bluuebunny/crossref_metadata_2025 huggingface dataset:
Road Pricing with Autonomous Links
Authors: Zhang Lei , Levinson David
Published: May 2018

This research seeks to examine road pricing on a network of autonomous highway links. “Autonomous” refers to the links’ being competitive and independent and having the objective of maximizing their own profits without regard for either social welfare or the profits of other links. The principal goal of this research is to understand the implications of the adoption of road pricing and privatization on social welfare and the distribution of gains and losses. The specific pricing strategies of autonomous links are evaluated first under the condition of competition for simple networks. An agent-based modeling system is then developed; it integrates an equilibrated travel demand, route choice, and travel time model with a repeated game of autonomous links setting prices to maximize profit. The levels of profit, welfare consequences, and potential cooperative arrangements undertaken by autonomous links are evaluated. By studying how such an economic system may behave under various circumstances, the effectiveness of road pricing and road privatization as public policy can be assessed.
Bridge Inspection Quality Management
Authors: Dietrich Jaakko I. , Inkala Mikko A. , Männistö Vesa J.
Published: May 2018

Reliable data on the condition of bridge networks are critical for successful bridge management. However, little attention has been paid to the quality of the data gathered in bridge inspections. This paper reviews the most important areas of bridge inspection that cause variation in bridge condition data and presents possible misjudgments made as a result of poor inspection data quality. The main elements of the inspection quality management system adopted in the Finnish Road Administration are presented, and the development of the quality of inspection data in 2002 and 2003 is briefly summarized. The evidence shows that the quality of inspection data has improved considerably but that the current quality level is not yet sufficient. The quality control system could be improved by increasing inspector interaction during control inspections, using an independent consultant in inspection quality measurements and inspector training, increasing the number of quality measurements, and introducing quality targets.
Modification of Bending Beam Rheometer Specimen for Low-Temperature Evaluation of Bituminous Crack Sealants
Authors: Al-Qadi Imad L. , Loulizi Amara , Aref Susanne , Masson J.-F. , McGhee Kevin M.
Published: May 2018

It is difficult to evaluate effectively the low-temperature stiffness of bituminous hot-poured crack sealants with existing test methods. The standard bending beam rheometer (BBR) was found to be inappropriate for testing soft bituminous-based hot-poured crack sealant, even at a temperature of-40°C. To address this issue, the moment of inertia of the tested beam was increased by doubling its thickness (from 6.35 mm to 12.7 mm). For the new beam dimensions, only 4% of the beam center deflection is due to shear, a value deemed acceptable for sealant evaluation and comparison. On this basis, the BBR stiffness of hot-poured sealants was obtained at several discrete temperatures between-10°C and -40°C to assess the repeatability of the method for the evaluation of the low-temperature stiffness of bituminous sealants. Ten different sealants were tested at -40°C; three of these 10 were further tested at –35°C, –30°C, –28°C, –25°C, and –20°C; and the three “hard” sealants were tested at –10°C. A minimum of three replicates were used. The coefficient of variation on the measured stiffness after 60 s of loading was always lower than 18%, with almost 75% of the measurements having a coefficient of variation less than 10%. A pairwise comparison showed that the modified BBR could be used to classify sealant products according to their measured stiffness. As to the effect of temperature, it was found that the stiffness varies exponentially with temperature in the range of –40°C to –20°C. A statistical analysis of the results indicated that the modified BBR method could be used to classify sealants based on low-temperature stiffness.
Car-Following Behavior Analysis from Microscopic Trajectory Data
Authors: Ossen Saskia , Hoogendoorn Serge P.
Published: May 2018

The development of accurate and robust models in the field of car following has suffered greatly from the lack of appropriate microscopic data. Because of this lack, little is known about differences in car-following behavior between individual driver–vehicle combinations. This paper studies the car-following behaviors of individual drivers by making use of vehicle trajectory data extracted from high-resolution digital images collected at a high frequency from a helicopter. The analysis was performed by estimating the parameters of different specifications of the well-known Gazis–Herman–Rothery car-following rule for individual drivers. This analysis showed that a relation between the stimuli and the response could be established in 80% of the cases. The main contribution of this paper is that considerable differences between the car-following behaviors of individual drivers could be identified. These differences are expressed as different optimal parameter values for the reaction time and the sensitivity, as well as different car-following models that appear to be optimal on the basis of the data for individual drivers.
Modeling Speed Disturbance Absorption following Current State–Control Action–Expected State Chains
Authors: Tao Ruihua , Wei Heng , Wang Yinhai , Sisiopiku Virginia P.
Published: May 2018

