Andrew P. Tarko

Andrew P. Tarko
Purdue University | Purdue · School of Civil Engineering

PhD

About

160
Publications
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2,910
Citations

Publications

Publications (160)
Article
A driving strategy for autonomous vehicles (AVs) that is consistent with human behavior while demonstrating superior performance seems to have a good chance to be accepted by early AV users and be successful in the long run. Most of the past research focused on motion strategies affected by the presence of other vehicles. On the other hand, AV not...
Article
In recent years, the development and testing of autonomous driving technology have become widespread around the world. However, due to differences in perception abilities between autonomous vehicles and human drivers, the current geometric design controls for highway alignments, designed for the human driver, may not be applicable to the autonomous...
Article
After decades of research on traffic conflicts and other crash surrogate events, defining these events and conclusively connecting them with crashes continue to be the most important tasks. This paper aims to help establish a consensus on these two fundamental matters by discussing the underlying concepts by which they can be connected in a consist...
Article
Operating speed is often used to evaluate consistency in road geometric design. In the China, the Specifications for Highway Safety Audit includes a spot-based speed model that predicts operating speed by dividing the road into homogeneous segments and observing the speeds at sparsely spaced spots. This paper presents a continuous speed model as a...
Article
Unobserved heterogeneity has been a major challenge in developing reliable road safety models. A number of statistical techniques have been developed to account for unobserved heterogeneity and of which, the random parameters approach is one of the most effective method and has been frequently used recently. In this study, to ascertain the performa...
Article
Although the frequency and severity of crashes are direct measures of road safety, crash data are typically of limited quality and they require long data collection periods to produce conclusive results. Surrogates of crashes that would allow a quick and accurate estimation of safety have been an active topic for years. Among multiple alternatives,...
Article
Traffic signals are installed at road intersections to improve their capacity and safety. Separating traffic flows in time reduces right-angle collisions but may increase rear-end collisions. Properly designed change periods and yellow signals, sufficiently long turning bays, and good progression of coordinated signals improve safety by reducing st...
Article
Operating speed profiles represent drivers’ responses to roadway geometry and are widely used to evaluate safety performance of roadway design. To predict operating speed profile, the majority of early research followed a two-step modeling procedure: (1) estimate speeds at start, middle, and end points of road segments, and (2) fill the profile bet...
Article
Surrogate measures of safety attract revived interest thanks to the advancements in traffic observations techniques and the growing need for rapid safety evaluation. A new method of safety analysis based on failure-caused traffic conflicts and the Lomax distribution was recently proposed to estimate crash frequency more efficiently than with crash...
Article
Count models, such as negative binomial regression, are well-established statistical methods for analyzing road safety. Although count models are widely used for arterial roads, their application to rural local roads is sparse, partly due to the concern of possible estimation bias caused by low crash counts. This paper revisits the matter to furthe...
Technical Report
After repeal of the National Maximum Speed Limit Law, states were allowed to set individual speed limits on their interstate roads. Several states opted for a uniform speed limit while others implemented differential speed limits. The current speed limit on Indiana rural freeways limits speed of passenger cars to 70 mph and restricts to 65 mph spee...
Preprint
Full-text available
Five car-following models were calibrated, validated and cross-compared. The intelligent driver model performed best among the evaluated models. Considerable behavioral differences between different drivers were found. Calibrated model parameters may not be numerically equivalent with observed ones.
Article
Queue spillback onto the freeway mainlines and the interactions with the adjacent intersections can have adverse impacts on traffic operation and safety, whereby the freeway becomes an expensive substitute for storing vehicles when spillback is prevalent. Thus, queue spillback onto the freeway mainlines and adjacent intersections should be analyzed...
Article
In response to the rapid economic growth in China, its freeway system has become the longest in the world and likely will continue to expand. Unfortunately, the safety issues on freeways in China have grown as well and are of great concern to Chinese transportation authorities and drivers. While many proven safety countermeasures developed and impl...
Chapter
Purpose – This chapter overviews surrogate measures of safety to help better understand the related challenges and opportunities. The chapter is meant to serve as a primer for practitioners looking for alternative methods of evaluating safety where crashes are lacking or are insufficient. Approach – The historical perspective and the current state-...
Article
This paper justifies the Lomax distribution for counterfactual modeling of the probability of crash given a traffic conflict. The pre-crash process leading to a conflict or a crash as the result of a failure is discussed as this conceptualization is the basis for proposing a simple model of the probability of a crash at the moment when a conflict i...
Article
The majority of past road safety studies focused on open road segments while only a few focused on tunnels. Moreover, the past tunnel studies produced some inconsistent results about the safety effects of the traffic patterns, the tunnel design, and the pavement conditions. The effects of these conditions therefore remain unknown, especially for fr...
