bluuebunny/crossref_metadata_2025 huggingface dataset:
Congested Freeway Microsimulation Model Using VISSIM
Authors: Gomes Gabriel , May Adolf , Horowitz Roberto
Published: April 2007

A procedure for constructing and calibrating a detailed model of a freeway by using VISSIM is presented and applied to a 15-mi stretch of I-210 West in Pasadena, California. This test site provides several challenges for microscopic modeling: a high-occupancy vehicle (HOV) lane with an intermittent barrier, a heavy freeway connector, 20 metered on-ramps with and without HOV bypass lanes, and three interacting bottlenecks. Field data used as input to the model were compiled from two separate sources: loop detectors on the on-ramps and main line (PeMS) and a manual survey of on-ramps and off-ramps. Gaps in both sources made it necessary to use a composite data set, constructed from several typical days. FREQ was used as an intermediate tool to generate a set of origin-destination matrices from the assembled boundary flows. The model construction procedure consists of (1) identification of important geometric features, (2) collection and processing of traffic data, (3) analysis of the main-line data to identify recurring bottlenecks, (4) VISSIM coding, and (5) calibration based on observations from Step 3. A qualitative set of goals was established for the calibration. These were met with relatively few modifications to VISSIM's driver behavior parameters.
Performance Evaluation of Microscopic Traffic Flow Models with Test Track Data
Authors: Ranjitkar Prakash , Nakatsuji Takashi , Asano Motoki
Published: April 2007

The performance of six microscopic traffic flow models was investigated on the basis of how well these models fit with the real-time kinematic Global Positioning System (GPS) measurements. Ten passenger cars equipped with the GPS receivers participated in the car-following experiments, conducted at a test track. The genetic algorithm-based approach is adopted to optimize the model parameters for two different cases: using speed and headway data. The optimized performance of each model is analyzed for various driving conditions introduced by the different level of disturbances to the lead vehicle's speed, which include half-wave, one-wave, two-wave, three-wave, random, and constant speed patterns. In the former case with speed data, five models performed well with the average percentile error ranging from 3.87% to 4.71% and standard deviation ranging from 1.09% to 1.64%. In the latter case with headway data, only three models performed well with the average percentile error ranging from 12.04% to 12.91% and standard deviation ranging from 4.53% to 5.13%. All models performed better in the former case than in the latter case. The interpersonal variations are significant compared with the intermodel variations and indicate individual drivers' influence on the car-following phenomena.
Systematic Validation of a Microscopic Traffic Simulation Program
Authors: Zhang Yunlong , Owen Larry E.
Published: April 2007

To achieve high fidelity and high credibility of a microscopic traffic simulation, model validation is of the utmost importance. A systematic validation effort was performed on an advanced microscopic traffic simulation that uses a multiregime simulation (MRS) approach for its car-following and lane-changing logic. The vigorous validation procedure includes animation comparison and quantitative/statistical analysis at both macroscopic and microscopic levels, and is illustrated through case studies. For validation at the macroscopic level, the averages and other statistics of traffic variables are compared, and fundamental relationships of traffic flow parameters are studied. For validation at the microscopic level, the speed change pattern, vehicle trajectory plots, and headway distribution from simulations are compared with those of the real-world system. The importance of the real-world data sets to model validation is emphasized, and animation comparison that provides intuitive appreciation of the model validity is frequently used. The validation and testing not only show the validity of the MRS model but also illustrate a systematic approach that can be used to validate other simulation models.
Implementing Highway Preventive Maintenance: Comparing Challenges, Processes, and Solutions in Three States
Authors: Carroll Deborah A. , Cheng Rita , Eger Robert J. , Grusczynski Lara , Marlowe Justin , Titi Hani H.
Published: April 2007

One of the central challenges facing today's state transportation policymakers is how to incorporate preventive maintenance concepts and strategies into existing asset-management systems. Seven unique challenges to implementing preventive maintenance are identified in the literature and elsewhere, and a discussion covers the ways states have addressed those challenges through various implementation strategies. Then, case studies provide examples of how that incorporation has occurred in the departments of transportation in Michigan, Kansas, and Nebraska. The three case studies are presented in an effort to demonstrate the advantages and disadvantages of these three unique approaches, herein labeled the top-down approach, for Michigan; the bottom-up approach, for Kansas; and the inclusive approach, for Nebraska. In particular, an examination is presented of how preventive maintenance concepts were integrated into the planning, budgeting, and technical needs-assessment for state highways.
Evaluation of Automated Work Zone Information Systems
Authors: Tooley Melissa S. , Gattis J. L. , Janarthanan Rajeshkumar , Duncan Lynette K.
Published: April 2007