This paper explores driver behavior in a paired car-following mode in response to a speed disturbance from a front vehicle. A current state– control action–expected state (SAS) chain is developed to provide a framework for modeling of the hierarchy of expected actions incurred during the need for speed disturbance absorption. Three car-following scenarios and one lane-changing scenario are identified with defined perceptual informative variables to describe the process of speed disturbance absorption. Those variables include dynamic spacing versus the follower's speed, disturbance-effecting and -ending spacing, headway, acceleration– deceleration, speed recovery period, speed advantage, and lane-changing duration. A significant improvement in car-following modeling introduced in the paper is the integration of car-following and lane-changing behaviors in the SAS chain. Moreover, critical values of perceptual informative variables are statistically developed as a function of the follower's speed by using observed vehicle trajectory data. Furthermore, models that determine the probability of a lane change in response to a speed disturbance and models for acceptable lane-changing decision-making conditions at the adjacent lanes are developed on the basis of the analysis of observed vehicle trajectory data. The work presented in this paper provides an analysis of speed disturbance and speed absorption phenomena and car-following and lane-changing behaviors at the microscopic level. This work establishes the foundation for further research on multiple speed disturbance absorption and its impact on traffic stabilities at the macroscopic analysis level.
Empirical Analysis of Traffic Sensor Data Surrounding a Bottleneck on a German Autobahn
Authors: Bertini Robert L. , Hansen Steven , Bogenberger Klaus
Published: May 2018

The evolution of traffic from freely flowing to queued conditions and from queued to freely flowing conditions was studied along a 14-km section of German Autobahn 9 near Munich. Several bottlenecks were identified by a systematic examination of the excess vehicle accumulation and excess travel time (delay) that arose between measurement locations. It is shown that a bottleneck arose repeatedly downstream of an on-ramp on a busy freeway. The analysis tools used were curves of cumulative vehicle arrival number versus time and curves of cumulative time-averaged velocity versus time. The data required to construct these curves were available in archived form from inductive loop detectors embedded in the freeway. These cumulative plots were carefully and systematically transformed to produce the resolution necessary to reveal important details of the evolution of traffic flow features. These high-resolution transformed curves have made it possible to identify key time-dependent features related to the activation and deactivation of the bottleneck.
First In, First Out Properties of a Commodity-Based Kinematic Wave Simulation Model
Authors: Jin Wen-Long , Jayakrishnan R.
Published: May 2018

Computational efficiency and first in, first out (FIFO) are both important issues in applications such as dynamic traffic assignment. This paper first shows by example the FIFO properties of a computationally efficient commodity-based kinematic wave (CKW) model of network traffic flow. After the development of measurements of FIFO violation among commodities in location and time on the basis of the misplacement of vehicles in total and commodity traffic, it is argued theoretically that numerical CKW solutions converge to FIFO ones. Then, with numerical examples, it is shown that FIFO violation in CKW solutions is a function of the simulation time and the number of commodities but decreases with decreasing cell lengths, even for infinite number of commodities. Finally, the possible implications of this study are discussed.
Using the Ant Algorithm to Derive Pareto Fronts for Multiobjective Siting of Emergency Service Facilities
Authors: Liu Nan , Huang Bo , Pan Xiaohong
Published: May 2018

Efficient and timely response during accidents has received increased attention from practitioners and researchers. The siting of emergency service facilities (ESFs) plays a crucial role in determining the efficiency of safety protection and emergency response. This paper explores a novel multiobjective ant algorithm for the siting of ESFs. With the aid of the geographic information system, the algorithm finds a population of solutions, uses Pareto ranking to sort these solutions, and derives the Pareto front. It is demonstrated that the algorithm successfully captures a pool of nondominated solutions and thereby provides decision makers with a set of alternative solutions. The case study also demonstrates how decision makers may choose one “best” solution from the pool according to their preference or determinant criteria.
Q-Learning for Flexible Learning of Daily Activity Plans
Authors: Charypar David , Nagel Kai
Published: May 2018

Q-learning is a method from artificial intelligence to solve the reinforcement learning problem (RLP), defined as follows. An agent is faced with a set of states, S. For each state s there is a set of actions, A( s), that the agent can take and that takes the agent (deterministically or stochastically) to another state. For each state the agent receives a (possibly stochastic) reward. The task is to select actions such that the reward is maximized. Activity generation is for demand generation in the context of transportation simulation. For each member of a synthetic population, a daily activity plan stating a sequence of activities (e.g., home-work-shop-home), including locations and times, needs to be found. Activities at different locations generate demand for transportation. Activity generation can be modeled as an RLP with the states given by the triple (type of activity, starting time of activity, time already spent at activity). The possible actions are either to stay at a given activity or to move to another activity. Rewards are given as “utility per time slice,” which corresponds to a coarse version of marginal utility. Q-learning has the property that, by repeating similar experiences over and over again, the agent looks forward in time; that is, the agent can also go on paths through state space in which high rewards are given only at the end. This paper presents computational results with such an algorithm for daily activity planning.
Practical Approach to Criteria for the Use of Lime–Fly Ash Stabilization in Base Courses
Authors: Barstis William F. , Metcalf John
Published: May 2018