Article
The objective of this study was to develop crash modification factors (CMFs) and estimate the average crash costs applicable to a wide range of road-barrier scenarios that involved three types of road barriers (concrete barriers, W-beam guardrails, and high-tension cable barriers) to produce a suitable basis for comparing barrier-oriented design al...
Article
Unlike most of traffic safety treatments that prevent crashes, road barriers reduce the severity of crash outcomes by replacing crashes with a high risk of severe injury and fatality (such as median crossover head-on collisions or collisions with high-hazard objects) with less risky events (such as collisions with barriers). This “crash conversion”...
Technical Report
Full-text available
The ability to accurately measure and cost-effectively collect traffic data at road intersections is needed to improve their safety and operations. This study investigates the feasibility of using laser ranging technology (LiDAR) for this purpose. The proposed technology does not experience some of the problems of the current video-based technology...
Article
The rollover propensity of SUVs and trucks has long been recognized as a potential safety issue. The propensity may increase with the growing number of roundabouts that are being built on high-speed roadways designed for 50 mi/h or higher. This paper presents a research methodology developed to evaluate the rollover propensity of trucks on existing...
Article
In Indiana, roundabout construction recently commenced on high-speed roadways (i.e., with posted speed limits of 50 mph or higher), many carrying significant truck traffic. Studies show that heavy vehicle rollovers may be an issue at roundabouts. A case study compared the safety-related behavior of truck drivers at roundabouts on low- and high-spee...
Conference Paper
The presented study aimed to determine how much the recent trend in motorcycle safety was influenced by weather on the example of Indiana. To confirm this hypothesis, a statistical crash counts model was developed to connect the weather with the monthly and annual number of motorcycle crashes and to estimate the hypothetical trend under the assumpt...
Article
This article proposes a new method for fitting the horizontal alignment of a road to a set of (x, y) points. Those points can be obtained from digital imagery or GPS-data collection. Unlike current methods that represent road alignment through its curvature, the proposed method describes the horizontal alignment as a sequence of headings. An analyt...
Article
Combined horizontal and vertical alignments are frequently used in mountainous freeways in China; however, design guidelines that consider the safety impact of combined alignments are not currently available. Past field studies have provided some data on the relationship between road alignment and safety, but the effects of differing combined align...
Article
Full-text available
Transportation agencies require up-to-date, reliable, and feasibly acquired information on road geometry and features within proximity to the roads as input for evaluating and prioritizing new or improvement road projects. The information needed for a robust evaluation of road projects includes road centerline, width, and extent together with the a...
Article
Roadway departure crashes tend to be severe, especially when the roadside exposes the occupants of errant vehicles to excessive injury hazards. As a cost-effective method when the clear zone width is insufficient, road barriers are often installed to prevent errant vehicles from colliding with dangerous obstacles or traversing steep slopes. This pa...
Article
Full-text available
Because the quality of decision making in road safety is dependent on the quality of the data on which decisions are based, efforts to improve the quality, timeliness, and accuracy of crash databases are crucial. A critical review of Australasian, European Union, and U.S. crash databases was performed, and future directions were identified. Major i...
Article
The study of road safety has seen great strides over the past few decades with advances in analytical methods and research tools that allow researchers to provide insights into the complex interactions of the driver, vehicle, and roadway. Data collection methods range from traditional traffic and roadway sensors to instrumented vehicles and driving...
Article
Real-time crash risk prediction using traffic data collected from loop detector stations is useful in dynamic safety management systems aimed at improving traffic safety through application of proactive safety countermeasures. The major drawback of most of the existing studies is that they focus on the crash risk without consideration of crash seve...
Article
This paper presents an investigation of traffic safety in highway work zones using detailed data obtained from the results of a survey of project engineers and existing datasets. The observations were organized in monthly clusters that correspond to individual work zones; and a two-level random parameters negative binomial model that reflected the...
Article
The goal of safety management is to reduce the number and severity of crashes in transportation networks. One of the methods of safety management is identification of roads that experience an excessive number of crashes by comparison of the actual number of crashes with exposure-based predictions. The identification task typically includes division...
Article
Highway work zone safety has been a concern nationwide and will likely draw ever increasing attention as more highway funds are invested in the maintenance of existing highways. To improve work zone safety, the Indiana Department of Transportation (DOT) established a special fund for work zone patrolling, and this study was commissioned to help the...
Article
Full-text available
Crash data collection is crucial for road safety improvement, but Italy is considerably behind the best international practices. To help to bridge this gap, a critical review of international crash databases was carried out and recommendations for improvement of the Italian police crash data collection and the national crash database were formulate...
Article
The limited ability of existing safety models to properly reflect crash causality has its source in cross-sectional analysis applied to the estimation of the intrinsically complex safety factors with highly aggregated and frequently poor quality of data. The adequacy of the data may be improved thanks to the unprecedented progress in sensing techno...