Motorists traveling through work zones are faced with both routine and unexpected tasks of driving coupled with additional distractions provided by the work zone. This can create conflicts despite significant applications of work zone traffic-control devices. When one or more through-traffic lanes are closed and traffic volumes exceed the capacity of merge points or of the reduced number of lanes, congestion can lead to the formation of queues, which result in delays and increased potential for crashes. An automated work zone information system (AWIS) may be implemented at a work zone to notify approaching motorists of changing traffic conditions, such as slowdowns or backups. Research was conducted at rural work zones in Arkansas on I-40, where two lanes of traffic in a direction were reduced to one lane. The objectives were to compare the displays of an AWIS with field observations of traffic conditions and to determine at what volume backups were forming. AWIS was compared with field observations for two traffic speeds, 30 and 50 mph. At 30 mph, the speed at which the system was programmed to identify a backup, AWIS concurred with the field observations 92% of the time. For a perceived backup speed of 50 mph, the system indicated a backup about 88% of the time. Backups formed at short-term flow rates as low as 800 to 900 passenger car equivalents per hour, which is lower than the capacities reported in the literature (1,100 to over 2,000 vehicles per hour).
Work Zone Optimization for Two-Lane Highway Maintenance Projects
Authors: Chen Chun-Hung , Schonfeld Paul
Published: April 2007

On two-lane, two-way highways, pavement resurfacing is usually done by closing one lane at a time. Then, vehicles travel in the remaining lane along the work zone, alternating directions within each control cycle. Such a work zone can be analyzed as a one-way traffic-control system in which queuing and delay processes are analogous to those at a two-phase signalized intersection. Efficient scheduling and traffic control through work zones may significantly reduce the total cost. A model is presented for optimizing work plans, including zone lengths, work durations, starting times, pausing times (if any), and control-cycle times, for work zones on two-lane highways. This is done by minimizing total cost, including agency cost (maintenance cost and idling cost) and user cost (user delay cost and accident cost), while taking into account traffic-demand variations over time. Two optimization methods, Powell's and simulated annealing, are adapted for this problem and compared. In numerical tests, the simulated annealing algorithm yields better solutions using less computer time than Powell's method.
Using Low-Cost Infrared Detectors to Monitor Movement of Pedestrians: Initial Findings
Authors: Kerridge Jon , Armitage Alistair , Binnie David , Lei Lucy , Sumpter Neil
Published: April 2007

Monitoring the movement of pedestrians in everyday environments is difficult, especially if accurate data are required. Typically, data pertaining to the origins and destinations of pedestrians as they move around a space can be obtained only by either locating many observers in the area that is under surveillance or analyzing closed-circuit television footage. The former is error prone and perturbs the space being analyzed; the latter is expensive in regard to the technology and time required. Technical advances in low-cost infrared detectors provide an opportunity to observe pedestrian spaces unobtrusively and determine individual pedestrian trajectories automatically. The underpinning detector technology is described, and the way arrays of such detectors can be used to monitor larger spaces is shown. An outline of the algorithm used to create complete trajectories as pedestrians move between detectors is presented. A series of experiments is described: pedestrians were asked to move in a set of defined patterns in a controlled environment. Initial results from these experiments are discussed. It was found that at Fruin Levels of Service A to C, 93% of pedestrian trajectories could be tracked; that count dropped to 79% at Level of Service D.
Developing a Barrier-Free Map by Using Global Positioning System and Cellular Phones with Digital Cameras
Authors: Osada Teppei , Koike Hirotaka , Morimoto Akinori
Published: April 2007

The recent enactment of the transportation barrier-free law in Japan emphasizes the importance of incorporating a barrier-free approach for any new road facility construction and for improvements to existing road facilities in urban areas. The purpose of this study is to develop barrierfree maps for people with various types of disabilities to help public agencies plan a barrier-free transportation system environment. Statistics show that technological progress and the explosive proliferation of cellular phone use in Japan has reached the level of two phones for every three people. In particular, new advanced cellular phones equipped with additional features such as a Global Positioning System (GPS) and digital cameras are gaining in popularity. The focus is on GPS cellular phones with digital cameras as a tool to collect barrier-free information on the streets. The digital photos and location information generated by the GPS are sent to a personal computer by e-mail. The gathered information is then stored in a geographic information system (GIS) database to display hazardous barrier locations with pictures and messages on a map. Actual field surveys were conducted in the central business district of Utsunomiya City using this method, and information was collected about various barriers for people with different types of disabilities. Barrier-free maps for different types of disabilities were then developed using the multilayer feature of GIS. By comparing hazardous locations for each group of disabilities, both common and differential characteristics were found and summarized in the form of a barrier-free map. Such barrier-free maps are expected to be useful to public agencies for providing a barrier-free transportation environment for people with all types of disabilities.
Assessment of Traffic Volume, Based on Travel Time, to Enhance Urban Network Operation
Authors: Yi Ping , Zhen Haiyan , Zhang Yucheng
Published: April 2007

