bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Cement-Treated Open Graded Drainage Layer Placement Techniques in Ontario, Canada
Authors: Kazmierowski Tom , Marks Pamela , Paulerson Paul
Published: April 2007

The effectiveness of the subsurface drainage system is a primary factor influencing long-term pavement performance. Pavement research indicates that pavement drainage systems increase pavement life and lower maintenance costs by minimizing the risk of subgrade softening and differential frost action. For rigid pavements, optimum transverse joint performance is achieved when the concrete pavement overlies a highly permeable base layer, promoting subsurface drainage, as well as a layer that is structurally stable, providing uniform support to the slab. This type of slab support eliminates the potential for loss of slab support from fine migration from pumping action over time. The Ministry of Transportation of Ontario (MTO), Canada, recognizes the benefits of high-performance pavement drainage systems and several years ago adopted open graded drainage layers (OGDLs) for design of freeways. The MTO OGDL has an open void structure with a laboratory-determined permeability on the order of 10-2 cm/s by using aggregate with a very low fines content. To achieve stability, 100 percent crushed bedrock aggregate is specified, and since the late 1980s, MTO has specified the use of an asphalt-treated OGDL with 1.8 percent asphalt cement to facilitate placement. The material development and subsequent construction and quality control activities completed during construction of test sections on a major freeway in southern Ontario in 1996 and 1997 are outlined. The work conducted along with the trials established that a portland cement-treated OGDL placed with conventional asphalt paving equipment is a viable alternative to asphalt-treated OGDL on the basis of costs and drainage properties.
Microstructural Stability of Sulfate-Contaminated Crushed Concrete Treated with Cementitious Materials
Authors: Sarkar Shondeep L. , Little Dallas N.
Published: April 2007

Severe sulfate contamination in a crushed concrete base had resulted in considerable expansion of the base and total decomposition of the matrix, attributed to the formation of copious amounts of calcium sulfoaluminate hydrate and calcium silicosulfate hydrate minerals, ettringite and thaumasite, respectively. Incorporation of low volumes ranging from 5 to 13 percent (by mass) sulfate-resistant Type V cement was tested as a means of arresting the expansion and thus stabilizing the base. Class C fly ash was also introduced into the mixtures to dry the material to an acceptable moisture content for reworking and compaction. The presence of large amounts of calcium sulfoaluminate minerals promoted high levels of moisture retention within the base. These cementitious material-treated mixtures were subjected to different environmental conditions for 18 months, during which time their performance was evaluated. Their microstructural stability, evaluated by optical microscopy, scanning electron microscopy/energy dispersive X-ray analysis, X-ray diffraction, and differential thermal analysis/thermogravimetric analysis, is discussed.
Destination and Mode Choice Models for Nonmotorized Travel
Authors: Eash Ronald
Published: April 2007

Until recently, few work programs of metropolitan planning organizations (MPOs) included planning for pedestrians and bicycles. This situation is changing as MPOs respond to the availability of federal funding for pedestrian and bicycle facilities, the efforts of bicycle and quality-of-life advocacy groups, and air quality conformity requirements that limit growth in vehicle trips. Walking and cycling cannot be introduced easily into MPO travel forecasting models due to the different scales of nonmotorized and vehicle trips. Analysis zones and coded networks for forecasting vehicle travel are typically too coarse for the trips of pedestrians and cyclists. Vehicle models also are based on certain theories of travel behavior that seem inappropriate for nonmotorized travel. Models for nonmotorized destination choice and vehicle versus nonmotorized mode choice have been calibrated and applied at the Chicago Area Transportation Study as part of a regional model. The two nonmotorized models feature a different zone system than the vehicle models and measure the difficulty of nonmotorized travel without a coded network. How these nonmotorized models were calibrated and implemented in the regional model is shown. Model estimates of walking and cycling trips are presented and compared against census work-trip data and a recent household travel survey.
Evaluation of Pedestrian Walking Speeds in Airport Terminals
Authors: Young Seth B.
Published: April 2007

Despite the fact that significant investment has been made to install automated pedestrian movement systems within airport terminals, little is known about their effects on airport pedestrian flows. Specifically, while walking speeds of pedestrians have been studied in general, such analysis specific to airport passengers has been lacking. New insight into the walking speeds of airport pedestrians is provided. Corridors with and without moving walkways, the most common of airport automated pedestrian movement systems, are considered. Pedestrian movements in various airport terminal corridors are empirically observed, and observed walking speeds are compared with those of research performed in other transportation terminals. Furthermore, the effects on walking speeds of observable characteristics of pedestrians and the surrounding environment are investigated. The effect of moving walkways on pedestrian walking speeds is examined. A methodology for estimating the travel time of pedestrians on moving walkways under various traffic-flow conditions is derived. Application of the methodology using empirically collected data reveals interesting results about the movement of pedestrians through corridors with moving walkways. The analysis presented may be used to estimate expected travel times in airport corridors, and to examine the effects of potential infrastructure investments on such times. The goal of such an analysis is to improve the quality of service at the airport terminal, particularly for the pedestrians who traverse its corridors.
Analysis of Factors Contributing to "Walking Along Roadway" Crashes
Authors: McMahon Patrick , Duncan Chandler , Stewart J. , Zegeer Charles , Khattak Asad
Published: April 2007