In October 2000 the Mississippi Department of Transportation (MDOT) initiated a study to evaluate the long-term performance of lime–fly ash (LFA) stabilized soil as a base course material. This study entailed performing falling weight deflectometer (FWD) tests on both newer and older pavements and coring pavement at each FWD location to observe the condition of the layers, to obtain pavement thicknesses, and to perform unconfined compressive strength (UCS) testing. Visual observation, backcalculated modulus, and in situ structural layer coefficient values showed that MDOT LFA-stabilized soil base courses have highly variable material properties and thicknesses. Recommendations were made to increase the average LFA material property values and to reduce the spread in these values by increasing the required compaction of the LFA-stabilized soil base layer to 100% standard Proctor effort, setting the required in situ Proctor UCS at 400 psi, and reducing variability by either improving the current method of field-mixed-in-place stabilization or requiring plant-mixed material with placement of the blended material via a paver. It is further recommended to increase the typical LFA-stabilized soil base layer design thickness from 6 to 8 in. and to use a 6-in. chemically stabilized subgrade layer to provide additional support to the pavement structure.
Stabilization Techniques for Unpaved Roads
Authors: Bushman William H. , Freeman Thomas E. , Hoppe Edward J.
Published: May 2018

An amendment to Virginia House Bill 1400, Item 490, No. 1h, calls for the Virginia Transportation Research Council to “continue its evaluation of soil stabilizers as an alternative to paving low-volume secondary roads.” In response, promising soil stabilization products were evaluated with the relatively new technique of deeply mixing chemical additives into unpaved roadbeds. This work is based on the construction of a 1.75-m-long trial installation on Old Wheatland Road in Loudoun County, where seven commercially available stabilization products were applied to the unpaved road. A rigorous evaluation of treatment performance will provide the basis for recommendations to the Virginia Department of Transportation's operating divisions regarding improvements to the maintenance practices for gravel roads. Results thus far indicate that the introduction of soil stabilizers through deep mixing is a promising technique. The life-cycle cost analysis indicates that constructing a standard bituminous surface-treated roadway and maintaining it as such is much more cost-effective than using any of the products in this trial. Further, the analysis indicates that using the bituminous surface treatment alternative is also much more cost-effective than maintaining an unpaved road.
Structural Contribution of Geosynthetic-Reinforced Working Platforms in Flexible Pavement
Authors: Kim Woon-Hyung , Edil Tuncer B. , Benson Craig H. , Tanyu Burak F.
Published: May 2018

A study was conducted in the field and with a large-scale model experiment (LSME) to evaluate the structural contribution of a 0.30-m-thick geosynthetic-reinforced granular layer used as a working platform for construction over soft subgrade. The study was conducted in the context of the 1993 AASHTO design guideline, in which the structural number (SN) of the pavement is based on layer coefficients (each defined using a resilient modulus). Working platforms reinforced with geosynthetics had smaller elastic deflections and larger elastic moduli than unreinforced working platforms with the same thickness. Reinforcement factors obtained in the field ranged from 1.2 to 1.8; those obtained in the laboratory ranged from 1.7 to 2.0, with greater reinforcement factors for the less extensible geosynthetics (geogrid, woven geotextile) for a 0.3-m-thick granular working platform. Of the four geosynthetics tested, the geogrid resulted in the greatest increase in modulus. Reinforcing the working platforms with geosynthetics resulted in increases in layer coefficients ranging from 50% to 70%. Similarly, increases in SN for a typical pavement structure were realized, ranging from 3% to 11% when all other factors were equal.
Field Installation and Pullout Test of Embedded Suction Anchors
Authors: Bang S. , Boonyong S. , Cho Y.
Published: May 2018

The field installation and pullout tests of an embedded suction anchor were conducted inside the Okpo Harbor located along the southeastern coast of South Korea in 2003. The embedded suction anchor was made of steel with an outside diameter of 1.91 m, length of 2.5 m, and thickness of 3 cm. It was installed by a 9.25-m-long suction pile attached at the top of the anchor. During installation of the embedded suction anchor and retrieval of the suction pile, the water pressure inside the suction pile versus the pile embedded length relationship was carefully measured. In addition, during the embedded suction anchor pullout test, the load versus anchor vertical displacement relationship was measured. The measured pullout capacity was then compared with the analytical prediction. The analytical solution was selected from various available solutions of deeply embedded plate anchors available from the literature through detailed comparisons with the results from geotechnical centrifuge model tests on embedded suction anchors. Comparison indicated that the predicted embedded suction anchor resistance matched reasonably well with the field test result.
Permeability of Base Material for Maine Roads
Authors: Bouchedid Michel B. , Humphrey Dana N.
Published: May 2018