With the rapid advancement of intelligent transportation systems technologies in recent years, an unprecedented opportunity exists for developing countries to develop their transportation system and supporting infrastructure by taking full advantage of the advanced data acquisition and communication technologies available today. This research explored a potential way to assess the level of traffic over the urban network by using travel-time information obtained from the Global Positioning System. The significance of this application is understood: not having to install system detectors midblock on city streets could mean realizing tremendous cost savings and avoiding the disruption to the operation of the complex traffic system that would result from installation and maintenance activities. The feasibility of calibrating a relationship connecting travel time and traffic volume under various roadway and traffic conditions was studied using Monte Carlo simulation and data regression. Reliability analysis was also performed to assess the stability of the volume estimates in anticipation of changes in the model parameters and roadway capacity. Results from the model implementation and reliability analysis have shown that the proposed approach is capable of reliably describing the level of traffic on the roadway network with an error smaller than 5%.
Learning Systems for Predicting Experiential Travel Times in the Presence of Incidents: Insights and Lessons Learned
Authors: Mark Charles D. , Sadek Adel W.
Published: April 2007

Implementation of the intelligent transportation systems program has resulted in a wealth of readily available data describing key transportation system parameters for many of the nation's roadways. However, the development of systems that can process the data to support effective decision making aimed at improving travel conditions has lagged behind the development of monitoring and data recording devices. A study investigated the feasibility of developing an artificial neural network (ANN) model to predict experiential travel time under transient traffic conditions, including accidents, by using readily available data from roadway sensors in real time. Computational experiments were performed to investigate the impact of several factors on the quality of the ANN's predictions: ( a) the time lag of the input data, ( b) the input variables, and ( c) the temporal resolution of the input variables. With the correct input data set and network parameters, the ANNs were able to predict reasonable values for experiential travel time. The study shows that the length of the time lag did not have a statistically significant effect on ANN performance, that speed appears to be the most influential input variable, and that varying the resolution of the input data produced similar errors for both higher and lower resolutions.
Genetically Designed Models for Accurate Imputation of Missing Traffic Counts
Authors: Zhong Ming , Sharma Satish , Lingras Pawan
Published: April 2007

Highway agencies traditionally have used simple methods to estimate missing values in their data sets since traffic data programs were established in the 1930s. A literature review shows that current practices for imputing traffic data are varied and intuitive. No research has been conducted to assess imputation accuracy. Typical traditional imputation methods used by highway agencies were identified in a study and used to estimate missing hourly volumes for sample traffic counts from Alberta, Canada, to examine their accuracy. It was found that such models usually resulted in large imputation errors. For example, for imputing missing data of a traffic count located on a commuter site, the 95th percentile errors for the traditional methods are usually between 10% and 20%. Advanced models based on genetic algorithms, a time-delay neural network, and locally weighted regression developed in the study show higher accuracy than traditional imputation models. Most of the 95th percentile errors for genetically designed neural network models tested on the same count are below 6%. For genetically designed regression models, the 95th percentile errors are less than 2%. Study results based on the sample traffic counts from different trip pattern groups and functional classes show that underlying traffic patterns have some influence on imputation accuracy. However, genetically designed regression models still can limit the 95th percentile errors to less than 5% in most cases. It is believed that such accurate imputations should be able to supply satisfactory data for decision making at both planning and operation levels.
Double-Sided Determination of Aggregation Level for Intelligent Transportation System Data
Authors: Qiao Fengxiang , Yu Lei , Wang Xin
Published: April 2007

Intelligent transportation system (ITS) data, which are normally collected at a 15- to 30-s interval, are a rich and valuable resource for a variety of applications, including transportation planning. However, raw ITS data exhibit a wide range of fluctuations, which may not be directly useful for planning purposes, for which aggregations taken over longer time intervals are commonly needed. Proper determination of aggregation level of ITS data will ensure the retention of necessary information and the elimination of as much unnecessary information as possible. The traditional approaches to determining aggregation level are intuitive and easy to implement, yet they may be unable to determine whether particular information is kept or lost. The newly developed wavelet-based approach, although good for decomposing original data sets, needs to be further improved. A double-sided technique was developed that could refine the selection of aggregation levels based on two self-defined indices: the dissimilarity index and the information loss index. A computer program coded in MATLAB with the use of the Wavelet Toolbox was developed to implement the proposed technique. A case study illustrating the process was conducted by using real-time ITS data from traffic management centers in the San Antonio TransGuide. It is expected that the proposed technique will maximize the use of real-time ITS data and improve data needs in the urban transportation planning process.
Running Out of and Into Oil: Analyzing Global Oil Depletion and Transition Through 2050
Authors: Greene David L. , Hopson Janet L. , Li Jia
Published: April 2007

