071-022-07741-8.
... Expatriate staff underperform due to stress caused by the extra security measures, and construction workers are unwilling to work at night or on weekends (Tingbani et al. 2019). Thus, the supply chain is interrupted with consequences beyond the targeted businesses and industries (Sheffi 2001). Terrorism impacts not only the affected target but also local industries, foreign investments, geopolitical alliances, growth rate, global supply chains, tourism, consumer behaviours and productivity directly. ...
Full-text available
The economic development of many countries globally relies heavily on tourism arrivals and spending. Terrorist attacks, political unrest, and other external shocks create disruptions and imbalances that lead to tourism crises with devastating effects on a country’s economy. The paper quantitatively examines the wider economic impacts and welfare effects of a continued decrease in tourism revenues caused by terrorism and political instability on the Kenyan economy. We use a dynamic Computable General Equilibrium model which we calibrate to a 2003 Social Accounting Matrix for Kanya. Our results reveal that a decrease in tourism spending causes a contraction of the economy in the short-term and long-term. Tourism contraction leads to decreased output, prices and wages in urban households, whereas the rural households notice an increase in welfare in the short and medium-term and a decrease in the long-term. Diversification of the tourism product, better branding, crisis management preparations and emphasis on domestic tourism that is less affected by disruption are ways to safeguard tourism in Kenya and beyond.
In 2020 COVID -19 caused global disruptions in the supply chain that are still showing ripple effects in mid-2022. Pandemics are not the only form of crisis that causes supply chain disruptions. With increasing instances of natural disasters, organizational misconduct, economic instability, and political unrest, crisis management has become a growing issue within businesses and the supply chain field. This article examines the previous literature on crisis management by identifying the types of crises that will affect a focal firm’s suppliers in the chain, and how those types of crises will affect the supply chain. We continue by adding response measures through creating modular design and modular innovation capability, which will not prevent the crisis but will drastically decrease supply disruption and thus decrease response time for the focal firm. Lastly, a model is created for future empirical research based off of the previous literature that shows how modular design and modular innovation capability can alleviate the damage of crises in the supply chain through greater agility, flexibility, and adaptability.
Purpose The COVID-19 outbreak highlights that many supply chains are exposed to unforeseen disruptions, that risks are unavoidable, and that the international nature of supply chains can seriously disrupt normal operations. Therefore, the need for Supply Chain Resilience (SCRES) is more imperative than ever. Furthermore, collaboration in supply chains may have benefitted the response to the COVID-19 outbreak. The aim of this research is to gain a deeper understanding of how collaboration with both types of horizontal and vertical collaboration in the supply chain affects its resilience. Design/methodology/approach A thematic analysis of the literature is used to investigate the concepts of both vertical and horizontal collaboration and supply chain resilience separately, then integrating identified themes to understand the relationship between them through a thematic map. Findings The thematic analysis indicates that the more firms collaborate in the supply chain, the more resilient they will be. Furthermore, both horizontal and vertical collaboration between supply chain partners will enhance resilience. This relationship is positively moderated by governance in the partnership and negatively moderated by competition in the partnership. Originality/value This is one of the first papers to provide in-depth insights into how collaboration, with both types of horizontal and vertical collaboration, affects supply chain resilience. Neither of previous articles provide an understanding of how both types of collaboration enables supply chain resilience.
This paper studies the reliable uncapacitated facility location problem in which facilities are subject to uncertain disruptions. A two-stage distributionally robust model is formulated, which optimizes the facility location decisions so as to minimize the fixed facility location cost and the expected transportation cost of serving customers under the worst-case disruption distribution. The model is formulated in a general form, where the uncertain joint distribution of disruptions is partially characterized and is allowed to have any prespecified dependency structure. This model extends several related models in the literature, including the stochastic one with explicitly given disruption distribution and the robust one with moment information on disruptions. An efficient cutting plane algorithm is proposed to solve this model, where the separation problem is solved respectively by a polynomial-time algorithm in the stochastic case and by a column generation approach in the robust case. Extensive numerical study shows that the proposed cutting plane algorithm not only outperforms the best-known algorithm in the literature for the stochastic problem under independent disruptions but also efficiently solves the robust problem under correlated disruptions. The practical performance of the robust models is verified in a simulation based on historical typhoon data in China. The numerical results further indicate that the robust model with even a small amount of information on disruption correlation can mitigate the conservativeness and improve the location decision significantly. Summary of Contribution: In this paper, we study the reliable uncapacitated facility location problem under uncertain facility disruptions. The problem is formulated as a two-stage distributionally robust model, which generalizes several related models in the literature, including the stochastic one with explicitly given disruption distribution and the robust one with moment information on disruptions. To solve this generalized model, we propose a cutting plane algorithm, where the separation problem is solved respectively by a polynomial-time algorithm in the stochastic case and by a column generation approach in the robust case. The efficiency and effectiveness of the proposed algorithm are validated through extensive numerical experiments. We also conduct a data-driven simulation based on historical typhoon data in China to verify the practical performance of the proposed robust model. The numerical results further reveal insights into the value of information on disruption correlation in improving the robust location decisions.