Cutting the cost of road maintenance and reducing life-cycle costs are the main reasons the FHWA has increased its emphasis on drainage in the pavement structural section. Good drainage requires that the base and subbase drain freely and relatively quickly. Poor drainage is thought to cause the Maine Department of Transportation (MaineDOT) to spend millions of extra dollars each year maintaining its state highways. Improved specifications and design policies for subbase material were developed by investigating the gradation and permeability of the subbase currently used by MaineDOT. Eight field projects were selected to investigate the permeability and gradation of subbase material for Maine roads. Results indicate that typical MaineDOT subbase gradations have excess fines and sand-size fraction compared with FHWA recommendations. The standard subbase currently used by MaineDOT has an average coefficient of permeability of 5.9 × 10−4 cm/s (1.7 ft/day) whereas the FHWA recommends a minimum coefficient of permeability of 0.35 cm/s (1,000 ft/day) for permeable base material. With multivariable regression analysis, an equation was determined to estimate subbase permeability from percent fines and coefficient of uniformity. Life-cycle cost savings of up to $244,000/km ($406,000/mi) of road can be achieved in Maine with the use of permeable base.
Evaluation of Liquefaction Potential Using Neural Networks Based on Adaptive Resonance Theory
Authors: Kurup Pradeep U. , Garg Amit
Published: May 2018

The incomprehensible loss of lives and extensive damages to transportation facilities caused by earthquakes emphasize the need for robust and reliable methods for evaluating the liquefaction potential of sites. Traditional methods for evaluating liquefaction potential are based on correlating data from the standard penetration test (blow count, N), cone penetration test (cone resistance, qc), or the shear wave velocity ( Vs) with the cyclic stress ratio. These methods are unable to incorporate the complex influence of various soil and in situ state parameters. This problem encouraged the development of numerous nontraditional methods such as artificial neural networks that try to learn and account for the influence of various soil and in situ state properties. The possibility of using neural networks based on adaptive resonance theory (ART) for the prediction of liquefaction potential was explored. These networks have been shown to be far more efficient and reliable than the commonly used backpropagation artificial neural network and other multilayer perceptrons. Two Fuzzy ARTMAP (FAM) models were developed and tested with qc and Vs data obtained from past case histories. The qc-and Vs-based FAM models gave overall successful prediction rates of 98% and 97%, respectively. The promising results obtained by the FAM models exemplify the potential of nontraditional computing methods for evaluating liquefaction potential.
Passengers and Other Factors Affecting the Safety of Young and Older Drivers
Authors: Padlo Patrycja , Aultman-Hall Lisa , Stamatiadis Nikiforos
Published: May 2018

The specific objective of this study was to assess the relative propensity of young (16 to 20 years old) or older (65 years and older) drivers in Connecticut to be at fault in a traffic crash when they ( a) travel at night, ( b) travel on different classes of roadway (freeway versus state route versus local road), and ( c) travel with different numbers of passengers. For young drivers, the age of the passengers was also considered. The quasi-induced exposure technique was used with police-reported crashes between 1997 and 2001. The results show that young driver risk increases at night, on freeways (and for single-vehicle crashes on local roads), as well as with increased numbers of passengers. For older drivers the risk also increases at night and on freeways (and for single-vehicle crashes on local roads); however, older drivers are less likely to cause crashes when traveling with passengers. These results suggest that the new graduated driver licensing restrictions in place in Connecticut will reduce crashes and that there is the potential to improve young driver safety further by extending these restrictions. Furthermore, similar regulations or education programs aimed at older drivers might improve crash experience for these individuals, especially those older than 75.
Effects of Human–Machine Interface Design for Intelligent Speed Adaptation on Driving Behavior and Acceptance
Authors: Rook Arno M. , Hogema Jeroen H.
Published: May 2018

The effects of human–machine interface (HMI) design for intelligent speed adaptation (ISA) on driving behavior and acceptance were measured in a moving-base research driving simulator. Sixty-four experienced drivers participated in two simulator experiments (32 in each). During the simulated runs with ISA, the speed limit was communicated through the ISA system. The ISA system consisted of an indication of the speed limit on the speedometer and a gas pedal that could be used either as a haptic or tactile pedal or as a dead throttle. Two versions of the haptic gas pedal were examined in Experiment I: a low-force ISA (easy to overrule, informative in nature) and a high-force ISA (stronger counterforce, more compulsory in nature). Two other configurations were tested in Experiment II: a tactile pedal (a vibration on the gas pedal, informative in nature) and a dead throttle (completely restraining the driver from exceeding the speed limit). It was hypothesized that the closer the ISA is to an informative type, the higher the acceptance and the smaller the effects on driving behavior would be. This hypothesis appeared to be valid, although for both driving behavior and acceptance, not all four HMIs could be ranked unambiguously on the scale from no ISA to full ISA. In sharp curves, drivers appeared to choose a driving speed below the speed limit, irrespective of ISA. The specific road environment scenarios that were inserted to examine presupposed compensatory behavior for experienced delay indicated no signs of compensatory driving behavior.
Assessing Message Display Formats of Portable Variable Message Signs
Authors: Wang Jyh-Hone , Cao Yong
Published: May 2018