A risk analysis is presented of the peaking of world conventional oil production and the likely transition to unconventional oil resources such as oil sands, heavy oil, and shale oil. Estimates of world oil resources by the U.S. Geological Survey (USGS) and C. J. Campbell provide alternative views of ultimate world oil resources. A global energy scenario created by the International Institute of Applied Systems Analysis and the World Energy Council provides the context for the risk analysis. A model of oil resource depletion and expansion for 12 world regions is combined with a market equilibrium model of conventional and unconventional oil supply and demand. The model does not use Hubbert curves. Key variables such as the quantity of undiscovered oil and rates of technological progress are treated as probability distributions, rather than constants. Analyses based on the USGS resource assessment indicate that conventional oil production outside the Middle East is likely to peak sometime between 2010 and 2030. Even if oil production does not peak before 2020, output of conventional oil is likely to increase at a substantially slower rate after that date. Analysis based on data produced by Campbell indicates that the peak of non-Middle East production will occur before 2010. Once world conventional oil production peaks, oil sands and heavy oil from Canada, Venezuela, and Russia and, later, shale oil from the United States must expand rapidly if total world consumption of petroleum fuels is to continue to increase.
Survey of Screening Procedures for Project-Level Conformity Analyses
Authors: Houk Jeffrey , Claggett Michael
Published: April 2007

The transportation conformity rule establishes project-level analysis requirements that apply in carbon monoxide (CO) nonattainment and maintenance areas. These include a requirement for quantitative CO hotspot modeling at all locations affected by a proposed project operating or expected to operate at a Level of Service D or worse. Transportation agencies, aware of declining ambient CO levels and lower idle emission factors in MOBILE6, are concerned that this is no longer an efficient use of their limited resources. A summary is provided of project-level screening procedures developed and adopted by transportation agencies throughout the nation, several innovative practices are highlighted, and recommendations for developing refined screening protocols are offered.
Geometric Models to Calculate Intersection Sight Distance for Unprotected Left-Turn Traffic
Authors: Yan Xuedong , Radwan Essam
Published: April 2007

At signalized intersections with opposing left-turn lanes, inadequate sight distance of left-turn drivers caused by obstructions from opposing left-turn vehicles can not only contribute to a serious safety problem due to drivers misjudging the gaps in the opposing through traffic but also cause increased intersection delay. This delay is created because drivers need more time to make sure that the opposing through lanes are clear. The 2001 AASHTO manual pointed out that the typical poor visibility of opposing through traffic usually occurs at signal intersections with medians wider than 18 ft and recommended two improvement methods: creating parallel offset left-turn lanes and tapered offset left-turn lanes. However, AASHTO did not provide the specific design guideline, nor did it present the related geometric design model. Sight-distance geometric models for unprotected left-turning vehicles from the major road onto the minor road at signalized intersections and vision improvement effects of the two offset methods were developed, and the relationship between available sight distance and related intersection geometric parameters was analyzed.
Fuzzy Model for Safety Evaluation Process of New and Old Roads
Authors: Cafiso Salvatore , Lamm Ruediger , La Cava Grazia
Published: April 2007

More than 50% of traffic fatalities occur on two-lane rural roads, and more than half of these fatalities occur on curved roadway sections. A large body of research can be used to analyze and evaluate the fundamental relationships between accident situation, highway geometric design, driving behavior, and driving dynamics. These factors form the basis for the development of three quantitative safety criteria used to evaluate the hazards of two-lane rural roads with respect to new designs; redesigns; restoration, rehabilitation, or resurfacing projects; and existing alignments. The safety criteria support the design engineer in classifying new or old roadway sections according to good (sound), fair (tolerable), and poor (dangerous) design practices. On the basis of observation of the actual variation in the accident rate with respect to road alignment, a fuzzy model was developed to classify roadway elements by using these safety criteria to obtain a more careful evaluation of highway design inconsistencies. For each criterion, the inconsistencies were included in three fuzzy sets (good, fair, poor) with differing degrees of membership. By defining linear membership functions, it was possible to obtain good results to classify road sections and then to determine a prioritization scale of maintenance interventions. The procedure can be applied to large databases of road networks to identify the more dangerous design elements that need interventions to improve highway safety and to allocate resources under limited budget conditions.
Vehicle Routing and Scheduling Problem with Time Windows and Stochastic Demand
Authors: Chang Mei-Shiang , Lin Yi-Chen , Hsueh Che-Fu
Published: April 2007