Article
The Indiana Department of Transportation (INDOT) manages road safety in Indiana through safety emphasis areas, identification of safety needs within these areas, and development and implementation of transportation interventions that address the safety needs. Indiana applies system-wide performance screening to state roads using the somewhat limite...
Article
Since 2006, INDOT has been preparing an annual five-percent report that identifies intersections and segments on Indiana state roads that require attention due to the excessive number and severity of crashes. Many of the identified intersections are two-way, stop-controlled intersections located on high-speed, multi-lane, rural roads. Some contribu...
Article
Traffic signals are coordinated to improve traffic mobility, but the impact of coordination, particularly specific coordination solutions, on safety is not well known. Engineers who set coordinated signals can use several tools to improve traffic mobility but have no tool with which to account for safety. A study was done on the impact of arterial...
Article
Evaluation of crash-related injuries by medical specialists in hospitals is believed to be more exact than rather a cursory evaluation made at the crash scene. Safety analysts sometimes reach for hospital data and use them in combination with the police crash data. One issue that needs to be addressed is the, so-called, selectivity (or selection) b...
Article
Full-text available
The presented research used a driving simulator to study the effect of isolated vertical crest curves overlapped with horizontal curves on driver's perception and behavior. The curves were consistent with the existing design standards. The research was conducted in four phases: (1) Design a test road with road design software; (2) Convert the desig...
Article
Full-text available
Super 70 was an urban reconstruction project (March-November 2007) along I-70 in the central part of Indianapolis. INDOT applied in that project several innovative and traditional solutions. This study investigates the safety effect of the solutions. Advanced econometric models were applied to study both the spatial differences in the risk of crash...
Article
The evaluation of crash severities and the estimation of crash costs are key elements in evidence-based traffic safety improvement programs. Police records include information on injury severity estimated at the scene either by a police officer or by a medical emergency unit. At a hospital, the accident injuries are examined and documented more tho...
Article
High-tensioned cable barriers have been introduced in the United States as a median barrier option, primarily as a result of state agencies looking for a cost-effective means by which to mitigate or eliminate cross-median crashes. This paper studies the impact of cable barriers on crash frequency and severity in a way that can be utilized in the be...
Article
Road intersections and segments identify and as experiencing high number of crashes are investigated to identify roadway and traffic control deficiencies and relevant safety countermeasures. Site investigators must rely on their experience and judgment which may be an overwhelming task to those who lack such an experience. This paper presents a con...
Article
The limited quality of location data poses a major problem to those who want to use such data for research or safety management. The proportion of crashes unassigned to specific road locations is considerable. This fact is sometimes overlooked because crash database queries return crashes assignable to locations but do not issue warnings about cras...
Article
The first and most important step in road safety management is the identification of roads with safety needs. One possible road screening technique is based on the quality control method. Exposure data such as annual average daily traffic and vehicle miles traveled are used to estimate the expected numbers of crashes, which are then compared with t...
Conference Paper
Full-text available
Although driving simulators replicate the real driving conditions, the driving risk is eliminated and most driving conditions are controlled. The presented research used a driving simulator to study the effect of isolated vertical crest curves overlapped with horizontal curves on driver perception and behavior. The curves were consistent with the e...
Article
This paper proposes a new model of driver-preferred speeds derived from the assumption that drivers trade-off a portion of their safety for a time gain. The risk of receiving a ticket for speeding is also considered. A trip disutility concept is selected to combine the three components of speed choice (safety, time, and enforcement). The perceived...
Article
In this paper, two-state Markov switching models are proposed to study accident frequencies. These models assume that there are two unobserved states of roadway safety, and that roadway entities (roadway segments) can switch between these states over time. The states are distinct, in the sense that in the different states accident frequencies are g...
Article
Although median barriers are an absolute means of preventing drivers from crossing road medians and colliding with vehicles moving in the opposite direction, they may cause additional crashes. This perhaps complex safety effect of median barriers has not been investigated well. Being able to predict the safety impact of most types of median barrier...
Article
The growing use of packages based on geographic information systems (GISs) in transportation planning is assisting in the development and implementation of methods that facilitate consideration of safety. This paper presents a method of predicting safety for planning alternatives. Although applicable to large road networks, the method predicts cras...
Article
There has been an abundance of research that has used Poisson models and its variants (negative binomial and zero-inflated models) to improve our understanding of the factors that affect accident frequencies on roadway segments. This study explores the application of an alternate method, tobit regression, by viewing vehicle accident rates directly...
Article
In some situations, the horizontal alignment of a road, particularly circular curves, are designed for reduced speeds compared to their adjacent sections to reduce costs and to avoid compromising the qualities of historical districts and areas of special value. Thus far, there is no sufficient research on driver behavior in the vicinity of curves w...