A study on the message display formats of portable variable message signs (VMSs) is presented. Through a series of laboratory driving simulation experiments, the influences of the interaction between display format and number of message lines and driving lanes were investigated. In the simulation, digitally created VMS stimuli were inserted into a driver's-view driving video, and the video was projected onto a screen in front of a stationary vehicle. Eighteen subjects from three age groups with balanced gender participated in the experiments. Each subject, sitting in the driver's seat of the vehicle, was required to make proper responses signaling comprehension of the VMS stimuli. Subjects’ responses and accuracy were recorded in a database. On the basis of the statistical analysis of the collected data, it was found that discretely displayed messages took less response time than sequentially displayed messages. Singleline messages were better than multiple-line messages. Motorists could better view portable VMSs when they were driving in the outer lane. It was also found that older drivers exhibited slower response and less accuracy than younger drivers; women drivers exhibited slower response but higher accuracy than men drivers.
Validation of a Driving Simulator for Work Zone Design
Authors: Bella Francesco
Published: May 2018

The research project aimed at calibrating and validating the driving simulator of the European Interuniversity Research Center for Road Safety to enable its use for design and verification of the effectiveness of temporary traffic signs on highways. The research was developed through the following steps: ( a) a survey of speed measurements on highways next to a work zone of medium duration, ( b) reconstruction in virtual reality of the real situation by using the driving simulator and subsequent running of a series of driving tests, and ( c) statistical analysis of the field speeds and of the speeds from driving simulations for validation of the simulator. The surveyed work zone was located on Highway A1 from Milan to Naples, Italy. Speed measurements were conducted with a laser speed meter in the transition area, the activity area, and the termination area, and in the advance warning area speeds were shot with a camera from an overpass. Speed data from the field and the simulator were analyzed by using the bilateral Z-test for non-matched samples to determine whether drivers responded differently in the simulator compared with their response during the real driving experience. The activity carried out revealed that differences between the speeds observed in the real situation and those measured with the simulator were not statistically significant.
Evaluation of Biometric Technologies for Access Control at Transportation Facilities and Border Crossings
Authors: Nakanishi Yuko J. , Western Jeffrey
Published: May 2018

To ensure that only authorized individuals–-legitimate workers, travelers, and visitors–-enter a transportation facility or border crossing, their identities must be ascertained. Because manual procedures are time-consuming, resource intensive, and vulnerable to human error and manipulation, the use of biometric technologies should be considered. This paper discusses several biometric technologies–-fingerprint recognition, iris recognition, facial recognition, and hand geometry–-and assesses their feasibility for use in access control at transportation facilities and border crossings. The advantages and disadvantages of the technologies are provided, as are cost, accuracy, and other performance data. Potential privacy and data issues are also discussed.
Conversions of Wide Curb Lanes
Authors: Hunter William W. , Feaganes John R. , Srinivasan Raghavan
Published: May 2018

This paper examines the operational effects of converting a 14-ft-wide curb lane to an 11-ft-wide travel lane with a 3-ft-wide undesignated lane at various locations in Broward County, Florida. Six midblock sites with various configurations were selected for study. Two of the midblock sites had previously been striped with the 3-ft undesignated lane, and these served as comparison sites. Videotapes were taken of bicyclists riding through the midblock and intersection locations before and after placement of the 3-ft undesignated lane striping. At the locations where the 3-ft stripe was already in place, the videotaping was done to examine whether changes were occurring over time. Software was used to extract images at all midblock locations so that before and after lateral spacing measurements could be obtained. After the new striping, ( a) bicycles were ridden, on average, 7 to 9 in. further away from the gutter pan seam; ( b) motor vehicles were driven, on average, 6 to 12 in. farther away from the gutter pan seam; ( c) passing motor vehicles were driven, on average, 3 to 5 in. closer to bicycles at curb and gutter sites; conversely, passing motor vehicles were driven, on average, 4 to 5 in. farther away from bicycles at the sites where the stripe was already in place; and ( d) the addition of the stripe at new locations had the effect of reducing the amount of motor vehicle encroachment into the adjacent lane on these multilane roadways.
Determination of Pedestrian Push-Button Activation Duration at Typical Signalized Intersections
Authors: Noyce David A. , Bentzen Billie Louise
Published: May 2018