A real-world vehicle routing and scheduling problem in which a set of known customers is served by a number of vehicles with known capacity is considered. The demand for each customer is stochastic and needs to be served within a given time window. Strict adherence to the time window constraints for customers who practice the just-in-time concept of inventory management is requisite. One or several factors of vehicle routing and scheduling problems are stochastic. This has a major impact on how the problem is both formulated and solved. A three-index model that is a mixed-integer stochastic program with recourse is proposed. A metaheuristic algorithm for solving this problem is developed. Computation of the objective function of this model is computationally expensive. The proxies to evaluate the moves in tabu search are embedded in this heuristic algorithm. The heuristic was tested with Solomon's 100-customer Euclidean vehicle routing problems with time windows but with the customer demands and vehicle capacity excluded. The test results revealed that problem difficulty was relevant not only to the number of customers but also to the average filling coefficients. A routing schedule with a lower value of the average filling coefficient is made to serve a scattering flock of customers.
Applying a Network Programming Algorithm to a Networkwide Traffic Control Scheme: Simulation-Based Performance Studies
Authors: Wey Wann-Ming , Jayakrishnan R.
Published: April 2007

A complete optimal formulation of a network traffic control scheme in the form of arc flows in a time-expanded network is presented. The platoon dispersion model used in the proposed optimal control formulation forms linear constraints. The integer-linear network programming formulation is solved by using a modified network simplex and branch-and-bound scheme. The formulation does not assume fixed cycle lengths or phase sequences. It assumes full information on external inputs, but it can be incorporated into a sensor-based environment, as well as into a feedback control framework. The integer-linear program formulation may not be efficiently solved by standard simplex and branch-and-bound techniques. Network programming formulations that can be used to handle the linear equations and the integer constraints at the intersections are discussed. A special-purpose network simplex algorithm for fast solution is also mentioned. The optimization model takes the form of mixed integer-linear programming. The control strategies generated by these optimization models were compared with those derived from conventional signal timing models by using the TRAF-NETSIM microscopic simulation model. The proposed optimization models consistently outperformed the conventional signal control methods with respect to the system delay objective. It was found that the optimization models successfully produced optimal signal timing plans for the various signalized intersections, including simulated and real-world networks.
Enhanced Dynamic Origin-Destination Matrix Updating with Long-Term Flow Information
Authors: Stathopoulos Antony , Tsekeris Theodore
Published: April 2007

The problem of updating dynamic origin-destination (O-D) matrices by exploiting a long-term time series of link traffic counts in large-scale transportation networks without the need for surveys or census data is investigated. Different time-recursive mechanisms for analysis of these data to enhance the performance of the models currently used to synthesize within-day dynamic O-D matrices are suggested. The efficiency of the proposed procedure is investigated with respect to different formulations and related solution algorithms (based on entropy maximization and generalized least-squares). The impacts of different assumptions on model performance are also examined. These include the length of the time scale in which the flow information is updated and the selection of the weekday for which the flow information is collected. The results of the statistical analysis and the model performance measures demonstrate that the proposed time-recursive procedure for an information updating period of 2 years can produce an improved prior O-D matrix that may significantly enhance the subsequent updating of dynamic O-D matrices corresponding to a series of days of the week.
Integrated Approach for Emergency Medical Service Location and Assignment Problem
Authors: Yang Saini , Hamedi Masoud , Haghani Ali
Published: April 2007

In an emergency medical service (EMS) system, the depot location and fleet assignment greatly affect the average response time, which is the main criterion for measuring system performance. Whereas the EMS depot location problem is a strategic problem, the fleet assignment problem is a tactical one. As such, the EMS depot location and fleet assignment problems are usually solved separately under some simplified assumptions. However, there is a potential for savings in both the average response times and the capital and operating costs if these problems can be solved simultaneously. A simulation model for EMS vehicle dispatching was developed. This model is calibrated with real-world data, and it is incorporated in a genetic algorithm to help solve the EMS depot location and fleet assignment problems simultaneously. Emergency types, their response priorities, and whether or not they require dispatching of multiple units are taken into consideration in the model. The average response time and the capital and operating costs are used as criteria for evaluation.
Analysis of Traffic Flow Characteristics on Signalized Arterials
Authors: Gartner Nathan H. , Wagner Peter
Published: April 2007

The characteristics of traffic flows on signalized arterials are examined within a cellular automaton microsimulation model. The model is used to analyze arterial throughput and travel times for given densities, coordination schemes, and signal spacings. A fundamental three-dimensional relationship is established between flow, density, and offsets for signalized arterials. In particular, it is shown that arterial throughput is dependent on offsets and that the constituent single-intersection limiting capacity, as determined by the saturation flow and the green splits, can be realized only under optimal coordination conditions for a limited range of densities on the arterial. This finding is a manifestation of the important role that signal coordination and, in fact, intelligent transportation systems in general play in the operation of urban street networks.
Methodology for Estimating Operating Speed and Capacity in Work Zones
Authors: Benekohal Rahim F. , Kaja-Mohideen Ahmed-Zameem , Chitturi Madhav V.
Published: April 2007