There are a variety of factors widely acknowledged to have an impact on the risk of pedestrian motor-vehicle injuries. The factors that have been most extensively researched are geometric characteristics of the road, including the presence of sidewalks. In relevant epidemiological research, however, factors relating to demographics and neighborhood characteristics have been alluded to but not sufficiently researched. A case-control methodology has been used and conditional and binary logistic models have been applied to determine the effects of cross-sectional roadway design attributes and socioeconomic and other census block-group data on the likelihood that a site is a crash site. Analyzed were 47 crash sites and 94 comparison sites. Physical design factors found to be associated with a significantly higher likelihood of being a crash site are a higher speed limit; the lack of wide, grassy walkable areas; and the absence of sidewalks. When these roadway factors are controlled for, nongeometric factors associated with a significantly higher likelihood of being a crash site are high levels of unemployment, older housing stock, lower proportions of families within households, and more single parents. This information suggests that some neighborhoods may, due to increased exposure or specific types of exposure, be especially appropriate sites for pedestrian safety measures such as sidewalks, lower-speed roadway designs, and the addition of wide, grassy shoulders.
Use of Animated "EYES" So That Motorists Leaving an Indoor Parking Garage Look for Pedestrians
Authors: Van Houten Ron , Van Houten Joy , Louis Malenfant J. E. , Donrus Don
Published: April 2007

Approximately 14 percent of reported pedestrian crashes occur on private property, most often in a commercial or other parking lot. One way to increase pedestrian safety where the sidewalk crosses the exits of indoor and outdoor parking garages is to prompt motorists to look for pedestrians when exiting the garage. As a possible countermeasure, an animated "EYES" display was erected at an indoor parking garage exit. The animated EYES signal head included two eyes with eyeballs that scanned from left to right at a rate of one cycle per second. Analysis of the data collected during the study indicated that more than a third of the motorists leaving the garage did not look in either direction for pedestrians before crossing the sidewalk. The introduction of the animated EYES increased motorists' observing behavior and reduced pedestrian-motor vehicle conflicts.
Factors Influencing Bicycle Crash Severity on Two-Lane, Undivided Roadways in North Carolina
Authors: Klop Jeremy R. , Khattak Asad J.
Published: April 2007

Concern over crashes involving bicycles and motor vehicles is largely due to the severity of injuries. The impacts of physical and environmental factors on the severity of injury to bicyclists are examined. North Carolina Highway Safety Information System crash and inventory data for state-controlled, two-lane, undivided roadways are analyzed. The injury severity distribution, measured on the KABCO scale, is as follows: no injury, 1.8 percent; complaint of pain, 24.4 percent; nonincapacitating injury, 42.5 percent; incapacitating injury, 25.5 percent; and fatal injury, 5.9 percent. The total number of involvements in this data set was 1,025, with a majority of the involvements occurring outside urbanized areas (80.5 percent). Using the ordered probit model, the effect of a set of roadway, environmental, and crash variables on injury severity is explored. Variables that significantly increase injury severity include straight grades, curved grades, darkness, fog, and speed limit. Higher average annual daily traffic, an interaction of speed limit and shoulder-width variables, and dark conditions with street lighting significantly lower injury severity. Separate models are estimated for rural and urban locations. Marginal effects of each factor on the likelihood of each injury-severity class are reported. Policy implications and possible countermeasures are then discussed.
Development of a Computer Simulation Model of Mixed Motor Vehicle and Bicycle Traffic on an Urban Road Network
Authors: Faghri Ardeshir , Egyháziová Erika
Published: April 2007

The first step has been taken in the effort to develop a microscopic simulation model of mixed motor vehicle and bicycle traffic over an entire network. The primary objective was to develop the main algorithm of BICycle SIMulator and translate it into a working computer program. To achieve the goal, the gaps in the existing literature were filled by data collected at the University of Delaware campus in Newark. An equation of mixed bicycle and motor vehicle following was developed and used for the representation of longitudinal interaction of vehicles. The program was implemented in C+plus; programming language and tested on real-world data. The resulting software is the first in the world to allow the inclusion of bicyclists in the analysis of urban transportation by the means of microscopic simulation.
Forecasting Bicycle and Pedestrian Travel: State of the Practice and Research Needs
Authors: Porter Christopher , Suhrbier John , Schwartz William
Published: April 2007

