Modeling and Implementation of Bus Rapid Transit corridor based on Traffic Prioritization and Automatic Location

Full text

International Conference on Applied Internet and Information
Technologies, 2016
DOI:10.20544/AIIT2016.38
Modeling and Implementation of Bus Rapid Transit
corridor based on Traffic Prioritization and Automatic
Location
Ioannis Patias, and Vasil Georgiev
Faculty of Mathematics and Informatics
University of Sofia St.Kliment Ohridski“
5 James Bourchier blvd., 1164, Sofia, Bulgaria
ioannis.patias@gmail.com
Abstract. In many cities facts defining conditions for very high concentration of
functions and population make transport difficult. The proposed solution is an
Automated Vehicle Location (AVL) and prioritization system for mass urban
transport buses, and priority vehicles, through a Bus Rapid Transit (BRT) corridor.
The solution consists of a detection sub-system, with a bus component, using
transmitter, and a receiver placed on the traffic lights, the traffic lights, and a control
center. We aim in minimizing the waiting time on traffic lights, and thus the waste
of time on traveling. Such system is a useful instrument for any mass urban
transport system.
Keywords: Intelligent Transport System (ITS), Automated Vehicle Location
(AVL), Traffic Prioritization, Bus Rapid Transit (BRT).
1. Introduction
The term Intelligent Transport Systems (ITS) refers to a wide range of applications. The
most basic ones include simple traffic signal control and management systems, automatic
number plate recognition with speed cameras, security CCTV systems. The more
advanced applications can integrate real-time traffic and vehicle data and can regulate the
traffic in real-time with using such historical data.
Although ITS may refer to all modes of transport, EU Directive 2010/40/EU [1] (7 July
2010) defines ITS as systems in which information and communication technologies are
applied in the field of road transport, including infrastructure, vehicles and users, and in
traffic management and mobility management, as well as for interfaces with other modes
of transport. ITSs are important in increasing safety and also manage Europe's growing
emission and congestion problems. They make transport safer, more efficient and more
sustainable.
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On the other side in other countries, like the United States, the increased interest in the
area of ITSs is rather motivated by an increasing focus on homeland security. Many of
the proposed ITS systems also involve surveillance of the roadways, which is a priority
of homeland security [2, 3].
When talking about ITS, there is e a wide range of technologies applied [4]. Those
technologies include: data processing, management and archiving, detection,
communication, information dissemination, location referencing and positioning, traffic
control and vehicle control, electronic payment, and surveillance and enforcement
technologies.
Bus Prioritization System (BPS) or Transit Signal Priority (TSP) is an ITS aiming to
reduce the time waist on traffic lights for Mass Urban Public Transport vehicles. Although
are most often related with buses, they also are applied in trams, rails, etc., and any kind
of priority vehicles. In terms of technologies BPS involve traffic control, and detection
technologies.
There are two categories of BPS. The so-called active BPS is a system based on detecting
Mass Urban Public Transport vehicles as they approach the traffic light and adjusting the
traffic light’s timing dynamically, and thus create “green wave”, meaning uninterrupted
traffic along the bus line route. It is important to mention here that implemented this way
the system can also be used for the emergency vehicles, so from now on when we are
talking about buses we always mean also emergency vehicles. The most advanced active
BPS are based on AVL, and real-time Estimated Time of Arrival (ETA) calculation.
Passive BPS called those systems, which are built with specialized hardware and try to
optimize the traffic lights timing by using historical data, and this effect applies to all
vehicles along a route.
2. Literature Review
The term Ubiquitous Computing [5] is used to express the idea of a post-desktop model
of human-computer interaction, where we have integration of information processing into
everyday objects and activities. In many cases the end-user uses more than one distributed
systems and devices even simultaneously, without even being aware of their existence.
The implementation of this concept is not that easy. But the overall dividend is great. Our
life would be quite easier if all objects in the world surrounding us get equipped with
identifying devices.