A new step-by-step methodology for estimation of operating speed and capacity in work zones on highways is presented and validated. The underlying principle of this methodology is that the operating factors in work zones, which include work intensity, lane width, lateral clearance, and other factors, cause motorists to reduce their speed. The reduced speed adversely affects the capacity of the work zones. Video data were collected for around 30 h from 11 work zones on Interstate highways in Illinois where one of the two lanes was closed. These work zones included eight long-term and three short-term ones. Work intensity in the work zone was quantified, and the relationship between work intensity and consequent speed reduction in construction zones was established. Speed reduction in a long-term work zone was established with field data, and the reduction in a short-term work zone was established with data from a driver survey. These relationships were used to compute the operating speed in the work zone. A speed-flow curve, which represents the operating conditions in work zones, was developed. The congested part of the curve was developed with the field data, corresponding to platooning vehicles, and the uncongested part was developed from information in the Highway Capacity Manual and the educated judgment of the authors. Once the operating speed is known, this curve can be used to obtain the capacity of the work zone. The developed methodology was used to predict the operating speed and capacity of work zones, and these predictions were compared with field data for validation.
Freeway Users' Perceptions of Quality of Service: Comparison of Three Groups
Authors: Hostovsky Charles , Wakefield Sarah , Hall Fred L.
Published: April 2007

Focus group sessions were held with rural freeway commuters who use Highway 403 from Brantford to Hamilton, Canada, to identify the characteristics of their trip that helped determine their view of the quality of service for the trip. The results from that analysis were then compared with two other types of freeway users who had previously been studied: urban freeway commuters who use Queen Elizabeth Way from Toronto to Hamilton and tractor-trailer drivers. The findings suggest that despite some commonality among the three groups, each group valued a trip characteristic that they did not experience or at least could not be sure of. That characteristic differs across the three groups. Urban commuters were concerned about travel time, rural commuters about maneuverability, and truck drivers about steady traffic flow and physical road conditions. Despite these differences, an argument can be made that density, the service measure for freeways, is a reasonable proxy for most of these concerns. The results also suggest that it is harder to defend by using the same breakpoints on density for different types of freeways or even for different types of drivers. Although operational issues were the primary concern, it may also be appropriate to consider a second rating that addresses the quality of the facility as well as the existing level-of-service method that addresses the quality of operations on it.
Normal Acceleration Behavior of Passenger Vehicles Starting from Rest at All-Way Stop-Controlled Intersections
Authors: Wang Jun , Dixon Karen K. , Li Hainan , Ogle Jennifer
Published: April 2007

Acceleration characteristics of passenger cars starting from rest are often used in traffic simulation, modeling of vehicle fuel consumption and emissions, and design of intersections, acceleration lanes for entrance terminals, turning bays, and passing lanes. Most of the previous studies developed four different acceleration models: the constant acceleration model, the two-phase model, the linear-decreasing acceleration model, and the polynomial acceleration model. However, most of the studies were based on outdated and limited data, so their conclusions may not be applicable for the current vehicle fleet and drivers. The normal acceleration behavior of current passenger vehicles starting from rest at all-way stop-controlled intersections is evaluated, and the previous acceleration models are verified with recent observations. A comparison is included between the acceleration behaviors of straight and turning maneuvers and the influence of speed limits on acceleration rates, and two new polynomial models are developed for driver acceleration behavior for turning maneuvers versus straight maneuver acceleration from a stopped condition.
Highway Capacity Manual and Highway Capacity Software 2000 and Advanced Transportation Modeling Tools: Focus Group Findings
Authors: Flannery Aimee , Anderson Andrea , Martin Angela
Published: April 2007

Focus groups were conducted in several cities throughout the United States and Canada between June 2002 and July 2003 to gain insight into the use of the newly released Highway Capacity Manual (HCM) 2000 and to understand better how professionals choose advanced modeling tools. Part I of the HCM 2000 was noted as being a good reference for both laypersons and those working with the HCM on a daily basis. Part V was noted as needing improvement to be useful to professionals, including more specific information regarding model strengths and weaknesses. In regard to the use of computer-based models, more than 80% of the participants use the HCM and the Highway Capacity Software to analyze operational performance and estimate capacity of highway systems. For advanced modeling techniques, 70% of those surveyed turn to SYNCHRO, but few participants could say why they had chosen a particular software package other than being directed by a sponsor agency to use it. It is noted that focus groups are a useful means to obtain qualitative and quantitative information regarding the use of the HCM 2000 and to identify areas of the manual that need improvement and further research. In addition, the information gleaned from this study points to the need for guidance regarding the selection and application of advanced transportation modeling tools. Finally, it is noted that additional focus groups should be held to include opinions from other user groups including planners, decision makers, and designers.
Impact of Traffic Congestion on Bus Travel Time in Northern New Jersey
Authors: McKnight Claire E. , Levinson Herbert S. , Ozbay Kaan , Kamga Camille , Paaswell Robert E.
Published: April 2007