A review has been implemented on the state of the practice and research needs have been identified on methods for forecasting bicycle and pedestrian travel. The focus is on methods that forecast how many people will use a new bicycle or pedestrian facility or how many additional people will walk or bicycle in response to facility or network improvements. Overall, there appears to be a shortage of methods that practitioners with limited technical resources can use but are nonetheless accurate enough for planning purposes. In addition, existing research on the factors influencing the decision to walk or bicycle often has not been translated into usable forecasting methods. Three major recommendations are made. First, in the short term, a sketch-planning manual for bicycle and pedestrian forecasting is needed to give planners access to the basic data, tools, and methods required to estimate future demand. Second, further research is needed into specific factors influencing bicycle and pedestrian travel behavior, with an emphasis on identifying key factors that can be included in forecasting models. Third, bicycle and pedestrian considerations should be integrated into mainstream transportation models that traditionally have focused on vehicle travel. Inclusion of nonmotorized modes in travel models will improve capabilities for forecasting both motorized and nonmotorized travel and will help place bicycles and pedestrians on a "level playing field" with motorized modes in transportation planning.
Review of Basic Research in Bicycle Traffic Science, Traffic Operations, and Facility Design
Authors: Taylor Dean , Jeffrey Davis W.
Published: April 2007

Recent emphasis on alternatives to automobile transportation has brought to light deficiencies in basic research performed in bicycle traffic science. Because of limited opportunities to fund such research, it is prudent to use past research to develop design guidelines and provide a basis for planning future research efforts. Mainly toward the latter end, a comprehensive review of published basic research in bicycle traffic science (with relevance to U.S. traffic) is presented, and suggestions are made for research priorities.
Effects of Stray Currents on Performance of Metallic Reinforcements in Reinforced Earth Structures
Authors: Sankey John E. , Anderson Peter L.
Published: April 2007

For two decades, designers of railway systems worldwide have found Reinforced Earth to be ideally suited for support of track beds and bridge and trestle abutments, for earth retention structures adjacent to rights-of-way, and for deflection walls to protect bridge piers from impact in the event of derailment. Stray currents from direct current traction power railways have been shown to be of little concern in corrosion of the metallic soil reinforcements used in Reinforced Earth structures. The discrete metallic reinforcements used in Reinforced Earth structures lack electrical continuity, so the reinforcements act as individual short length conductors instead of part of a continuous network. Therefore, there is no tendency for stray currents to collect on individual reinforcements, accumulate as a result of electrical continuity, and discharge to the earth at remote locations. Select backfill that conforms to the standard mechanical and electrochemical requirements for Reinforced Earth structures provides additional resistance to the flow of stray currents. Several examples of the performance of galvanized reinforcing strips in stray current situations are provided. It is noted that galvanized steel reinforcements without a cathodic protection system have been the predominant choice since 1990.
Evaluation of Global Positioning System Devices for a Quality Control System for Compaction Operations
Authors: Do Won-Seok , Oloufa Amr , Thomas H.
Published: April 2007

Quality control of the compaction process is an important concern for owners and contractors because compaction is essential for improving the stability and density of construction materials such as soils and asphalt. When other conditions such as roller frequency, wheel load, and compactor speed are the same, the density of asphalt pavement depends on the number of coverages of the compactor. If the mat is compacted with less than the determined number of passes, the result may be a large volume of air voids, leading to low density. However, if the mat is overly compacted, the aggregates will be crushed further and the attributes of the mix will be changed, leading to a reduction in density. For this reason, monitoring the exact number of coverages over the entire surface of the pavement mat is desired. Research that started 3 years ago to develop an automated system for mapping compaction equipment using global positioning system (GPS) technology is reported. The objective of this research is to test the GPS receiver under various conditions of compaction operations. The researchers conclude that the accuracy of GPS devices selected should be better than 15 cm, the typical asphalt coverage overlap.
Analysis of Individuals’ Joint-Activity Engagement Using a Model System of Activity-Travel Behavior and Time Use
Authors: Fujii Satoshi , Kitamura Ryuichi , Kishizawa Keiko
Published: April 2007

With the recognition that joint-activity engagement should be analyzed not only for more accurate travel-demand forecasting but also for better assessment of transportation policy options, individuals’ joint-activity engagement with other individuals is analyzed using activity diary data. First, a structural equations model system is developed. Its exogenous variables represent activity engagement with family members, with other individuals, or by oneself, and in home or out-of-home, and its endogenous variables also represent travel patterns and subjective assessment of the quality of life. The results of model estimation indicate that travel patterns and subjective assessments of the quality of life depend on joint-activity engagement quite substantially. Following this analysis, a model of time allocation is developed using diary data and stated preference (SP) data that are based on the assumption of random utility maximization. The model system is formulated as a structural Tobit model system that accounts for the correlation between error terms. In the modeling formulation, SP responses on time allocation are combined with revealed preference (RP) observations on time allocation, and relations among latent preference factors are incorporated. The modeling approach is believed to be effective for modeling out-of-home joint-activity engagement with other individuals, which is an important element in travel-demand analysis but may be difficult to account for by RP variables alone. Time-use patterns for joint activities are also shown to depend on personal and household attributes.
Drivers’ Learning and Network Behavior: Dynamic Analysis of the Driver-Network System as a Complex System
Authors: Nakayama Shoichiro , Kitamura Ryuichi , Fujii Satoshi
Published: April 2007