Recent advances in pedestrian push-button design, led by the development of accessible pedestrian signals (APSs), have created a new method of communicating traffic control information to pedestrians. Some APS devices have beaconing features or verbal (speech) message capabilities obtained by pressing and holding the pedestrian push button for approximately 3 s. Other features, such as the extension of the walk interval, may also be activated with an extended press of the push button. Recent research has suggested that 3 s may be excessive because it is hard for some users to hold the push button for this long. Additionally, most pedestrians may not hold the push button for this length of time. The problem lies in determining how long the APS push button should be pressed for a push-button information message or special accessibility features to be obtained. The primary objective of the research described in this paper was to develop a time distribution of typical pedestrian push-button activation durations. Data were obtained by attaching a voltage recorder to the pedestrian push-button circuit inside traffic signal controllers at eight locations in three cities in Wisconsin and Massachusetts. This device recorded the amount of time, to the nearest 1/100 of a second, that each pedestrian push button was pressed. A total of 1,439 push-button presses were recorded. The average push-button press duration was 0.2 s. More than 95% of all push-button presses recorded were less than 1.0 s. Only four push-button presses exceeded 3.0 s. The results show that the duration of an extended push-button press needed to obtain additional crossing information can be reduced to approximately 1 s without a significant number of false calls. A 1-s press will minimize the effort required for pedestrians to actuate special accessible features, while it will minimize unnecessary noise and vehicular traffic disruption.
Case Study Analysis of Pedestrian and Bicycle Data Collection in U.S. Communities
Authors: Schneider Robert J. , Patten Robert S. , Toole Jennifer L.
Published: May 2018

Federal funding for pedestrian and bicycle transportation has increased over the past 15 years, with a resulting increase in shared-use pathways, paved shoulders, bicycle lanes, and sidewalks in many parts of the United States. This has caused communities to ask questions: Where is pedestrian and bicycle activity taking place? What effect does facility construction have on levels of bicycling and walking? What are the characteristics of nonmotorized transportation users? How many miles of pedestrian and bicycle facilities are available? Where are existing facilities located? This paper provides a summary of recent research that was sponsored by FHWA and the Pedestrian and Bicycle Information Center to review and evaluate bicycle and pedestrian data collection methods throughout the United States. It uses a case study approach to evaluate pedestrian and bicycle data collection in 29 different agencies throughout the country in communities ranging in size from 6,000 residents (Sandpoint, Idaho) to 8 million residents (New York City). These case studies are analyzed in the following data collection categories: manual counts, automated counts, surveys targeting nonmotorized transportation users, surveys sampling a general population, inventories, and spatial analyses. The results provide information about the methods and the optimum timing for pedestrian and bicycle data collection; emerging technologies that can be used to gather and analyze data; the benefits, limitations, and costs of different data collection techniques; and implications for a national data collection strategy.
Optimization for Pedestrian and Vehicular Delay in a Signal Network
Authors: Bhattacharya Prabhati , Virkler Mark R.
Published: May 2018

The efficiency of an arterial network can be enhanced by optimizing the user costs incurred because of delays and other socioeconomic factors. Until recently, research mostly focused on minimizing vehicular delay to optimize user costs. Currently, no signal coordination tool exists to balance delays to both vehicles and pedestrians. A methodology that uses known techniques and available tools to identify an optimal signal coordination plan is developed. Pedestrian delay patterns are obtained from previous research. Delay data for vehicles are based on the modeling of peak-hour traffic conditions in urbanized areas of a hypothetical city. The signal optimization software Synchro (Version 3.2) was used to investigate the variations in vehicle delay with different signal coordination plans and offsets. The results reveal that the best offsets for vehicles and pedestrians are not necessarily the same. Consequently, a signal coordination plan that would benefit both should consider the total user costs of the system. The results show that the highest total pedestrian delay can spike up the user costs more than the highest total vehicular delay. The offset that generates the optimal user cost can be different from the best offset for vehicles or pedestrians. Thus, a balance between pedestrian delay and vehicular delay can be achieved to arrive at an optimal signal coordination plan.
Quantification of Pavement Damage Caused by Dual and Wide-Base Tires
Authors: Elseifi Mostafa A. , Al-Qadi Imad L. , Yoo Pyeong J. , Janajreh Ibrahim
Published: May 2018

A study conducted in 2001 on the heavily instrumented Virginia Smart Road measured pavement responses to a new generation of single wide-base tire (445/50R22.5) and to dual tires (275/80R22.5). The new single wide-base tire has a wider tread and a greater load-carrying capacity than conventional wide-base tires. The potential fatigue damage resulting from different tire configurations was evaluated. After successful field testing, a finite element (FE) parametric study was conducted to investigate different failure mechanisms that were not evaluated in the field. In this study, dual tires and two new generations of wide-base tires (445/50R22.5 and 455/55R22.5) were evaluated. The main difference between the two generations of wide-base tires is that the 455/55R22.5 is wider than the 445/50R22.5; hence, it further reduces the contact stress at the pavement surface under the same nominal tire pressure. In the developed FE models, geometry and dimensions were selected to simulate accurately the axle configurations typically used in North America; actual tire tread sizes and applicable contact pressure for each tread were considered; laboratory-measured pavement material properties were incorporated; and models were calibrated and properly validated against stress and strain measurements obtained from the experimental program. Four failure mechanisms were considered: fatigue cracking, primary rutting, secondary rutting, and top-down cracking. Results indicated that the new generations of wide-base tire would cause the same or relatively greater pavement damage than conventional dual tires. Because overall truck weight is reduced by approximately 450 kg when wide-base tires are used, it is reasonable to implement the load limits currently applied to the dual-tire assembly on the 455/55R22.5 wide-base tire.
Estimating Extended Idling Emissions of Heavy-Duty Diesel Trucks in Texas
Authors: Zietsman Josias , Perkinson Dennis G.
Published: May 2018

