bluuebunny/crossref_metadata_2025 huggingface dataset:
Paris-Lexington Road: Integration of Intrinsic Qualities, Civics of Design, and Computer Technology
Authors: Oost Dennis A. , Thomas Ron , Jones Grant R.
Published: August 2018

Integration of intrinsic landscape qualities, democratic public participation, and computer technology in a highway design process are described in this study of a road improvement project. Since 1967, there had been constant conflict over improvement of the historic Paris Pike between Lexington and Paris, Kentucky (U.S. 27 and 68). After 25 years, the concerned parties came together and signed a Memorandum of Agreement (MOA) that moved the project out from under a court-ordered injunction and laid out the conditions for finding a mutually agreeable plan for improving the 19.3-km (12-mi) road corridor renamed the Paris-Lexington Road. Construction of the first 4.8 km (3 mi) of the corridor at the Paris end will begin after 1 year of work by the Kentucky Transportation Cabinet, the 12-member Governor-appointed task force of MOA signers, and intensive design and engineering work carried out by the multidisciplinary design team working directly with the community in an extraordinary public process that included all the property owners in the corridor. The plan has the consensus support of the task force and the carefully and thoughtfully negotiated acceptance by the property owners. It reflects the flexibility of Green Book minimum criteria being applied to a very sensitive roadway corridor, the importance of the roadway fit and flow with the landscape, and the benefits of using computer technology to clarify communication with affected citizens. The new Paris-Lexington Road will be a scenic commercial and historic parkway that will be a treasure to all of Kentucky.
British Methods for Improving Sensitivity of Bridge Designers to Good Bridge Appearance
Authors: Wallsgrove Jon
Published: August 2018

In Britain, there is a two-pronged attack to win design excellence: encourage the best and eliminate the worst. This study describes ways in which the Highways Agency encourages adoption of design excellence in its bridge projects. One is the formal review of designs by the Royal Fine Art Commission and the principal architect-planner, and through public consultations and inquiries. Published advice, including a book on detailed aspects of bridge appearance, is also considered. Further, encouragement of good design is given through conferences to discuss bridge aesthetics, debates in the press and in meetings, publicity as to the government's interest in good design, and design competitions. Finally, new initiatives are outlined: design excellence in design-and-build schemes, broader scope with design, build, finance, operate, revival of masonry and unreinforced concrete, and new technology.
Computational Driver Model in Transport Engineering: COSMODRIVE
Authors: Tattegrain-Veste Hέlène , Bellet Thierry , Pauziέ Annie , Chapon Andrέ
Published: August 2018

With regard to road safety issues, a deep understanding of the driver as a logic system is crucial to predict the most probable behavior according to the contextual elements. Knowledge and data about human functional abilities exist. But the problem is to organize and structure them. The development of a computational approach in driver modelization is addressed. In the first part, a brief historical overview is presented of available driver models in ergonomics and psychological areas, and the distinction between predictive and explicative models in an implementation perspective is the focus. In the second part, the computational aspect of the work is described, along with the software concepts, the cognitive modeling needs, and the implementation choices. Object-oriented techniques were chosen because they provide a modular overview of the general system and offer a convenient representation of cognitive processes. Object-oriented formalism, in particular object modeling technique diagrams, acts as a bridge between the two domains of computer science and the human sciences. The objective is to determine whether it is possible to implement reliably a driver model using the techniques from artificial intelligence and based on the theoretical knowledge from cognitive sciences research. This attempt to establish links between different scientific domains, requiring a common tool, is a challenge. A first step of a work that will have to be developed in a long-term time scale, taking into account its quite ambitious objective, is described.
Immediate and Long-Term Effects of Glare from following Vehicles on Target Detection in Driving Simulator
Authors: Ranney Thomas A. , Masalonis Anthony J. , Simmons Lucinda A.
Published: August 2018

Nine hypotheses concerning the immediate and long-term effects of glare were tested in a fixed-base truck simulator. Eight subjects completed two 4-hr sessions. During one session, simulated headlight glare from following vehicles was presented intermittently in the cab's side mirrors. Designated targets, including pedestrians and vehicles in the mirrors, were presented at the beginning, middle, end, or 5 sec following glare episodes. Response times and accuracy for detecting targets were recorded. Target detection in the presence of glare was slower than in the absence of glare. Pedestrians appearing in the middle of a glare episode were detected faster than those appearing at glare onset, indicating adaptation to glare. Target detection following a 5-sec recovery period was faster than for targets appearing immediately following the glare episode. A longer recovery period did not provide an additional benefit. Glare episode duration did not affect target-detection speed following the glare. Performance did not deteriorate over the course of the glare session, indicating no cumulative effect of glare on target detection. Overall, the impairment effects associated with glare were not as strong and consistent as in previous laboratory studies. Differences in attentional demands between laboratory studies and driving were used to explain these differences.
Self-Reported Exposure and Crash Involvement in Large Sample of Ontario Drivers Aged 79 Years and Over
Authors: Tasca Leo L.
Published: August 2018