A model system of drivers’ cognition, learning, and route choice is formulated, taking into account the limitations in drivers’ cognitive capabilities, and is applied to examine the dynamic nature of a driver-network system through microsimulation. Network equilibrium is not assumed a priori; rather, finding how an equilibrium is reached, or not reached, is the objective. Although equilibrium analysis, in general, focuses on unique and static equilibrium by treating drivers’ behavior as simply as possible, drivers’ behavior is treated more realistically to enhance understanding of the day-to-day dynamics of the driver-network system. Results of microsimulation analyses indicate that the network flow does not necessarily converge to user equilibrium; instead, it may reach “deluded equilibrium,” which is caused by drivers’ false perceptions of travel times, and have “path dependence.” Results, especially the complex behavior such as path dependence shown in the simulation, indicate that the driver-network system is a complex system.
Multimodal Daily Itinerary Planner: Interactive Programming Approach
Authors: Chen Cynthia , Kitamura Ryuichi , Chen Jiayu
Published: April 2007

With limited information and computational capability, travelers (especially tourists) often fail to develop an itinerary that best suits their needs. A computer software program called Itinerary Planner was developed to help travelers find a suitable itinerary by generating alternative travel itineraries. Compared to existing trip planners, the Itinerary Planner is unique in three aspects: ( a) it considers multimodal itineraries; ( b) it is capable of handling multiple constraints, including time windows for arrival and departure times, or mode constraints; and ( c) the Itinerary Planner adopts an interactive programming approach to identify the best itineraries for the user. Through iterative interaction with the user, the planner attempts to gauge the preferences the user has with respect to selected travel attributes (e. g., travel time and travel cost) and apply the resultant preference estimates to evaluate all feasible itineraries. A prototype planner is developed for downtown San Francisco. It is demonstrated that the planner is capable of effectively generating alternative itineraries for a tour that involves multiple trips and multiple modes, with complex constraints. Although the current prototype contains some limitations, the planner prototype promises that it can be further developed as a practical tool for itinerary planning. The planner presents a new way to save travel time, to relieve traffic congestion, and to encourage transit use by helping travelers organize their trips in an efficient manner.
Role of Congestion and Information in Trip-Makers’ Dynamic Decision Processes: Experimental Investigation
Authors: Srinivasan Karthik K. , Mahmassani Hani S.
Published: April 2007

The role of congestion and information on trip-makers’ dynamic decision processes, particularly commuters’ route- and departure-time-switching behavior, is investigated. Using data from interactive simulation experiments, indifference bands for route- and departure-time-switching decisions are calibrated based on a boundedly rational behavioral framework. Trip-maker behavior is influenced not only by the magnitude of congestion but also by its day-to-day evolution. Both information quality and the interaction between information, behavioral inertia, and traffic supply conditions are significant determinants of behavior. Trip-makers’ short-term and longer-term experiences in traffic strongly influence route- and departure-time-switching decisions. These findings have important implications for dynamic traffic modeling, network state prediction, design of Advanced Traveler Information Systems products and services, and assessment of Intelligent Transportation Systems impacts.
Exploratory Longitudinal Analysis of Solo and Joint Trip Making Using the Puget Sound Transportation Panel
Authors: Chandrasekharan Balasubramanian , Goulias Konstadinos G.
Published: April 2007

The Puget Sound Transportation Panel is used to study the propensity of people to make solo and joint trips. The analysis consists of trip-based models in which solo versus joint trip making is explained in terms of person and household sociodemographics, daily activity and travel patterns, dwelling unit and workplace level of service and land use characteristics, and trip attributes. The analysis is repeated for all the days and all the waves (years) of the panel at hand. The analysis reveals that the major factor that determines joint trip making is the life-cycle stage of the household. It is also observed consistently across all the waves that, as the age of the person increases, the number of joint trips he or she also increases. Other factors that consistently affect joint trip making are household size, age of the household members, number of vehicles in the household, daily activity and travel patterns, and certain accessibility measures such as the access from transit to auto.
Household Activities, Life Cycle, and Role Allocation Tests on Data Sets from Boston and Salt Lake City
Authors: Stopher Peter R. , Metcalf Helen M. A.
Published: April 2007