Long-haul truck drivers idle their vehicles to operate heating systems and air conditioners, generate electricity, charge the vehicles’ batteries, and warm up the engines. This type of idling, which often occurs over extended periods and could be a significant source of emissions, is expected to increase because of the U.S. Department of Transportation's latest rule mandating that truck drivers rest 10 h for every 14 h of driving. The emissions associated with this type of discretionary idling occurring at the beginning and end of trips are not included in emissions inventories and can be an important contributor to the overall mobile source emissions. There is, therefore, a need to develop a procedure that would yield accurate estimates of extended truck idling emissions. This study developed such a methodology by using a nonattainment area in Texas as a pilot study. On the basis of interviews and observations made at generators such as truck stops, public rest areas, industries, ports, and intermodal facilities, a model was developed to perform the emissions estimates. The procedure was applied to the remaining metropolitan areas in Texas. It was found that extended truck idling emissions were a major source of mobile source emissions, resulting in emissions of more than 30 tons per day of oxides of nitrogen and more than 0.8 ton per day of particulate matter in Texas metropolitan areas. Although these emissions represent less than 4% of the overall on-road mobile source emissions, they are important in assisting nonattainment areas to reach conformity.
Microprocessor Signal and Train Control
Authors: Hartong Mark W. , Cataldi Olga K.
Published: May 2018

In February 2005, the Federal Railroad Administration issued a set of new regulations governing the development and use of microprocessor-based signal and train control systems. The new rule represented a major paradigm shift from prescriptive to performance-based regulation. This paper addresses the rationale for that paradigm switch, highlights the key points of the rule that go into the safety case, and discusses the impact of the new regulatory approach on the rail industry.
Safety Assessment of Information Delay on Performance of Intelligent Vehicle Control System
Authors: Liu Yu , Dion François , Biswas Subir
Published: May 2018

Recently, increasing attention has been put on the use of automated vehicle control systems to reduce traffic crashes due to driver errors. Proposed systems rely on either onboard range sensors or vehicle-to-vehicle wireless communications to obtain pertinent information about surrounding vehicles and to determine appropriate acceleration or deceleration commands. Although numerous studies have used microscopic traffic simulation to study the effects that these systems might have on traffic flows, generally these studies did not consider all factors that may affect their operation. A particular element that has been ignored is delay in data acquisition. Using a microscopic traffic simulation model that was developed to simulate intelligent transportation system applications relying on the use of onboard vehicle sensors or wireless transmissions, this paper attempts to quantify the safety effects created by the use of delayed information in automated vehicle control systems. The study clearly indicates that information delay affects the operation of vehicle control systems, particularly when sensor or transmission delays result in the use of information older than a certain threshold, found in this case to be 0.5 s.
Vehicle Segmentation and Tracking in the Presence of Occlusions
Authors: Kanhere Neeraj K. , Birchfield Stanley T. , Sarasua Wayne A.
Published: May 2018

A novel method is presented for visually monitoring a highway automatically when the camera is relatively low to the ground and on the side of the road. In such a case, occlusion and the perspective effects that are due to the heights of the vehicles cannot be ignored. By using a single camera, the system automatically detects and tracks feature points throughout the image sequence, estimates the 3-D world coordinates of the points on the vehicles, and groups those points together to segment and track the individual vehicles. Experimental results on different highways demonstrate the ability of the system to segment and track vehicles even in the presence of severe occlusion and significant perspective changes. By handling perspective effects, the approach overcomes a limitation of commercially available machine vision-based traffic-monitoring systems that are used in many intelligent transportation systems (ITS) applications. Researchers are targeting this system as a step toward a next-generation ITS sensor for automated traffic analysis.
Effect of Sensor Spacing on Performance Measure Calculations
Authors: Fujito Iris , Margiotta Rich , Huang Weimin , Perez William A.
Published: May 2018