Article
Full-text available
This manual is an instructional and support material for PASS (Planning Analysis Software for Safety) and INPASS (INput to Planning Analysis Software for Safety) tools. This manual includes detailed information on how the PASS and INPASS tools work, what features are available, what the required input format is and what output is generated by the t...
Article
Crash-based safety analysis is hampered by several shortcomings, such as randomness and rarity of crash occurrences, lack of timeliness, and inconsistency in crash reporting. Safety analysis based on observable traffic characteristics more frequent than crashes is one promising alternative. In this research, we proposed a novel application of the e...
Article
Full-text available
Submitted for presentation at the 85 th Annual Meeting of the Transportation Research Board, January 22-26, 2006, Washington DC Number of words in manuscript = 5736 Tables and figures = 7 x 250 = 1750 Total number of words = 7486 TRB 2006 Annual Meeting CD-ROM Paper revised from original submittal. 1 ABSTRACT Misinterpretation of the risk by driver...
Article
Full-text available
The current planning practice addresses safety implicitly as a byproduct of adding capacity and operational efficiency to the transportation system. Safety conscious planning is a new proactive approach to the prevention of crashes by establishing inherently safe transportation networks through integrating safety consideration into the transportati...
Article
Full-text available
Statistics indicate that accidents at signalized intersections have become a significant safety problem throughout the United States. Right-angle collision is ranked the highest in terms of severity at signalized intersections while its frequency is only second to rear-end collisions. One key component that is lacking is a tool to help identify exc...
Article
Full-text available
This paper presents research on driver risk perception and its connection with driver selection of speed and with highway safety. The paper supports the theory of rational behavior. The implications of driver risk perception on the speed-safety relationship and on using speed as a surrogate measure of safety are discussed. We distinguish two distin...
Article
Full-text available
This paper proposes a new probabilistic method of protecting drivers against Type-I dilemmas that may occur upon the display of a yellow traffic signal. At the onset of yellow, an approaching vehicle may be too close to stop but also too far away to pass the stop line before the end of yellow. The occurrence of this dilemma situation is affected by...
Article
Full-text available
Travel speed is a key measure of effectiveness in evaluating urban arterials. The Highway Capacity Manual (HCM) methodology of predicting speeds along urban streets requires complex calculations and input not typically available in long-range planning. The use of default values is therefore necessary. This paper demonstrates that a simple and pract...
Article
Full-text available
This paper presents research on driver risk perception and its connection with driver selection of speed and with highway safety. The paper also supports the theory of rational behavior. The implications of driver risk perception on the speed–safety relationship and on use of speed as a surrogate measure of safety are discussed. The authors disting...
Article
The current planning practice addresses safety implicitly as a by-product of adding capacity and operational efficiency to the transportation system. Safety-conscious planning is a new proactive approach to the prevention of crashes based on establishing inherently safe transportation networks through integrating consideration of safety into the tr...
Article
Statistics indicate that accidents at signalized intersections have become a significant safety problem throughout the United States. Right-angle collisions are ranked highest in terms of severity at signalized intersections, while their frequency is second only to rear-end collisions. One key component that is lacking is a tool to help identify ex...
Article
Travel speed is a key measure of effectiveness in evaluating urban arterials. The Highway Capacity Manual (HCM) methodology of predicting speeds along urban streets requires complex calculations and input not typically available in long-range planning. The use of default values is therefore necessary. This paper demonstrates that a simple and pract...
Article
This paper proposes a new probabilistic method of protecting drivers against Type I dilemmas that may occur on the display of a yellow traffic signal. At the onset of yellow, an approaching vehicle may be too close to stop but also too far away to pass the stop line before the end of yellow. The occurrence of this dilemma is affected by factors suc...
Article
Full-text available
Past research has indicated that the accuracy of traffic quality studies strongly depends on capacity parameters, particularly when demand approaches capacity. Minimal work has been done in the past on local values of the base saturation flow rate and lost times used in capacity analysis of signalized intersections. This paper discusses saturation...
Article
Full-text available
The mean free-flow speed and its variability across drivers are considered important safety factors. Despite a large body of research on operating speeds, there is still much to learn about the factors of free-flow speeds, especially on tangent segments of two-lane rural highways. The roadway factors of speed dispersion across drivers are largely u...
Article
Full-text available
Submitted for presentation at the 84 th Annual Meeting of the Transportation Research Board, January 9-13, 2005, Washington D.C. Number of words in manuscript = 5128 Tables and figures = 7 x 250 = 1750 Total number of words = 6878 TRB 2005 Annual Meeting CD-ROM Paper revised from original submittal.
Article
Full-text available
Recent applications of modern technologies to transportation have increased the need for rapid evaluation of safety; and at the same time, they have presented new possibilities to measure safety. This paper discusses an extreme value theory approach to safety estimation using observable traffic characteristics. Unlike the past research on surrogate...