The Ministry of Transportation of Ontario conducted a pilot study to evaluate the effectiveness of a group education and information session for drivers aged 80 and over. Questionnaires on older drivers' self-awareness of risk were completed by 1,163 drivers aged 79 and over. The questionnaire asked several rudimentary questions about self-reported exposure and crash involvement. Answers to these questions are used to estimate the amount of driving and the frequency of crash involvement for very old drivers. The respondents' self-reports of the distance and days driven during the previous week and the number of crashes within the past 5 years are cross-classified by gender, age, season, examination center location, household size, self-reported medical condition, and self-reported medication use. The best predictors of self-reported distance driven during the previous week are gender, age, and the location of the driver examination center (the latter variable is a proxy for geographic location). The best predictors of self-reported crash involvement during the previous 5 years are the presence or absence of a self-reported medical condition and two variables used as proxies for the amount of driving. The results of a logistic regression analysis indicate that drivers reporting both a current medical condition and more driving exposure have a substantially higher crash risk. However, important limitations stem from the use of self-report data and the absence of data on the onset of a medical condition. These results, therefore, are tentative at best.
Age-Based Road Test Policy Evaluation
Authors: Lange James E. , McKnight A. James
Published: August 2018

The per-driver accident rates of states with age-based license renewal testing were compared with those of neighboring states without such testing. In states requiring age-based skill testing, tested drivers evidenced significantly lower (7 percent) relative involvement in injury accidents than their counterparts in the comparison states. However, the difference was confined to accident involvement and did not appear in single-vehicle accidents, for which the elderly drivers were more clearly responsible. Although age-based skill testing is associated with accident reduction among the drivers tested, it is unclear if such testing induces the affected individuals to drive less frequently rather than removing unsafe drivers from the road. The results call into question the ability of age-based renewal testing to yield significant reductions in proportions of unsafe drivers among the elderly.
Development and Benefits of Computer-Aided Travel Time Data Collection
Authors: Benz Robert J. , Ogden Michael A.
Published: August 2018

Link travel times are one of the most widely used and valuable measurements of congestion. Travel time measures are compatible with multimodal analyses and are understood by nontechnical audiences, yet are rigorous enough for technical analyses by transportation engineers and planners. The “average” car and floating car techniques are the most widely used travel time–based measures. Although there are cost, safety, and data limitation problems associated with collecting travel time data manually, the use of computer-aided travel time technology solves most of these problems. Detailed speed, time, and distance information can be safely collected in up to 0.1-sec intervals for a reasonable cost. The consistent format of the computer data lends itself to an automated analysis process. The development and benefits of using computer-aided travel time data collection techniques using distance-measuring instruments (DMI) and laptop computers are discussed. Automated analysis techniques and developmental software can produce results such as speed profiles, average speeds, level of service, and vehicle accelerations. Current and future research on air quality methods, fuel consumption information, and planning model potential is also presented.
Advanced Techniques for Travel Time Data Collection
Authors: Turner Shawn M.
Published: August 2018

Travel time information is becoming more important for applications ranging from congestion measurement to real-time travel information. Several advanced techniques for travel time data collection are discussed, including electronic distance-measuring instruments (DMIs), computerized and video license plate matching, cellular phone tracking, automatic vehicle identification (AVI), automatic vehicle location (AVL), and video imaging. The various advanced techniques are described, the necessary equipment and procedures are outlined, the applications of each technique are discussed, and the advantages and disadvantages are summarized. Electronic DMIs are low in cost but typically limited to congestion monitoring applications. Computerized and video license plate matching are more expensive and would be most applicable for congestion measurement and monitoring. Cellular phone tracking, AVI, and AVL systems may require a significant investment in communications infrastructure, but they can provide real-time information. Video imaging is still in testing stages, with some uncertainty about costs and accuracy.
Nonresponse and Urban Travel Models
Authors: Thakuriah Piyushimita (Vonu) , Sen Ashish , Sööt Siim , Christopher Ed J.
Published: August 2018

Considerable attention has been paid to the presence of nonresponse in large-scale travel surveys on the basis of which urban travel demand models are developed. It has been shown that the effect of nonresponse can be reduced by careful model building, with categorical trip generation models as an example. The same philosophy is extended to logit mode split models and exponential gravity models to show that the usual levels of nonresponse that one encounters in urban travel surveys have virtually no adverse effects on the parameter estimates of these models if the model has been specified correctly. Some simulation results are also presented to show the behavior of logit and exponential gravity model parameter estimates under conditions on nonresponse.
SMASH (Simulation Model of Activity Scheduling Heuristics): Some Simulations
Authors: Ettema Dick , Borgers Aloys , Timmermans Harry
Published: August 2018

