bluuebunny/crossref_metadata_2025 huggingface dataset:
Three-Strand Cable Median Barrier in North Carolina: In-Service Evaluation
Authors: Hunter William W. , Richard Stewart J. , Eccles Kimberly A. , Huang Herman F. , Council Forrest M. , Harkey David L.
Published: April 2007

By using historical crash data, several regression-type models were developed with which to estimate the effects of the installation of cable median barrier on crash rates for several crash types while taking into account several other factors associated with variation in crash occurrences or crash rates. The data for these analyses consisted of counts of crashes of the various types for each section of North Carolina Interstate highway, along with the associated roadway characteristics, for 1990 through 1997. Certain roadway characteristics (in particular, traffic volume) changed from year to year as, of course, did the crash counts. The entire North Carolina Interstate system was taken as a reference population; a negative binomial error structure was assumed for many of the models, and the models contained specific effects for each crash year to account for various unmeasured effects that may vary from year to year (e.g., weather conditions). These models used the reference population to predict numbers of crashes on the cable sections. After cable barrier installation, none of these crashes occurred. In summary, these analyses indicate that several types of crashes (e.g., ran-off-road-left, hit-fixed-object) increased on the sections where cable median barrier was installed. However, these sections showed improved overall safety through fewer serious and fatal crashes as well as fewer head-on crashes. Overall severity index values were greatly reduced after cable barrier installation.
Selection of Roadside Safety Barrier Containment Level According to European Union Standards
Authors: Montella Alfonso
Published: April 2007

The new European Standards EN 1317-1/2 define the performance classes of road restraint systems and induce a growing interest for roadside safety. However, analytical procedures, like benefit-cost analysis, are not used in Europe for the selection of specific roadside safety features at specific locations or for the development of warrants, policies, and guidelines on a systemwide basis. A model for the selection of roadside safety barrier performance level according to European Union standards is presented. The new procedure is an encroachment-based benefit-cost analysis that takes into account the effective performance level of road safety barriers on the basis of a comparison between the real-world impact conditions and the impact conditions of the full-scale crash tests performed according to the European Committee for Standardization standards. The behavior of the safety barriers in relation to the impact conditions has been studied by performing nonlinear dynamic finite element analysis of collisions of heavy-goods vehicles against steel road safety barriers. As a result of the study, analytical relationships between a barrier’s containment capacity and impact conditions have been obtained. The expressions obtained allow one to evaluate the number of vehicles successfully redirected from the safety barriers in relation to the type of road, to the geometrical features of the road, to the traffic volume and composition, and to the safety barrier containment level. The model allows one to calculate the benefits arising from the greater number of vehicles redirected from safety barriers with greater level of performance and to compare roadside alternatives.
Near-Term Procedural Enhancements in Air Traffic Control
Authors: Cooper Wayne W. , Gordon Laurence M. , Hargroves Bradley T. , Maroney David R. , Spelman Joseph
Published: April 2007

As the National Airspace System (NAS) of the United States grows in usage and complexity, there is continuous improvement in the procedures that support it. Of particular interest are the improvements that can be made without acquiring new automation or systems. Fundamentally, these improvements are changes to the performance of operations that make better use of the tools and capabilities currently available to the users and service providers. These changes are collectively called “procedural enhancements.” The Federal Aviation Administration (FAA) has identified a number of procedural enhancements that can be implemented in the 1998–2002 time frame, which has been labeled the “near-term” time frame. Due to financial constraints, not all the enhancements can be implemented, so FAA has selected several that could yield efficiency benefits to the NAS. In partnership with FAA, MITRE’s Center for Advanced Aviation System Development (CAASD) is assisting with the implementation of several of these near-term procedural enhancements. These include lifting the 250-knot speed limit, improving North American Route Program transitions, reducing flow restrictions, and eliminating air traffic control preferred routes. Analysis and implementation of procedural enhancements by FAA and CAASD continue to assist system efficiency while new automation and tools are being procured.
Modeling Airside Airport Operations Using General-Purpose, Activity-Based, Discrete-Event Simulation Tools
Authors: Martinez Julio C. , Trani Antonio A. , Ioannou Photios G.
Published: April 2007

The application of activity-based simulation techniques to model runway operations at airports is described. The simulation tool used, STROBOSCOPE, is a discrete-event simulation system and programming language based on the three-phase activity scanning simulation paradigm. The model developed can be used as a tool to estimate runway capacity, delays, and double runway occupancy instances.
Quality Assurance Program for Work-Zone Traffic Control
Authors: Bryden James E. , Andrew Laurel B.
Published: April 2007

A quality assurance program was developed and implemented by the New York State Department of Transportation to manage work-zone traffic control on department projects. Using a standardized process, a team of experienced engineers inspects a large sample of projects across the state each year. Standard rating forms are completed to describe the temporary traffic control observed on each project. “Emphasis points,” which describe recurring areas of concern, are evaluated on each project, and a quality rating is assigned using a standardized six-point 0 to 5 scale to describe the overall condition and effectiveness of the project. Quality goals have been established both for average ratings for regional program areas and for individual projects. Implementation of this quality assurance program over the past 14 years has led to a substantial improvement in the quality of work-zone traffic control on New York State projects.
Evaluation of Supplementary Traffic Control Measures for Freeway Work-Zone Approaches
Authors: Sanford Bernhardt Kristen L. , Virkler Mark R. , Shaik Nawaz M.
Published: April 2007