Tests of four hypotheses relating to allocation of activities and time among household members are described using two data sets from two urban regions—Boston, Massachusetts, and Salt Lake City, Utah. The first hypothesis is a test of categorizing activities into groups of mandatory, flexible, and optional activities; this hypothesis is upheld by the data. The second hypothesis is a test of whether there are significant differences in the mean time allocations of activities among the life-cycle groups. It was found that the life-cycle groups that were used do provide a basis for identifying significantly different time allocations to different activities within all three groups of activities. The third hypothesis concerns the relative allocation of time by gender within households for optional and flexible activities, across the life-cycle groups. It was found that gender shows effects on time allocation, but these effects are limited to a few activities, and others show no such effects. The fourth hypothesis concerns the allocation of time by gender and working status. Again, it was found that, for some optional and flexible activities, there are significant differences both in working status and between genders within working status. However, the differences appear only for a subset of activities. Overall, the results show a high degree of similarity between Boston and Salt Lake City and also to an earlier set of tests on a much smaller subsample of Boston data.
Link-Journey-Speed Model for Arterial Traffic
Authors: Zhang H. M.
Published: April 2007

Real-time traffic information, such as travel time or its inverse—journey speed—is critical to the successful implementation of advanced traveler information systems. Yet it is often costly to measure travel time or journey speed directly. Reliable methods have been developed to estimate travel time and journey speed for freeways. Estimation models for arterial travel time, however, are lacking. A simple model for estimating travel speed over an arterial link is presented. The model combines two speed estimates—one from critical volume to capacity ratio and the other from volume and occupancy measured by loop detectors—to produce more accurate estimated link journey speeds that can be used to provide real-time assessment of traffic congestion levels on arterial streets. A preliminary evaluation of the proposed model is also provided, and the model is compared with two other arterial travel time models. Limitations of the model are explained, and areas for potential improvement are suggested.
Method To Enhance Performance of Synthetic Origin-Destination Trip-Table Estimation Models
Authors: Sivanandan R. , Nanda Dhruv , Arnold Eugene
Published: April 2007

The conventional methods of determining origin-destination (O-D) trip tables involve elaborate surveys, such as home interviews, that require considerable time, staff, and funds. To overcome this drawback, a number of theoretical models that synthesize O-D trip tables from link volume data have been developed. Two of these models—The Highway Emulator (THE) and the Linear Programming (LP) model—are considered. These models use target/seed tables for guiding the development of output trip tables. In research conducted by the Virginia Techical Center for Transportation Research for the Virginia Transportation Research Council, it was determined that use of a superior target/seed table potentially could enhance the performance of these models. Readily available socioeconomic data and link-volume information were used to develop a methodology for obtaining an enhanced target/seed table through application of the trip-generation and trip-distribution steps of the four-step planning process. The enhanced table then was used as the target/seed to the LP and THE models, and their performance was evaluated. The closeness of the output tables to surveyed tables and their capability to replicate observed volumes were studied. Also analyzed were the output tables’ improvements when a structural table was used as target. Tests showed that the use of the enhanced target/seed table significantly improved the performance of the LP model. However, mixed trends were obtained for the THE model.
Travel-Time Prediction for Freeway Corridors
Authors: D’Angelo Matthew P. , Al-Deek Haitham M. , Wang Morgan C.
Published: April 2007

The application of a nonlinear time series model to the prediction of traffic parameters on a freeway network is investigated. The nonlinear time series approach is a statistical technique that has strong potential for on-line implementation. A new approach for predicting corridor travel times is developed and tested with travel-time data. The travel-time data are derived from observed speed data, which are collected from an 18-km (11.2-mi) freeway section in Orlando, Florida. The westbound Interstate-4 morning peak period (6:00 to 10:00 a.m.) for 20 incident-free days is tested with the goal of predicting recurrent congestion. The problem is addressed from the perspectives of single-variable and multiple-variable prediction of corridor travel times. In single-variable prediction, speed time-series data are used to forecast travel times along the freeway corridor. A calibrated single-variable prediction model is developed through the application of decay factors to smooth out the input data and the establishment of a threshold on the minimum speed prediction permitted. Multivariable prediction schemes are developed using speed, occupancy, and volume data provided by inductive loop detectors on the study section. The prediction performance of the calibrated single-variable model is shown to be superior to the multivariable prediction schemes. This new approach produces reasonable errors for short-term (5-min) travel-time predictions. The developed model can be implemented on-line with minimal effort.
Trip Generation Study of Passenger Rail Station at Providence, Rhode Island
Authors: Young Henry S. , Shaw Robert B. , Lee K. Wayne
Published: April 2007