Travel decision making is increasingly regarded as a highly complex process in which individuals not only decide about frequency of trips, travel modes, and routes, but also about activity participation and sequencing and timing and duration of activities and trips. This raises the question of whether or not traditional discrete-choice models still provide the best starting point for realistically modeling such a process. Some scholars consider computational process models (CPMs) a promising approach because they allow for heuristic search and suboptimal reasoning processes, which are typical for complex decision making. A model of activity scheduling, SMASH (Simulation Model of Activity Scheduling Heuristics), which incorporates aspects of discrete-choice modeling and CPMs, has been proposed. The model describes the pretrip planning phase, in which individuals decide which activities to perform, at what locations, at what times, in which sequence, and how to travel to the various activity sites. The calibration of this model, using data collected with the interactive computerized procedure MAGIC, has been described in the literature. The results indicated that when scheduling their activities, subjects seem to trade off attributes of activities (time constraints, duration), attributes of the schedule (time spent on activities, overall travel time, realism) and characteristics of the scheduling process (amount of effort already involved in the scheduling process) to obtain feasible schedules. More extensive tests, using simulation experiments, of the model's internal, predictive, and face validity are described. SMASH was used to predict subjects' activity schedules based on their activity agenda and information about their spatio-temporal circumstances. The predicted schedules were then compared with the activity schedules conceived by the subjects themselves under different circumstances, to assess the model's validity. The tests indicated that the model provided satisfactory results with respect to the reproduction of the observed activity schedules. The results of the validity test warrant the use of the model for assessing the effects of various policy measures such as time policies, land use policies, and travel demand management.
Access Management Using Geographic Information Systems and Traffic Management Tools in Pennsylvania
Authors: Chung Jin-Hyuk , Goulias Konstadinos G.
Published: August 2018

A new method for access management using traffic impact tools is described. The method targets impact assessment of developments combined with large activity centers. The magnitude of impact of large developments necessitates assessment of their regional and local effects on transportation networks. The method described combines regional and local traffic models and uses geographic information systems (GISs) as support tools. It was created as an access control method for computerized models and addresses supply-side transportation improvements (e.g., number of lanes, signalization, and parking controls) and their effect on traffic flow in an attempt to create better quantitative models for congestion management and access control by considering local and regional traffic impacts together. GIS technology enables users to create detailed highway networks for use in regional forecasting models and in smaller traffic simulation models. The data, models, and software used are outlined and an example of application is provided. The initial results show the efficacy of the concept and the resulting models. In the regional model, the new development generates not only new traffic volume on the network, but also route-choice changes influenced by the level of service on the specific corridors in the study area. Another component of the new model is a local model connected to a regional model through interface software. Using Traf-NETSIM, two scenarios were simulated to test the efficacy of this model system. Twenty-four independent simulation runs indicated that the access control scenario results in higher speed and less traffic delay on the primary arterial road.
Geographic Information System Framework for Modeling Mobile-Source Emissions
Authors: Bachman William , Sarasua Wayne , Guensler Randall
Published: August 2018

Because vehicle activities and the emissions associated with them can be correlated with specific points in time and space, the modeling capabilities of a geographic information system (GIS) are well suited to the modeling of mobile-source emissions. A GIS-based modeling approach can provide emissions estimates for both on-network and off-network vehicle activities on a modal basis (as a function of various vehicle operating modes that significantly affect vehicle emission rates). An entire metropolitan region can be modeled on a zone, link, and point basis. Vehicle subfleet composition can be tracked or estimated and combined with estimates of vehicle activity and characteristic operating modes to provide emissions estimates in a spatial and temporal context. Emissions from various modal activities are aggregated into grid cells to be used as input to an airshed model. Identifying spatial and temporal distributions of these activities adds to a greater understanding of emissions impacts. A research prototype of this modeling concept was produced to illustrate its capabilities and identify difficulties that must be addressed in the development of a fully functional model. The GIS-based displays and hard-copy maps that present the spatial variability of emissions levels help improve the communication of research findings to decision makers and the public. The effort being undertaken at Georgia Institute of Technology in conjunction with the Environmental Protection Agency to develop a next-generation modal emissions model within a GIS framework is described.
Distributed Approach to Real-Time Control of Complex Signalized Networks
Authors: Yagar Sam , Dion François
Published: August 2018