Full-text available
Studies in the psychology of individual choice have identified numerous cognitive and other bounds on human rationality, often producing systematic errors and biases. Yet for the most part models of aggregate phenomena in management science and economics are not consistent with such micro-empirical knowledge of individual decision-making. One explanation has been the difficulty of extending the experimental methods used to study individual decisions to aggregate, dynamic settings. This paper reports an experiment on the generation of macrodynamics from microstructure in a common managerial context. Subjects manage a simulated inventory distribution system which contains multiple actors, feedbacks, nonlinearities, and time delays. The interaction of individual decisions with the structure of the simulated firm produces aggregate dynamics which systematically diverge from optimal behavior. An anchoring and adjustment heuristic for stock management is proposed as a model of the subjects' decision processes. Econometric tests show the rule explains the subjects' behavior well. The estimation results identify several `misperceptions of feedback' which account for the poor performance of the subjects. In particular, subjects are shown to be insensitive to the feedbacks from their decisions to the environment. Finally, the generality of the results is considered and implications for behavioral theories of aggregate social and economic dynamics are explored.
Full-text available
En la UE se ha estimado que los costes de la congesti�n representan el 2% de su PIB y que el coste de la poluci�n del aire y ruido supera el 0,6% del PIB, siendo alrededor del 90% de los mismos ocasionados por el transporte terrestre. Ante este hecho y el continuo aumento de la demanda del transporte privado frente al p�blico para los desplazamientos, muchos abogan por una conjunci�n de medidas tanto restrictivas como alternativas al uso del coche. Dentro de las primeras se encuentra el establecimiento de un peaje o una tarifa por el uso de las carreteras, medida que aunque desde el punto de vista de la Teor�a Econ�mica es la manera m�s eficiente para corregir el fallo de mercado que supone la congesti�n, desde la visi�n de pol�ticos y del p�blico no goza de gran aceptaci�n. En este trabajo se pretende hacer una simulaci�n de los efectos que tendr�a sobre el bienestar social de la implantaci�n de una medida de este tipo en la Bah�a de C�diz. In the European Union it has been estimated that the congestion cost are the 2% of the gross domestic product and the cost of pollution and noise is over 0,6%, olso it is known that the 90% of this cost are caused by overland transport. For this reason and for the always increasing demand of private transport, there are professionals who thinks that the solution have to be restrictive measures added to alternatives to the car. road pricing is a restrictive measures that for the economic theory is the most efficient way to solve congestion cost but for politicians and user of transport is not always accepted. In this study we are going to simulate road pricing for commuters in the Bah�a of C�diz and then it will be estimated welfare effects.
In recent years laboratory experiments have shed significant light on human behavior in a variety of microeconomic and decision-theoretic contexts including auctions, bargaining, and preference elicitation (Plott 1986, Smith 1986, Slovic and Lichtenstein 1983). Despite the success of experimental techniques in the domain of the individual and small group, there has been comparatively little work relating the behavior of decision makers to the dynamics of larger organizations such as an industry or the macroeconomy. Experiments in both economics and psychology have focussed (with significant exceptions, e.g. Hogarth and Makridakis 1981, Kleinmuntz 1985, Brehmer 1986, Smith 1986) on static and discrete judgments. Hogarth (1981, 198) emphasizes …the continuous, adaptive nature of the judgmental processes used to cope with a complex, changing environment…. With few exceptions…judgment researchers have focussed on discrete incidents (particular actions, predictions, and choices) that punctuate these continuous processes; furthermore, task environments are typically conceptualized to be stable.…. [I]nsufficient attention has been paid to the effect of feedback between organism and environment.