The results of a comprehensive trip generation study of the Providence Railroad Station in Providence, Rhode Island, are presented. The results include the monitoring of vehicular traffic approaching and departing on streets adjacent to the station and making stops for arriving or departing rail transit passengers. Daily train schedules were obtained for each observation period to determine the number of train stops per day (an independent variable). Social and environmental effects that could influence transit ridership (holidays, weather, and so forth) were noted. Finally, the characteristics that define the station and the community it services were researched and presented. It was found that the peak period for vehicular traffic generated by the station occurred on Monday mornings when commuter peak hour occurred combined with interstate Amtrak train service. The trip generation data resulting from the study can be used to make general predictions regarding trip generation trends at other rail transit stations that have similar service and environmental characteristics. The trip generation report will also contribute to the ongoing research necessary to develop accurate trip generation estimates for railroad stations.
Using Simple Simulation Models in Operational Analysis of Rail Transit Lines: Case Study of Boston’s Red Line
Authors: Heimburger Douglas E. , Herzenberg Anne Y. , Wilson Nigel H. M.
Published: April 2007

This paper explores the operational performance of the Massachusetts Bay Transportation Authority (MBTA) Red Line, a conventional heavy rail line, using a simple computer simulation model developed specifically for this purpose. The model incorporates most of the important variables that affect performance, including the signal system, passenger flow, the train station dwell time, and realistic train and operator behavior. The model was used to analyze the minimum achievable headway on the line and to examine whether a reduction in the scheduled number of trains operating in the peak period could be made without negatively affecting service quality. Experiments with the simulation model demonstrated that MBTA could indeed reduce the number of trains operating in the evening peak period without degrading service quality. Based on these results, MBTA implemented a new timetable that reduced operational costs at the same time as reducing train delays on the line, without any significant negative effects on passenger service.
Inner Zone Commuter Rail as an Opportunity for Light Rail: Lessons from Boston’s Riverside Line
Authors: Allen John G.
Published: April 2007

Several closer-in commuter rail routes face a stagnant future as they are presently operated. The core markets best suited for commuter rail have moved farther into the suburbs, yet transit authorities are politically reluctant to rationalize their inner-zone lines and stations. As a result, most managements sustain these lines at a minimum level, without making major investments in their future. Massachusetts Bay Transportation Authority-Boston’s Riverside Line converted a poorly used commuter rail line into a modern light rail line in 1959. At affordable cost, the transit authority was able to achieve a quantum leap in service ferequency and ridership. The Riverside experience shows that poorly performing inner zone commuter rail lines can be revived as light rail if market conditions are favorable. Philadelphia’s Schuylkill Valley Metro, now in active planning, follows the Riverside Line’s lead, as do existing operations in Karlsruhe, Saarbruecken, Newcastle, Manchester, and Buenos Aires. Promising opportunities for conversion of commuter rail to light rail may exist elsewhere in Philadelphia and in Chicago.
Personal Rapid Transit Déjà Vu
Authors: Sulkin Maurice A.
Published: April 2007

Although the basic concept of personal rapid transit (PRT) was originally explored at an earlier time, the decade from about 1965 to 1975 saw a flurry of interest and activity in the PRT field. During that period, the highly successful Morgantown PRT system was developed and built on the campus of the University of West Virginia in Morgantown. That system is still operating effectively and is currently upgrading its automatic control system technology, now about 30 years old. Little more had been accomplished in the PRT field until recent years when Chicago and Raytheon joined forces in a project aimed at developing and installing a PRT system in Rosemont, adjacent to O’Hare Airport. The Raytheon PRT 2000 system, currently operating on a factory test track in Marlborough, Massachusetts, is the first serious PRT activity since the Morgantown system was implemented 25 years ago. Much has been written in the intervening years about the benefits of PRT as applied to densely developed urban centers. There are, however, some substantial technical obstacles to attaining the full potential of those systems. Three types of obstacles are discussed. These obstacles involve limitations on station interval, size, and complexity requirements for high-capacity PRT stations, and how they affect system operational availability. These factors are examined in the context of a comprehensive system serving a densely developed central business district instead of the limited application as exemplified by the Morgantown system.
Arterial Planning Methodology: Concept, Implementation, and Experience
Authors: Prassas Elena Shenk , McLeod Douglas
Published: April 2007

The Highway Capacity Manual (HCM) did not originally contain an arterial planning methodology, but the state of Florida perceived an acute need for one in order to meet its obligations for growth management. Such a methodology was developed, documented, and implemented throughout the state. The methodology was firmly based upon the HCM detailed analysis procedure but had assumptions and defaults that allowed a range of planners to use it effectively. The basic construct was to provide tables of design volumes v and annual average daily traffic that could be achieved for various levels of service and signal spacings for the default parameter values. Two computational tools, implemented in the form of spreadsheet templates as being the most user-friendly and open approach, were provided to users so that they could modify the default settings or specify particular signal spacings and such. The methodology has been in widespread use in Florida, it has served as the basis for the arterial planning technique incorporated into the last update to the HCM, and other states have requested information. The experience with the implementation, including training needs and common user questions, is recounted.
Improving the Running Times in Highway Capacity Manual Table 11-4; Related Observations on Average Travel Speed
Authors: Prassas Elena Shenk
Published: April 2007