Urban traffic characteristics are examined along with the various available current approaches to controlling traffic efficiently at signalized intersections. Fixed-time, central, and distributed real-time control approaches are considered. It is determined that the best method of control varies with network and flow conditions. It is concluded that for smooth traffic and uncomplicated networks that provide good opportunity for progression, a centralized quasi-real-time model such as the split, cycle, and offset optimization technique (SCOOT) is appropriate. However, when faced with significant demand fluctuations or interference from transit or emergency vehicles, a distributed real-time model will be required. The paper recommends use of a fully distributed model to deal with such conditions, at least for the foreseeable future until appropriate hierarchical models can be developed.
Combined Model for Signal Control and Route Choice in Urban Traffic Networks
Authors: Gartner Nathan H. , Al-Malik Mohammed
Published: August 2018

Traffic signals have a significant effect on the choice of routes by motorists in urban areas. They are of primary importance in the development of advanced traffic management strategies that involve dynamic rerouting of traffic flows through signal-controlled street networks. A combined network model that simultaneously accounts for both the route choices made by motorists and the desired signal controls to match these choices is presented. Given origin-destination travel demand information, the model generates signal controls to optimize network performance and calculates the resulting traffic volumes in the network. This optimization model inherently reflects the mutual consistency between traffic flows and signal controls. The model is applicable to both fixed-time and demand-responsive signals. Computational procedures and sample network solutions are presented.
Multivariate Optimization Strategies for Real-Time Traffic Control Signals
Authors: Memon Ghulam Q. , Bullen A.G. R.
Published: August 2018

The application of modern heuristic techniques, neural networks, simulated annealing, tabu search, and genetic algorithms for multivariate optimization is receiving increased attention compared with traditional techniques like hill climbing and gradient search. In the present research the efficiency and effectiveness of genetic algorithms are investigated for their application to the real-time optimization of traffic control signal timings and are compared with the efficiency and effectiveness of the Quasi-Newton gradient search method. The development, testing, comparison, and evaluation of these two multivariate optimization techniques for inclusion in the real-time traffic adaptive control system LOCAL model developed at the University of Pittsburgh as a part of an FHWA contract to a consortium led by the University of Maryland are described. The measures of effectiveness used in the comparisons include optimum total stopped delay, percentage of improvement in total stopped delay, optimal phase timings, execution time, and code size. Testing and evaluation results indicate that genetic algorithms are more efficient and effective than the Quasi-Newton method for this real-time application.
Estimating Impact of Signal Hardware Improvements
Authors: Skabardonis Alexander
Published: August 2018

Signal equipment upgrades (e.g., multiple timing plan capability and signal interconnection) are commonly used to improve the quality of traffic flow in urban arterials and networks. The findings of the assessment of the effects of alternative control scenarios to assist practicing engineers in conducting analyses to determine the effectiveness of proposed signal equipment upgrades are presented. The effectiveness of hardware improvements was evaluated against the optimal timings with the available equipment to differentiate the benefits from installing hardware from the benefits from signal timing optimization. Alternative signal operations strategies were simulated through the NETSIM model on eight real-world test networks. Field data on traffic performance were collected before and after the installation of improved hardware in three demonstration projects. The analysis of the results quantified the effects of design and traffic characteristics on the expected benefits from hardware improvements. Comparison with field results from several hardware projects in California indicates that the study procedures and recommendations provide reasonable estimates of the improvements likely to be achieved from signal control upgrades.
Guidelines for Actuated Controllers in Coordinated Systems
Authors: Chang Edmond Chin-Ping
Published: August 2018

Research sponsored by the Texas Department of Transportation, Efficient Utilization of Actuated Controllers in Coordinated Traffic Control Systems, was used to develop a set of reliable control strategies to allow users to improve the overall design and operation of actuated controllers in conventional coordinated systems. The recommended analysis procedure can help users generate the signal timing parameters for coordinated arterial or network operations. Actuated, coordinated traffic signal system implementation will maximize the available resources for effective coordinated operations during undersaturated conditions, demand variations, and near-saturation conditions. The recommended coordination strategies and implementation guidelines for using actuated controllers effectively on coordinated signal systems are summarized. The study will effectively assist users in selecting the proper controller-detector combinations and improving system detector locations. It will also aid users in optimizing actuated timing parameters in actuated control operation of arterial signal systems.
Predicting High-Occupancy-Vehicle Facility Demand
Authors: Alexiadis Vassilios , Rhoades Krista , Dowling Richard , Billheimer John , May Adolf D.
Published: August 2018