Controlling traffic in work zones to improve safety continues to be a major concern for highway agencies. Three traffic control devices—white lane-drop arrows, the citizens band (CB) wizard alert system, and orange rumble strips—were tested for their effectiveness in improving merging and in reducing speed and speed variance at an Interstate highway work zone in Missouri. On the basis of the results of the study described, the lane-drop arrows, CB message, and rumble strips can be expected to promote some increases in early merging and some decreases in mean speeds of vehicles approaching an Interstate highway work zone with a lane drop. Effects of all three devices on speed variance are inconclusive. However, because of the difficulty in summarizing across the many variables involved (day/night/dawn/dusk, open/closed lane, vehicle class, etc.), it is recommended that anyone considering the use of the devices examine the full report.
Use of Mobile Video Data Collection Equipment to Investigate Winter Weather Vehicle Speeds
Authors: Knapp Keith K. , Smithson Leland D.
Published: April 2007

Mobile video data collection equipment was used to collect data and determine traffic flow and roadway surface conditions during seven winter weather events. Driver visibility was estimated manually. The use of the mobile video data collection equipment in this research and some concerns related to its use during winter weather are discussed. The characteristics of the data are summarized, and the results of a multiple regression statistical analysis presented. Winter weather data were collected and summarized by 15-min time periods. The data included traffic volumes, vehicle speeds, vehicle gaps or headways, visibility, and roadway snow cover. The average winter weather vehicle speed was significantly lower than normal, and multiple regression indicated a relationship among the average off-peak winter weather vehicle speed, the square of hourly volume, visibility, and roadway snow cover. The traffic volume variable in this model was believed to be a surrogate for weather data not collected. The model predicts that visibility below 0.4 km (0.25 mi) and snow cover on the roadway lanes may reduce average off-peak winter weather vehicle speeds by approximately 6.3 and 11.7 km/h (3.9 and 7.3 mph), respectively. It was concluded that the collection of traffic flow and roadway surface data during winter weather events requires the seamless integration, planning, and calibration of a partially video-based automated permanent or semipermanent information system. The ability to assess, quantify, and communicate the potential vehicle speed effects of winter weather could assist drivers with travel decisions and public-sector workers with maintenance decisions.
Transferability of Models That Estimate Crashes as a Function of Access Management
Authors: Miller John S. , Hoel Lester A. , Kim Sangjun , Drummond Kendall P.
Published: April 2007

Access management can improve safety or operations but may reduce accessibility for adjacent residences or businesses, causing conflict between the needs of local and through traffic and resulting in access management decisions being challenged by the public. Accordingly, transportation administrators require assurance regarding the accuracy of projected safety impacts of access management decisions. Several existing mathematical models quantify these impacts for selected access management techniques. Since new models require substantial resources to construct, it is prudent to investigate the extent to which existing models can be applied in other locations. A study of mathematical models that predict the number of crashes that will result as a function of signal spacing, median treatments, unsignalized driveways, and other key variables is reported. The study compared five models using a 10-year set of geometric, operational, and crash data for three case study corridors. The crash-prediction ability of these models was assessed using traffic flow data other than the data set used to construct the models. Because some of the models were not developed for application elsewhere or were intended to be used only with a site-specific adjustment, the error percentages indicate the extent to which the models are transferable, but they do not constitute a critique of the previous research. With no site-specific adjustment, the accuracy of the models ranges from an average error of 34 to a few hundred percent. With simple site-specific adjustments, errors are in the range of 27 to 29 percent. Substantially less effort is required for these site-specific adjustments than would be required to create a new mathematical model. Recommendations were developed for using these models in practice, understanding their limitations, and interpreting their sensitivity to key inputs, data needs, and computational requirements.
Simulation of Road Crashes by Use of Systems Dynamics
Authors: Mehmood Arif , Saccomanno Frank , Hellinga Bruce
Published: April 2007

The framework of a systems dynamics model (SDM) is presented for simulating road crashes. For the purpose of illustration, the model is applied to two-vehicle rear-end crashes where both vehicles are assumed to be traveling in the same lane. The crash situation results from the introduction of some obstruction along the pathway, which causes drivers to adjust their speeds and separation distances. SDM extends the features of classical car-following theory in combination with crash avoidance models. Preliminary results are discussed. The SDM provides a number of useful insights into the complex process that gives rise to rear-end crashes for an assumed transportation scenario. These insights can serve to guide the development of effective safety countermeasures for reducing rear-end crashes. The potential relevance of the model for other crash situations is also discussed.
Longitudinal Analysis of Fatal Run-Off-Road Crashes, 1975 to 1997
Authors: McGinnis Richard G. , Davis Matthew J. , Hathaway Eric A.
Published: April 2007