An arterial planning methodology has been in use in Florida for several years and influences decisions in developments of regional impact and other analyses. It is incorporated into the Florida Level of Service Manual. Experience has indicated that analysts using the default values are concerned that the average travel speeds are underestimated by 10 km/h or more. Given the known limits of the data underlying the arterial running time and running speed default estimates in the Highway Capacity Manual (HCM), it was decided to conduct an extensive simulation analysis using a well-established model (NETSIM, now part of CORSIM). The findings are that ( a) simulation-derived running speed estimates are at least some 10 km/h higher than the HCM default values, ( b) moreover, the running speed estimates generally do not decrease as sharply as the HCM default values as signal density increases, and ( c) unlike the HCM default values, the simulation-derived estimates are sensitive to increased demand volume. In addition, the derived values clearly reflect the through vehicles, consistent with the original HCM intent.
Quality of Service for Uninterrupted-Flow Pedestrian Facilities in Highway Capacity Manual 2000
Authors: Milazo Joseph S. , Rouphail Nagui M. , Hummer Joseph E. , Allen D. Patrick
Published: April 2007

The objective of the research described in this paper was to develop the basis for revised operational analysis procedures for transportation facilities with pedestrian users where flow is not interrupted by traffic control devices. This paper contains both new and revised level-of-service (LOS) tables for analyzing various types of uninterrupted-flow pedestrian facilities. It details the results of a review and synthesis of American and international literature as part of a Federal Highway Administration study of pedestrian and bicycle facilities conducted by North Carolina State University between 1995 and 1998. The year 2000 edition of the U.S. Highway Capacity Manual (HCM) will incorporate, either directly or indirectly, most of the revised and synthesized information described in this paper. The research team recommends that the HCM revise the pedestrian walkway level of service to reflect the current literature. Proposed revisions include a decrease in the threshold for LOS A from 130 to 60 ft2/ped (12 to 5.6 m2/ped) and a change in the capacity level from 6 to 8 ft2/ped (0.6 to 0.75 m2/ped). The incorporation of a simplified walkway platoon level of service is recommended. In addition, given the different expectations of acceptable levels of platooning in transportation terminals, different LOS criteria are recommended for these facilities. A method of analyzing pedestrians on shared pedestrian-bicycle paths has also been identified. Although developed in the Netherlands, the procedure has been validated on at least one trail in the United States and is therefore recommended for inclusion in the HCM.
Quality of Service for Interrupted-Flow Pedestrian Facilities in Highway Capacity Manual 2000
Authors: Milazzo Joseph S. , Rouphail Nagui M. , Hummer Joseph E. , Allen D. Patrick
Published: April 2007

The objective of the research described in this paper was to develop the basis for revised operational analysis procedures for transportation facilities with pedestrian users where flow is interrupted by traffic control devices. The paper commences with some background information on pedestrian walking speeds at signalized crossings and on pedestrian noncompliance at these locations. Then both new and revised level-of-service (LOS) tables are provided for analyzing various types of interrupted-flow pedestrian facilities. Results are detailed of a review and synthesis of American and international literature as part of a Federal Highway Administration study of pedestrian and bicycle facilities conducted by North Carolina State University between 1995 and 1998. The year 2000 edition of the U.S. Highway Capacity Manual (HCM) will incorporate, either directly or indirectly, most of the revised and synthesized information described in this paper. The research team recommends that the HCM include some background information that will be helpful for analysts timing signals and performing other operations. The authors of this paper recommend assumed crosswalk walking speeds of 1.2 m/s for most areas and 1.0 m/s for crosswalks serving large numbers of older pedestrians. Another important recommendation was to use delay to pedestrians as the basis for level of service at signalized and unsignalized street crossings. The recommended threshold for LOS F at signalized crossings is 60 s or more of delay per pedestrian, whereas at unsignalized crossings it is 45 s or more of delay per pedestrian.
Progression Adjustment Factors for Uniform Delay at Signalized Intersections
Authors: Benekohal Rahim F. , El-Zohairy Yoassry M.
Published: April 2007