The most widely used identifying devices are the ones using Radio-Frequency
Identification (RFID). RFID tags, or electronic labels are used with objects to be
monitored or tracked. The technology can be applied to any object, animal, or people. We
can identify and track the objects by using radio waves or sensing signals. There are tags,
which can be tracked with range of tens or hundreds of meters. The syntax of RFID tags
contains two major parts at least. The first is storing and processing information integrated
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Modeling and Implementation of Bus Rapid Transit corridor based on Traffic Prioritization and
Automatic Location
circuit, which is also modulating and demodulating a radio-frequency (RF) signal. The
second part consists of an antenna, used for receiving and transmitting the radio signals.
There are active, semi-active, and passive RFID tags. Tags can store up data and consist
of microchip, and antenna, and also battery for the cases of active and semi-passive tags.
All the components can be enclosed in plastic, or silicon. In general RFID tags help us in
our everyday activities, since they are not expensive, and at the same time they can apply
in almost any object.
The use of RFID enriches the options of systems used for giving priority to vehicles. The
concrete needs determine the most appropriate measures to be used. A feasibility study
should be implemented prior to the concrete measures to be used can be defined.
There are various ways of giving priority to buses, which could be broadly categorized as
[6]:
•physical measures,
•traffic signal priorities, and
•integrated measures.
Physical measures can include with and contra-flow lanes, bus only lanes or even streets.
Traffic signal priorities method’s typical example is the BPS. Integrated measures are
those, which combine traffic signal measures with physical measures. The latest is
applicable in cases where none of the first two systems alone is effective.
Focusing on the traffic signal priorities method, there are different systems
implementations. Those differentiations usually called traffic signal control systems and
strategies, and are categorized in:
•Isolated systems
In isolated systems the controlled by signal traffic light is located and operates
independently, this is why the term isolated traffic light is used. Traffic light’s signals can
also be linked to a Control Centre, but only for fault monitoring purposes, not for
management. Isolated system can further be divided into fixed time or vehicle actuated
(VA).
•Co-ordinated systems
Co-ordinated systems, are so called because they co-ordinate the operations at a traffic
light, with the operations at one or more neighboring traffic lights. All traffic lights have
to be connected to a centralized system implementing a Control Center system. Co-
ordinated under Control Center systems can be further divided into traffic responsive or
fixed time.
VA systems rely on detectors placed on traffic lights. When a bus approaches to the traffic
light, and once it is detected the traffic light performs the appropriate timing. A bus
approaching a traffic light with red light sends to the controller a demand for a green light.
The demand is then served by the controller, which can apply different timing cycles.
After serving any signals and with no more incoming ones, the controller will continue
the preprogrammed mode/s.
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The VA system can give priority both to buses, and any other special purpose and/or
emergency vehicle. Also the VA systems can serve different priority levels requests. This
means that special purpose vehicles can transmit a higher priority level “priority request”,
and thus be served with privilege.
3. System architecture
The proposed AVL and prioritization system for urban transport buses, through the BRT
corridor system architecture consists of the two major sub-systems, the vehicle, and the
traffic lights sub-system. The deployment diagrams of the two sub-systems are given in
the following figures:
Figure 1: Vehicle sub-system deployment diagram
Figure 2: Traffic lights sub-system deployment diagram
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Modeling and Implementation of Bus Rapid Transit corridor based on Traffic Prioritization and
Automatic Location
4. System functionality
At each junction the phase selector is set and configured according to respective approach
points for that intersection. Meaning when the bus approaches the intersection (and
assuming that a request for priority is activated by the onboard AVL system), the
intersection tracks the progress of the vehicle. When the bus reaches the predefined
distance to the intersection or the respective ETA time limit, the request is activated.
The respective priority signals are transmitted further, and the AVL system will activate
the application to ensuring priority. The request for priority is processed only if it is made
within the "virtual sensor" – a so-called area, the boundaries of which are determined by
the sensors positioning, defining the location of the intersection and the approaches to
them. Such geo-fencing may be of any shape or combination of shapes (e.g., square,
rectangle, a series of rectangles, etc.).
Using such software setup and phase selector configuration, the system makes the
approach zones corresponding to an intersection. Thus, suitable zones act based on
sensors, and they are used by the system to trigger a request for priority. And finally the
system allows the use of conditions, when requesting priority based on distance and / or
time.