The results of the methodology development effort for FHWA project Predicting the Demand for High-Occupancy-Vehicle (HOV) Lanes are presented. This research project is a 2-year effort to develop a methodology and microcomputer software model for quickly analyzing HOV lane demand and operations. The methodology provides a set of quick-response procedures for predicting and evaluating the impact of HOV lanes on person demand, vehicle demand, automobile occupancy, congestion, delay, air quality, and fuel consumption.
Evaluation of High-Occupancy-Vehicle Lanes on Long Island Expressway
Authors: Ugolik Wayne , O'Connell Nancy , Gluck Jerome S. , Sookram Atma
Published: August 2018

New York State's first suburban high-occupancy-vehicle (HOV) lanes were opened in May 1994 along a 19.3-km (12-mi) stretch of the Long Island Expressway (LIE), I-495 in western Suffolk County, a major suburb of metropolitan New York City. As with some other HOV facilities across the country, the implementation of HOV lanes on Long Island remains controversial. Nevertheless, HOV lanes continue to have an important role in subsequent plans to manage congestion on the LIE. In May 1991 the New York State Department of Transportation formed the LIE/HOV task force to provide advisory opinions on key HOV issues. The task force, comprising private-sector and government representatives, recommended among its numerous findings that the New York State Department of Transportation establish a comprehensive HOV monitoring program to provide up-to-date information to the media and concerned citizens, as well as help fine-tune operational and marketing elements associated with HOV lane usage and to provide firsthand information and guidance for the subsequent development of HOV lanes on the LIE and in the region. The department, in conjunction with consultant services, instituted a monitoring program that involved surveys and focus groups and periodic compilation of relevant HOV data. The first stage of that ongoing evaluation process is reported. A finding of note is that the HOV lanes have encouraged new ridesharing. Also, both HOV users and nonusers support extending the HOV lanes on the LIE.
Effect on Congestion and Motorcycle Safety of Motorcycle Travel on High-Occupancy-Vehicle Facilities in Virginia
Authors: Jernigan Jack D. , Lynn Cheryl W.
Published: August 2018

The Intermodal Surface Transportation Efficiency Act of 1991 mandated that motorcycles be permitted to travel on federally funded high-occupancy-vehicle (HOV) facilities unless they created a safety hazard or adversely affected HOV operations. Although motorcycles had previously been banned from traveling on Virginia's HOV lanes, the Commonwealth Transportation Board (CTB) authorized motorcycle travel on HOV facilities in Virginia as of September 21, 1992, for a 2-year trial period. Study of that 2-year trial period found that motorcycles account for as much as 3 percent of the annual peak traffic volume on some HOV lanes. However, in the 2 years after the CTB authorized their travel on HOV facilities, there were only five motorcycle crashes on HOV lanes in the peak direction during hours that HOV restrictions were in effect. The study concludes that there is no evidence that allowing motorcycles to travel on HOV lanes in Virginia has an adverse impact on motorcycle safety or congestion on HOV lanes.
Development of Arterial High-Occupancy-Vehicle Lane Enforcement Techniques
Authors: Stoddard Angela M.
Published: August 2018

The objective of this study was to develop effective enforcement techniques for arterial high-occupancy-vehicle (HOV) lanes. To accomplish this objective, enforcement techniques that have been studied for freeway HOV lanes were identified, arterial HOV lanes were classified, and cities with arterial HOV lanes were contacted to determine the experience with arterial HOV lane enforcement. During the first few weeks of operation, enforcement officers should be conspicuous on the facility, stopping violators and informing them about HOV lanes. No tickets should be issued during the first few weeks of operation. This procedure would allow violators to learn about HOV lanes without being penalized. The enforcement location should be in areas with few right turns, to minimize the number of vehicles legally turning right in the HOV lane. The violators should be stopped in an adjacent driveway or parking lot; therefore, the HOV facility can continue to operate. The recommended enforcement technique depends on the vehicle types that are allowed in the HOV lanes. For facilities with bus-restrictions only, the violation is the type of vehicle rather than the vehicle occupancy. It is recommended that video cameras be used to enforce arterial HOV lanes restricted to buses only. Video cameras can effectively determine the types of vehicles on the arterial HOV lane and can also be used for surveillance. On facilities restricted to buses and carpools, it is recommended that enforcement officers monitor vehicle occupancy. With the current technology limitations, enforcement officers can most accurately determine vehicle occupancy.
Multiple-Interval Freeway Traffic Flow Forecasting
Authors: Smith Brian L. , Demetsky Michael J.
Published: August 2018