Signal progression plays an important role in controlling arrival pattern and delay at coordinated signalized intersections. In the Highway Capacity Manual (HCM), one random and five nonrandom arrival types are identified. The delays for nonrandom arrival cases (platoon arrivals) are computed by applying progression adjustment factors (PFs) to the delay for the random arrival case. However, HCM-estimated delays are found to be significantly different from field-measured delays for Arrival Types 1, 4, and 6. For Arrival Type 2 the HCM estimations are acceptable, although the deviations are still relatively high. For Arrival Types 3 and 5 the HCM estimates the delays accurately. These findings suggest that the HCM PFs need to be revised. A new set of PFs was developed using the arrival-based delay models. A relationship between the effective green ratio, g/C, and the new PFs was established for each arrival type. With the proposed PF values, the HCM approach would be more accurate than it is with the current PF values. For Arrival Type 1, the new PF values are higher than the current HCM values for g/C ⩽ 0.50 and lower for g/C > 0.50. For Arrival Types 2 and 4, the new PF values are lower than those of HCM, as expected, because the HCM overestimates the delays for both Arrival Types 2 and 4. For Arrival Type 6 the new PF values are lower for g/C ⩽ 0.40; otherwise they are higher. A new progression adjustment table similar to Table 9-13 of the HCM is created. It is recommended that the new PF values be adopted by the HCM since they enhance the accuracy of delay estimation.
Entering Headway for Through Movements at Urban Signalized Intersections
Authors: Al-Ghamdi Ali S.
Published: April 2007

When vehicles in a queue start crossing a stop line (or any other reference line) at a signalized intersection after the signal turns green, the entering headway (discharge headway) is the time that elapses between consecutive vehicles. This headway is a factor in determining intersection capacity. The current study aims at analyzing the entering headway at selected signalized intersections in Riyadh (the capital of Saudi Arabia). It is unlikely that driver behavior is similar in different countries, and therefore it is unwise to use the values for headway times from other countries to fit traffic conditions in Saudi Arabia. To date, no research of this type has been conducted in Saudi Arabia. This study attempts to investigate the entering headway at intersections in Riyadh and to compare the results with corresponding results from international research. Eight signalized intersections (with two-lane and three-lane approaches) along eight major streets in Riyadh were selected for study. A total of 720 single-lane traffic platoons entering the intersections were observed. It was found that the average entering headways for Vehicles 1 through 15 at two-lane intersections in Riyadh after the light turned green were 3.23, 2.41, 2.29, 2.1, 2.02, 1.84, 1.72, 1.64, 1.53, 1.68, 1.58, 1.31, 1.13, 1.19, and 1.01 s. For the three-lane sites the headways for Vehicles 1 through 13 were as follows: 3.37, 2.23, 2.03, 1.92, 1.81, 1.81, 1.72, 1.69, 1.6, 1.48, 1.37, 1.33, and 1.46 s. The study found that the saturation flow rates were 2,293 and 2,195 vehicles/hour of green per lane for two-lane and three-lane sites, respectively. These intersection approaches appear to have higher saturation flow rates than those in previous studies from other countries.
Accident and Capacity Comparisons of Leading and Lagging Left-Turn Signal Phasings
Authors: Sheffer Chris , Janson Bruce N.
Published: April 2007

Many traffic engineers nationwide are reluctant to implement lagging left-turn phasing plans along arterial streets, even though signal progression can sometimes be significantly improved. An opinion frequently expressed by traffic engineers is that lagging left turns are contrary to driver expectancy and cause an increase in start-up lost time. To prevent the “left-turn trap” in which drivers making left turns may be caught unaware of the extended opposing lagging phase, many traffic engineers do not allow permitted left turns at an intersection with lagging phasing. This study focuses only on protected left-turn phasing in which the trap does not occur. Saturation flow rates, start-up lost times, fourth-vehicle crossing times, and accident rates are compared between protected-only leading and lagging phasings. All four measures were found to be better for locations with lagging phasing than for those with leading phasing, although neither saturation flow rates nor accident rates were found to be significantly better at the 95 percent confidence level. Although further studies are needed, these findings suggest that a mix of leading and lagging protected-only phasing may be used to gain signal coordination advantages without compromising safety or capacity.
Beyond the Highway Capacity Manual Framework for Selecting Simulation Models in Traffic Operational Analyses
Authors: Elefteriadou Lily , Leonard John D. , List George , Lieu Henry , Thomas Michelle , Giguere Ron , Johnson Greer , Brewish Ra’id
Published: April 2007

Simulation is often used to address issues that cannot be effectively resolved using the Highway Capacity Manual (HCM) or other analytical procedures. However, guidelines are not available for appropriate application of simulation as a complement or substitute for HCM procedures. The purpose of this paper is threefold: ( a) to provide an overview of simulation models in a context consistent with facilities and situations addressed by the HCM, ( b) to present a framework for the appropriate selection of simulation models when procedures of the HCM are not adequate, and ( c) to provide brief examples demonstrating application of the proposed framework. The paper is divided into five sections. The first section presents simulation concepts and definitions. The second presents a suggested framework for application of simulation within an HCM context. The third and fourth sections apply this framework to the evaluation of uninterrupted- and interrupted-flow facilities, respectively. In these, appropriate application of the proposed framework for integration of simulation into an HCM-type analysis framework is presented. Last, the relationship between the methodological framework presented in this paper and the upcoming HCM 2000 is discussed.