Traffic congestion in Northern New Jersey imposes a substantial time operational penalty on bus service. The purpose of a project was to quantify the additional travel time that buses need because of traffic congestion. A regression model was developed to estimate the travel time rate (in minutes per mile) of a bus as a function of car traffic time rate, number of passengers boarding per mile, and the number of bus stops per mile. The model was used to estimate the bus travel time rate if cars were traveling under free-flow conditions, and the results were compared with the observed bus travel times.
Demand Forecasting and the Americans with Disabilities Act: Orange County, California, Transportation Authority's Access Program
Authors: Menninger-Mayeda Heather , Berger Peggy M. , Berger Dale E. , McCormick Beth , Boyle Daniel K.
Published: April 2007

A sound empirical basis for forecasting public transit's complementary paratransit ridership is critical as these programs grow and develop budgets that threaten to eclipse fixed-route operations, even as court interpretations of the Americans with Disabilities Act (ADA) narrow the latitude of operators. A reliable demand model that can be adapted to reflect change is a powerful planning tool in the evolution of ADA complementary paratransit services. Orange County Transportation Authority (OCTA) in California sought a model to provide a forecast of Access service ridership over 5 years. The model was developed from extensive time series analyses of archived records of 1.8 million daily boardings over a 34-month period within a larger study effort that included a peer survey, selected census data analysis, and community outreach. This model predicts OCTA's daily ADA one-way passenger boardings. Daily predictions can be aggregated to generate forecasts monthly, quarterly, or yearly. The current model with 15 predictor variables provides an extremely close fit to actual ridership, offering a balance of accuracy and practicality. This model has value to practitioners and researchers alike because the key variable of average daily ridership is readily available and enables the model's use and validation in a range of public transit settings. Also, the model can predict variables such as revenue hours and miles for given peak periods. Three methods are presented for adapting the model to accommodate either temporary or permanent change. The model's basic input is daily ADA ridership numbers for a 2- or 3-year period. The model's output represents not latent demand, but demand likely to present for services.
Mainstreaming Intelligent Transportation Systems: Survey of California Leaders
Authors: Deakin Elizabeth
Published: April 2007

Factors affecting the implementation of intelligent transportation systems (ITS) as a "mainstream" transportation planning activity are investigated. Interviews with 51 leaders from a cross section of jurisdictions and agencies in California are drawn upon. The interviews revealed that the vast majority of elected officials and senior staff are familiar with ITS but are irritated by ITS literature, which they view as heavily promotional and full of jargon. Many believe that ITS is being implemented fairly quickly overall and that ITS elements that are not proceeding well suffer from institutional problems or market weaknesses. Respondents do not see a problem in fitting ITS projects into mainstream transportation planning processes, but they complain of a lack of good information on ITS benefits and costs. Many are concerned that ITS evaluations have not been conducted objectively and focus too heavily on system benefits rather than traveler benefits. Many believe that the private sector should be left to implement some ITS applications while they agree that earmarking funds for ITS applications would speed their implementation. Respondents suggest that the state department of transportation should lead by example and implement ready-to-go technologies on its own facilities and within its own agency. Respondents also recommend building stronger partnerships with local government and other state agencies and developing mutually beneficial, multipurpose applications. Finally, respondents urge that future ITS work should pay more attention to legal and institutional issues and provide a clearer sense of "next steps." The findings should be of use to state and local organizations with an interest in encouraging ITS implementation.
What We Know Now That We Wish We Knew Then About Intelligent Transportation Systems: A Retrospective on the 1992 Strategic Plan
Authors: Sussman Joseph M.
Published: April 2007