Freeway traffic flow forecasting will play an important role in intelligent transportation systems. The TRB Committee on Freeway Operations has included freeway flow forecasting in its 1995 research program. Much of the past research in traffic flow forecasting has addressed short-term, single-interval predictions. Such limited forecasting models will not support the development of the longer-term operational strategies needed for such events as hazardous material incidents. A multiple-interval freeway traffic flow forecasting model has been developed that predicts traffic volumes in 15-min intervals for several hours into the future. The nonparametric regression modeling technique was chosen for the multiple-interval freeway traffic flow forecasting problem. The technique possesses a number of attractive qualities for traffic forecasting. It is intuitive and uses a data base of past conditions to generate forecasts. It can also be implemented as a generic algorithm and is easily calibrated at field locations, suiting it for wide-scale deployment. The model was applied at two sites on the Capital Beltway monitored by the Northern Virginia Traffic Management System. The nonparametric regression forecasting model produced accurate short- and long-term volume estimates at both sites.
New Methodology for Smoothing Freeway Loop Detector Data: Introduction to Digital Filtering
Authors: Coifman Benjamin A.
Published: August 2018

A new methodology has been developed for smoothing loop detector data based on digital signal processing. After introducing basic signal processing theory, existing smoothing techniques like fixed-time averages, cumulative sums, and moving-time averages—all subsets of the larger digital signal processing methodology—are described. Nontraditional smoothing techniques based on custom digital filter design are then presented, specifically, low-pass filters that “pass” slowly changing features of the detector data unchanged while attenuating rapidly changing features. Custom digital filter design gives more control over the smoothing process than do traditional smoothing methods. In particular, the amount of amplification or attenuation at a given frequency (e.g., rapidly or slowly changing features) can be set. Whether a custom filter or a traditional smoothing process is used, an understanding of the frequency response can increase the usefulness of the resulting data by clarifying the limitations of the given smoothing process. To illustrate this, several smoothing processes are presented and contrasted using the same data set. The use of a custom digital filter is demonstrated in three practical applications: an examination of the bivariate flow-occupancy relationship and use of the filtering process to eliminate unstable disturbances from the data set, speed estimation from a single detector under congested conditions, and temporal issues relating to shock wave and fluctuation propagation specifically.
Evaluation of Compliance Rates and Travel Time Calculation for Automatic Alternative Route Guidance Systems on Freeways
Authors: Kühne Reinhart D. , Langbein-Euchner Karin , Hilliges Martin , Koch Norbert
Published: August 2018

This study outlines the concept of extending an available simulation model for evaluation of freeway route guidance systems using the compliance rates of drivers with alternative route recommendations based on measurements from the freeway subnetwork near Munich, Germany. The system works with variable direction signs that automatically display routing instructions to prevent congestion on the main road. The effectiveness of the system is assessed by calculating the travel times with and without an alternative route guidance system in operation. The result is a decrease in individual travel times on the main road and overall travel time savings for all traffic participants of the system. The simulation indicates a high sensitivity of diverting portions of traffic that allows an exact validation. The diverted traffic affects not only travel time and the congested area but also the destinations, which permits the use of the compliance rate as an accurate fit parameter for exact description of traffic patterns from measurement data.
Transferability of Freeway Incident Detection Algorithms
Authors: Stephanedes Yorgos J. , Hourdakis John
Published: August 2018

This research seeks to evaluate the potential for transferability of new freeway incident detection algorithms that can be used in automatic incident detection. An incident detection logic is evaluated that distinguishes incidents from recurrent congestion and other traffic disturbances using exponential smoothing. The algorithm is tested with loop detector data from test sites on I-35W in Minnesota and I-880 in California with promising results. Test results indicate that, at the Minnesota test site, algorithm performance improves over earlier findings with a limited data set, without requiring recalibration. At a detection rate of approximately 60 percent, the algorithm produces one false alarm per hour in the total (southbound and northbound) 40-km (25-mi) test section, which includes 54 detector stations. When the algorithm is recalibrated and tested at the California site, its performance further improves. The performance of the algorithm is compared with that of major algorithms of comparative type and is found to be superior at all times. This superiority is not affected by the transport of the algorithm across sites; it is still observed in analyzing northbound and southbound, peak and off-peak, and accident versus nonaccident detection. The findings indicate a strong transferability potential of the new algorithm.
Deriving Incident Management Measures Using Incident Probability Models and Simulation
Authors: Wilmink I. R. , Immers L. H.
Published: August 2018