State and local departments of transportation (DOTs) increasingly deploy road detectors, such as inductive loops, to monitor congestion on their road networks. As deployment increases, the operating and maintenance cost associated with these detector systems will become issues for many state DOTs. Agencies will need to decide where to add new detectors and which detectors should continue receiving maintenance, given their resource constraints. For data collected from these sensors to remain meaningful, traffic data quality should not be adversely affected in these decisions. The needed traffic data quality depends on the data's intended purposes. An empirical study was conducted to address the impact of sensor spacing along freeway corridors on the computation of performance measures such as travel time index. The scenario that has the smallest sensor spacing (greater density of sensors) is considered to capture actual traffic conditions most closely. If sensor spacing is increased, how will the quality of the traffic data be affected? The results showed that when sensors were deleted relative to the baseline sensor spacing condition, the congestion measure statistic varied. This congestion measure did not become “worse” as more sensors were deleted. Instead, sometimes one spacing pattern overestimated the measure, and at other times another spacing pattern underestimated this measure. The analysis showed that the location of the sensors is important in the estimation of congestion for the corridor.
Using Automatic Vehicle Identification Data to Gain Insight into Travel Time Variability and Its Causes
Authors: Li Ruimin , Rose Geoffrey , Sarvi Majid
Published: May 2018

Unreliable transport systems cause stress and anxiety for travelers and create difficulties for authorities managing network operations. This study conducted a comprehensive investigation of travel time distributions in terms of various time windows based on extensive automatic vehicle identification data collected from the CityLink Tollway in Melbourne, Australia. The study also examines the components of travel time variability and explores their relationships. Given the number of factors affecting travel time variability and their interaction effects, multiple regression analysis is used to quantify the contribution of the various sources to the variability in travel time. Application of the methodology to two groups of data—namely, travel times in morning peak and afternoon peak—demonstrates that they have distinctive sources of variability. Morning peak travel times vary mostly because of driver-related factors, specifically lane choice decisions, whereas 25% of the variability of travel times in the afternoon peak corresponds to capacity-related factors.
Cellular-Based Data-Extracting Method for Trip Distribution
Authors: Pan Changxuan , Lu Jiangang , Di Shan , Ran Bin
Published: May 2018

With the rapid development of cell phone–locating technologies, traffic data–extracting methods through cell phones start to play an important role in urban transportation planning and network analysis. This study investigates a cellular-based method to extract trip distribution data for urban transportation planning. In this method, the trip distribution table is generated as output with input of spatiotemporal information retrieved from cell phone subscribers. An experiment adopting this method has been implemented in China to test the feasibility of the method. The favorable outcomes obtained from the experiment exhibit high practicability and effectiveness of the proposed method.
Sensitivity of NCHRP 1-37A Pavement Design to Traffic Input
Authors: Papagiannakis A. T. , Bracher M. , Li J. , Jackson N.
Published: May 2018

This study deals with the sensitivity of the NCHRP 1-37A Pavement Design Guide predictions to traffic data input. A number of traffic data collection scenarios are simulated with the use of extended coverage (more than 299 days per year) weigh-in-motion (WIM) data from the Long-Term Pavement Performance (LTPP) database. These scenarios consist of combinations of site-specific, regional, and national data, including total truck counts, truck counts by class, and axle-load distributions by axle type. For each simulated scenario, traffic input to the NCHRP 1-37 Pavement Design Guide is estimated with the methodologies prescribed in the Traffic Monitoring Guide. For discontinuous time coverage scenarios, all possible time coverage combinations are considered, and the range in the estimated traffic input parameters is computed. Pavement life predictions are obtained under mean traffic input for all traffic data collection scenarios and under low percentile input for the discontinuous traffic data collection scenarios. For each scenario and confidence level, pavement life errors are predicted for the life estimated by the complete extended coverage WIM data set. Two sources of error are identified: one from specifying the mean value for all traffic input and one from specifying the lowest percentile for all traffic input simultaneously (the latter applies to discontinuous coverage scenarios only). Overall error is computed by the addition of the range in the mean of the second error component to the range of the first error component. The results are in the form of plots of pavement life prediction error, versus confidence level, versus traffic data collection scenario.
Accuracy and Precision of Typical Quality Measures
Authors: Burati James L. , Weed Richard M.
Published: May 2018

Computer simulation studies were performed to evaluate the accuracy and precision of the estimators for three quality measures: percent within limits (PWL), average absolute deviation (AAD), and conformal index (CI). Sample sizes of 3, 5, and 10 were simulated for various levels of actual population PWL, AAD, or CI. The estimators for all three quality measures exhibited similar trends for the variabilities of their respective individual estimates. For each estimator, the variability decreased as the sample size increased. For PWL, the variabilities increased as the actual population PWL departed from either 0 or 100 PWL, peaking at 50 PWL. For AAD and CI, the variabilities increased as the actual population value, AAD or CI, departed from 0. Both PWL and AAD were unbiased estimators of their respective population parameters. However, the CI appeared to be a biased estimator, consistently underestimating the true population CI. Since the CI offers no benefits compared to AAD, and since it appears to be a biased estimator, AAD is preferred to the use of CI. In this study, PWL and AAD exhibited similar trends, so it is difficult to conclude that either method is preferred on the basis of bias and precision. Although there are many other differences between PWL and AAD, since they exhibited similar trends this study shows that the decision to choose PWL or AAD will need to be based on factors other than the bias and precision of their respective estimators.