From September 1991 until June 1992, a core writing team worked on what was the first intelligent transportation systems (ITS) strategic plan in the United States. This plan was entitled "A Strategic Plan for IVHS [Intelligent Vehicle Highway Systems] in the United States." It defined the ITS program at a national scale in a way that has been characterized as seminal. The plan, by most accounts, served as the blueprint for the early development of ITS in the United States and as the basis for subsequent plans produced by ITS America, the federal government, various states, and a number of private-sector organizations. Various aspects of ITS are explored retrospectively, contrasting views from 11 years ago, when the strategic plan was produced, with the current reality. Areas discussed include advanced traveler information systems, advanced transportation management systems, reliability, getting the ITS program off the ground in the early 1990s, strategic use of information, automated network management, electronic toll collection, congestion pricing, architecture, commercial vehicle operations, advanced public transportation systems, and regions. ITS is compared with the Interstate system, and a discussion covers both the upcoming reauthorization of the Transportation Efficiency Act for the 21st Century and the knowledge that has been gained through this retrospective about ITS-related issues on that reauthorization.
Adaptive Planning for Dealing with Uncertainty in Implementing Advanced Driver Assistance Systems
Authors: Marchau V. A. W. J. , Walker W. E.
Published: April 2007

Much has been written about the technologies of advanced driver assistance systems (ADAS)—electronic systems that support drivers in controlling their vehicles. Within this literature, the focus is usually on specific ADAS technologies and aspects of ADAS implementation. Broader pictures of ADAS implementation, in which the various ADASs, their possible consequences for transportation-system performance, and societal conditions for implementation are treated in an integrated way, are seldom presented. As such, the current value of these studies is highly limited with regard to public policymaking. In addition, full-scale implementation of ADAS is limited by uncertainties about its performance and driver acceptance. A flexible or adaptive policy is proposed that takes some actions right away and creates a framework for future actions that allow for adaptations over time as knowledge about the performance and acceptance of ADAS accumulates and critical events for ADAS implementation take place. The adaptive approach is illustrated in the context of ADAS for road-traffic efficiency.
Estimation of Statewide Urban Public Transit Benefits in Tennessee
Authors: Southworth Frank , Vogt David P. , Curlee T. Randall
Published: April 2007

A comprehensive transit benefits assessment procedure is described as applied to each of the 12 urban public transit operating districts in the state of Tennessee. A multiple-branch benefits assessment tree is developed around transit use benefits and transit supply benefits, the former emphasizing the costs of lost mobility in the absence of current transit services and the latter reflecting the economic benefits resulting from federal and state support for public transit in each district. Empirical results are presented at the statewide level and in dollar terms. With a generally conservative approach to benefits estimation, it is found that urban transit benefits—mainly from fixed-route bus service—exceed costs by 2 to 2.5 times, with higher ratios possible in the larger metropolitan areas. Sensitivity to forgone travel benefits, however, suggests the need for further data refinements. On the basis of past literature, the study develops a comprehensive set of wide-ranging benefits computations that have been applied consistently across each of the state's 12 urban transit districts and uses data sources that can be cost-effectively updated by transit planners.
Tripperpas Smart Card Project: Lessons from the Netherlands
Authors: Cheung Francis
Published: April 2007

Tripperpas was an electronic smart card that enabled users to travel and pay for bus journeys in the municipality of Groningen, the Netherlands. Between January 2000 and December 2002, Tripperpas could be purchased and used on the bus network served by Arriva. The objectives of the experiment were to determine the efficacy of the contactless chip card technology and to assess the acceptability of the new ticketing method in a working urban environment. The practical experience gained could be used to guide the development and implementation of a nationwide electronic ticketing system. In the 2-year trial period, more than 4,000 Tripperpas were used. To monitor progress and evaluate performance, surveys were conducted (one before and three after) with questionnaires, focus group discussions, and in-depth interviews. The goals were to elucidate passenger experiences and staff responses. Additional surveys were conducted to investigate the reactions of nonusers and ex-users. The research findings presented a comprehensive picture of the strengths and weaknesses of Tripperpas compared with the conventional strip ticket. They also provided valuable insight into travel behavior as well as staff and passenger preferences. Research outcomes will assist the introduction of a nationwide electronic ticketing system in the near future.
Aviation Network Design in Taiwan
Authors: Dai Melody D. M. , Lin Cheng-Chang , Liou Jong Shyang
Published: April 2007

To analyze intercity multimodal transportation choices, an aviation network design model was developed to consider all transportation modes relative to daily airport capacity under different demand conditions in the determination of route availability and frequency. The factors in the model include the travel time of various modes (ground access time included), operating cost of various modes, travel demand, airport capacity, and aircraft-type restrictions for each route. A network flow problem with side constraints was formulated. To solve this problem efficiently, a heuristic algorithm was developed by incorporating Lagrangian relaxation, the shortest-path algorithm, and the subgradient method. The performance of this algorithm was compared with the exact solution for a network of five metropolitan area centers. The results show that the gap between these two is only 1.28%. In addition, a case study of a real network was conducted. This network differed from the exact solution by 0.274%. The study verifies that the flight frequency for each route and the passenger route choices, which were obtained with the heuristic algorithm, are feasible and reasonable. Thus, the model and the heuristic algorithm could be applied to real situations and provide insight for restructuring an aviation network.