Incidents cause a large part of congestion and subsequent costs. Incident management is aimed at preventing the occurrence of incidents as well as minimizing the impact of incidents that occur. Two elements of incident management are addressed: the modeling of the incident occurrence probability for freeway sections and the modeling of the logistics of incident removal by various emergency services (tow trucks, ambulances, etc.). Models are presented that relate incident probabilities to road and traffic variables such as number of lanes, type of section (e.g., weaving sections), and traffic volumes and composition. These models give insight into the factors determining incident frequencies and may be used to design incident prevention measures. The results indicate that, for example, the splitting up of weaving sections into a series of joins and forks may be a very effective way to reduce the number of incidents. Traffic characteristics and the number of lanes also play important roles. These incident probability models can be used to generate the input for a logistics model. Such a model is presented. It was developed to test the effectiveness of various procedures aimed at minimizing incident duration. Examples of such procedures are the optimal location of emergency and recovery vehicles, given the spatial pattern of incident occurrence; optimal assignment of such vehicles to incidents; and various strategies for going from the vehicle's station to the incident site. These strategies include the permission to use the shoulder lane for emergency services. Experiments with the models for a heavily trafficked part of the Dutch freeway network indicate that a combination of such strategies can reduce incident congestion costs by nearly one-half.
I-880 Field Experiment: Data-Base Development and Incident Delay Estimation Procedures
Authors: Skabardonis Alexander , Petty Karl , Noeimi Hisham , Rydzewski Daniel , Varaiya Pravin P.
Published: August 2018

The collection and processing of field data on freeway incidents and operating conditions are described, and the development and application of a methodology for estimating incident delays are presented. The data were collected on a section of the I-880 freeway in the San Francisco Bay Area before and after the implementation of freeway service patrols (FSPs). Incident characteristics were obtained through observations of probe vehicle drivers traveling at an average of 7-min headways. Travel times were obtained from the specially instrumented probe vehicles. Speeds, flows, and occupancies at 1-sec intervals were collected from closely spaced loop detectors on the freeway main line and the ramps. Software was developed to process the data and create a computerized data base. The I-880 data base consists of 276 hours of field data that are uniquely linked to provide a complete representation of the freeway operating conditions at the test site. Improved procedures for estimating incident delay and other performance measures were developed and incorporated into the data processing and analysis software. The delay estimation methodology and field data were used to determine the benefits of the FSPs. The results indicate that the FSP is a cost-effective incident management measure at the study section.
Decision-Making System for Freeway Incident Response Using Sequential Hypothesis Testing Methods
Authors: Madanat Samer M. , Cassidy Michael J. , Teng Hua-Liang , Liu Pen-Chi
Published: August 2018

Recent research in advanced traffic management systems has emphasized incident detection and response to mitigate nonrecurring congestion. Existing incident response decision-making algorithms do not account for the expected losses associated with false alarms, undetected incidents, and delayed incident response. A freeway incident response decision-making system based on sequential hypothesis testing techniques is presented. The primary feature of this decision-making system is that it minimizes the sum of the expected losses associated with false response, nonresponse, and delayed responses to incidents through a dynamic programming algorithm. The results of simulation tests indicate that this algorithm performs better than typical Bayesian incident response algorithms for mean response time, false response rate, and nonresponse rate.
Assigning Traffic over Essentially-Least-Cost Paths
Authors: Hunt David T. , Kornhauser Alain L.
Published: August 2018

The concept of a least-cost path is generalized. The simplest of all traffic assignment models assumes that all trip makers from a single origin-destination (O-D) pair take a single path, for example, the minimum cost path or the equilibrium path. However, in many applications, it is observed that trips from a single O-D do not all take the same path. It is not difficult to imagine commuters from a large residential area using different routes to travel to a common workplace simply because each has a different disutility function. In reality no two routes have exactly the same cost; however, when modeled deterministically as network graphs, these graphs invariably have O-Ds with degenerate (multiple) shortest paths. The ability to measure the “best” route should also be seriously questioned. Given the level of uncertainty that exists in any link attribute, the variance of the accumulated uncertainty of that attribute over any given route can easily be such as to make many routes statistically indistinguishable from the deterministic best route. An algorithm for generating the set of paths that are essentially indistinguishable from the least-cost path is presented. These paths are constructed from the set of “locally acceptable” detours that are within a given cost threshold. This is different from the classic “k” least-cost path problem in that it operates on a cost threshold as opposed to a predetermined number of paths. Methods are then presented for assigning traffic to this subnetwork of essentially-least-cost paths.
Congestion-Based Peak Spreading Model
Authors: Allen William G. , Schultz Gordon W.
Published: August 2018

Peak-hour models are necessary to model transportation system changes (HOV lanes) and policy measures (peak-hour pricing) that vary by hour. It is evident that the temporal distribution of travelers has changed over the past several years, and this trend will likely continue in the future. Increasing congestion and the growing need for more flexibility in scheduling activities are thought to be the key motivators of this; the greater use of workplace flextime and the expanded operating hours of many businesses permit it to occur. A peak spreading model that accounts for congestion in determining the proportion of a.m. peak period vehicle traffic that will travel during the peak 1 hr is described. This model assumes that the proportion of the day's travel occurring during the a.m. peak 3 hr will remain stable over time. However, the proportion of the peak period's traffic occurring in the peak 1 hr is expected to vary with the level of congestion and trip length. Models were developed by trip purpose that “flatten” the a.m. peak 1 hr as congestion increases and as the trip length increases. This model was calibrated for the Washington, D.C., area on the basis of a 1987–1988 home interview survey and is presently being validated as part of the Dulles Corridor Transportation Study.
Two-Stage Vehicle Availability Model
Authors: Allen William G. , Perincherry Vijay
Published: August 2018