When the bus is moving towards an intersection and the request for priority by AVL, its
location and ETA are calculated once per second. This additional functionality of using
the ETA as a variable for the operation, allows the system to take into consideration any
variations in the speed of the bus and to provide an effective extension of the green phase
or early termination of the red phase.
When the bus reaches a certain point approaching the intersection, static trigger point is
an optimal solution only if the buses are approaching the intersection with predefined
unchanging speed. Busses, that are faster than the average buses will need to point the
trigger further back from the intersection to ensure that the green phase is available and
the priority request has been overlooked. But, busses slower than the average bus will
have to trigger a request at a point closer to the intersection to avoid the use of more than
the optimum amount of the green phase and its extension. Thus, the system allows the
use of either pure distance from the intersection or a combination of distance/ETA of the
priority activation. Reaching that either a certain place or at some point a priority request
will be triggered. As a point of activation it can be set to a certain distance or a certain
period of time - whichever comes first. Meaning it is possible to make a combination of
the two activation criteria.
Converting the requests for priority in to data to the controller:
The phase selector, which is located at the intersections, is associated with the controller
supporting digital inputs with discrete signal wires. When a request for priority
intersection is approved, a request is transferred by any of the outputs of the phase selector
to the controller, by activating one of the electrical input controllers, each of which
corresponds to the direction of priority. This system allows the user to activate different
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traffic phases like straight, left, or right, depending on the current need. The signal to the
controller can be a constant low voltage to activate the highest priority, or pulsatile low
voltage to activate the low priority depending on the desired system performance. The
controller will recognize this signal as a priority for the phase and adjust the timing of
signals as programmed.
Assuring priority:
Each controller must be configured to provide priority, as follows:
Option 1. Prolongation of priority: Upon receiving the request for priority (through an
external input) and the priority phase/stage is a green signal in the direction of the bus,
then the green signal is extended to the set maximum time for priority (in addition to the
normal green time).
Option 2. Change Priority: Upon receiving the request for priority and priority
phase/stage is red, then the current phase is terminated prematurely but not suddenly with
the minimum values as assured safety limits and the following phases, which are also
reduced to the minimum required in order to proceed to the next cycle to reach the next
green phase/stage where the green signal will be extended in the direction of the bus.
Upon receiving of a request for priority during the yellow signal and when the next phase
is green, it will be the first option that will be used to proceed. And upon receiving of a
request for priority during the yellow signal and the next phase is red, then it will be the
second option that will be used to proceed.
5. Conclusions
The Automated Vehicle Location (AVL) and prioritization system for mass urban
transport buses, and priority vehicles, through the Bus Rapid Transit (BRT) corridor can
help both passengers and the mass urban transport authorities. Implemented in accordance
with the applied standards, it can minimize the waiting time on traffic lights, and thus the
waste of time on traveling, increasing this way the capacity of urban transport systems.
By increasing the passengers’ satisfaction, the number of passengers increases on public
transport together with the market share of public transport.
References
[1] DIRECTIVE 2010/40/EU OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:207:0001:0013:EN:PDF
[2] Torin Monahan, “WAR ROOMS” OF THE STREET: SURVEILLANCE PRACTICES IN
TRANSPORTATION CONTROL CENTERS, http://publicsurveillance.com/papers/
war_rooms.pdf, The Communication Review, 10: 367–389, 2007
[3] United States Department of Transportation, Intelligent Transportation System Strategic Plan
2015-2019. (http://www.its.dot.gov/landing/ strategicplan2015.htm)
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Automatic Location
[4] ROAD NETWORK OPERATIONS & INTELLIGENT TRANSPORT SYSTEMS http://rno-
its.piarc.org/en
[5] Kai Hwang, Geoffrey C. Fox, and Jack J. Dongarra, “Distributed and Cloud Computing From
Parallel Processing to the Internet of Things”, 2012 Elsevier.
[6] UK Department for Transport, Keeping Buses Moving. A Guide to Traffic Management to
Assist Buses in Urban Areas. (https://www.gov.uk/government/uploads/system/uploads/
attachment_data/file/329973/ltn-1-97__Keeping-buses-moving.pdf).
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