It is well accepted that travel forecasting models benefit from the stratification of travel markets by socioeconomic levels. The number of vehicles available is a key indicator of that level. Using this variable requires that the proportion of households by vehicles available be forecast for each zone. An improved submodel for forecasting vehicle availability by incorporating transit accessibility and land use indicators along with the usual demographic variables is described. This model uses a two-stage approach. The first stage is similar to many other models in current use. In the first step, a lookup table is used to identify an initial estimate of the proportion of 0-vehicle, 1-vehicle, 2-vehicle, and 3+-vehicle households on the basis of the household's size (1–4 +), number of workers (0–3 +), and income quartile (1–4). This lookup table has 52 cells, with each cell containing the four proportions by vehicles available. Census Public Use Microdata Sample data were used to create this lookup table. The second stage applies an incremental logit model to the initial proportions. In this step, the effects of transit accessibility and land use form on vehicle availability are modeled. Accessibility and density measures are used to calculate a “disutility” measure, which is then used to modify the initial percentages. Good transit service and high development density are associated with lower vehicle ownership. Vehicle availability models of this type recently have been successfully calibrated for the Washington, D.C., and Seattle, Washington, areas.
Forecasting Balanced Highway Volumes Using Modeling Packages and Spreadsheets
Authors: Mekky Ali
Published: August 2018

In many applications, particularly upon requests from highway engineering and design departments, transportation planners need to forecast link volumes of a particular highway. That usually includes turning movements at various interchanges and intersections. It is not unusual, for certain links in a high-growth area, that one or more of the forecast volumes are less than the present ones. A probable reason is that some of the base year volumes at that location are underestimated, or, generally, the base year model volumes are not very similar to the base year traffic counts. Attempts by practitioners to “factor up” those low volumes might result in an unbalanced forecast. The question of producing forecasts that are consistent among themselves and compatible with the base year counts using modeling packages and spreadsheet techniques is addressed. The latter is important particularly for transportation planners who do not have packages directly available to them. For planners who have packages, however, spreadsheet techniques could be beneficial when a quick response for several scenarios is needed. Simple techniques using a spreadsheet with or without transportation modeling software are described and applied to an example from the city of Niagara Falls, Canada. The results are compared with a more sophisticated technique. It is argued that the simple techniques can provide good approximations to the more sophisticated one in some applications.
Multivariate Marginal Frequency Analysis of Activity and Travel Patterns in First Four Waves of Puget Sound Transportation Panel
Authors: Ma Jun , Goulias Konstadinos G.
Published: August 2018

An analysis of activity and travel patterns that explicitly accounts for transportation level of service via composite accessibility measures, land use type, and density around residence and workplace of survey participants in the Seattle region is presented. Using the Puget Sound Transportation Panel (PSTP) data, individuals' activity and travel patterns are first grouped into a few relatively homogeneous behavioral groups using cluster analysis. This is done to reduce the great diversity in individuals' behavior into a few representative patterns of behavior using activity and travel indicators simultaneously. Taking the contextual analysis approach, four-level multilevel models that include temporal, spatial, household, and person effects are constructed. The derived accessibility measures of individuals' residence and workplace are then included in the four-level multilevel pattern selection models to study the relationship between individuals' characteristics and their activity and travel pattern choices. The analysis is done by separating employed from unemployed persons and provides evidence that level of service and land use are strong determinants of activity participation and trip making. Their effect, however, depends on the person's employment status.
Household Activities, Life Cycle, and Role Allocation
Authors: Vadarevu Ramana V. , Stopher Peter R.
Published: August 2018

Four basic hypotheses about activities that are fundamental to pursuing an activity-based travel-forecasting modeling procedure are presented. They include classifying activities as mandatory, flexible, or optional; using life-cycle stages to differentiate the amount of time spent on different activities; determining whether there are differences in proportionate amounts of time spent on activities by gender; and examining role allocations to activities between people in a household on the basis of working status and gender. The hypotheses are tested by using a subsample of households from a sample collected in Boston in 1991 from an activity diary. Within the limitations of the data, it is found that the classification of activities appears to be sensible, and statistically significant differences are found among life-cycle groups. Differences are also found by gender and working status. Recommendations are made for further research and on some of the implications of these findings for activity modeling.