Data from the Fatality Analysis Reporting System and the National Personal Transportation Studies were used to study run-off-road (ROR) fatal crashes over the period 1975–1997. Longitudinal trends in roadside crashes were analyzed to see how driver characteristics such as gender, age, and alcohol usage relate to ROR crashes. ROR crash rates, adjusted for driving exposure, have decreased 40 percent for male and female drivers since peaking in 1980. The greatest improvement has occurred at night on rural and urban non-Interstate highways. Young drivers, male drivers, drivers over 70 years of age, utility vehicles, rollovers, and alcohol pose special challenges for roadside safety improvements efforts. Male drivers have higher ROR crash rates than females, even after adjusting for driving exposure. Males aged 20 to 24 have ROR crash rates 3.3 times those of females of the same age. Using ROR crash rates for female drivers aged 40 to 49 as a base, ROR rates for teenage males are 20 times as high and for teenage females 9 times as high. For drivers aged 70 and older, these ratios are 4.5 for males and 4.0 for females. Alcohol involvement in ROR crashes is nearly 50 percent for male drivers aged 20 to 39 and is more than 50 percent for all drivers during dark conditions. From 1975 to 1997 the number of utility vehicles involved in ROR crashes increased nearly 600 percent. Seventy percent of fatal ROR crashes with utility vehicles involve a rollover. Rollovers rates for vans and pickups involved in fatal ROR crashes are nearly five times those for non-ROR crashes.
Value of Arizona’s State Highway System: Corporate-Style Financial Analysis
Authors: Mansour-Moysey Nadia , Semmens John
Published: April 2007

Government agencies and private-sector corporations tend to approach financial reporting in different ways. Presentation of government-agency financial information by corporate-style reporting could accomplish two specific goals. First, it might provide a more economically sound picture of the financial status of governmental undertakings. Second, this approach may allow a better comparison of the net profit and return on investment that is generated from the state highway system and the true value of the highways to be made. The results of an analysis showed that Arizona’s state highways are at best a “breakeven” proposition that does not allow for traffic growth or other contingencies. The amount that is charged to the users of the state highways is approximately 2.5 cents/vehicle-km (4 cents/vehicle-mi), whereas the estimated minimum value of the combined vehicle-highway system to its users is in excess of 18.6 cents/vehicle-km (30 cents/vehicle-mi). This implies that fees could be increased to allow the state highway system to generate an appropriate return on investment without significantly depressing usage. The current system of pricing of highway resources is inefficient and may not generate monies sufficient to replace deteriorating roadways and to build additional capacity as demand increases. Implementation of a differential pricing strategy (for example, electronic tolling) would provide a more economic and socially efficient and equitable way to charge for transportation services. A corporate-style analysis allows an efficient price for these services to be determined, and electronic tolling provides an efficient method of collection of these revenues.
Static Versus Demand-Sensitive Models and Estimation of Second–Best Cordon Tolls: An Exercise for Eight English Towns
Authors: Santos Georgina , Newbery David , Rojey Laurent
Published: April 2007

The static economic model of traffic congestion suggests that external costs can be internalized, with link-specific congestion charges equal to the externality at the efficient level of traffic. Such a scheme remains theoretical. Feasible cordon-toll schemes were considered for eight English towns, and optimal tolls were estimated. These are lower than theoretical computations suggest, as only central-area traffic is tolled, shifting traffic from congested to uncongested areas. Cordon tolls seem reasonably robust and error tolerant in the demand elasticity estimates, provided that these (and the resulting tolls) are pitched low.
Creating a New Century of Transit Opportunity: Strategic Planning for Transit
Authors: Lieberman William , Schumacher Dave , Hoffman Alan , Wornum Christopher
Published: April 2007

Like most other transit agencies in the United States, the Metropolitan Transit Development Board (MTDB) in San Diego, California, had never developed a strategic plan. Nevertheless, such plans are necessary for public agencies to better understand their present and potential roles in shaping the future of their respective metropolitan areas. MTDB conducted a review of other transit systems’ strategic plans, particularly the strategic plans of transit systems overseas, to determine the characteristics of the most successful planning processes. It then embarked on an extensive market survey to learn why residents in its service area made the travel choices that they did. These proved to defy common stereotypes and led to the segmentation of the market into six discrete groups of travelers. By understanding the needs of each market segment and their respective travel patterns, the agency was then able to craft four service strategies aimed at appealing to the largest cross section of the region’s residents. The MTDB board of directors was then presented with four alternative scenarios describing transit’s potential role in the region over the next 20 years. Each scenario was associated with a different level of transit financing and influence over land use patterns and transit priority. By using the market research information, alternative transit concept plans were developed for each scenario and overall funding needs were identified. The process was completed in October 2000 with MTDB’s selection of the most ambitious of the four scenarios, Transit First. Given the positive support from business, community, and environmental groups, this action signals a paradigm shift in the region that public transportation can and should play an increased role in meeting the region’s mobility needs over the next 20 years.
Light Rail Proximity: Benefit or Detriment in the Case of Santa Clara County, California?
Authors: Weinberger Rachel R.
Published: April 2007

When the public sector sponsors projects to promote general welfare, disproportionate benefits or disproportionate burdens often fall on individuals. In Santa Clara County, California, private property owners sued the county for damages, claiming a burden due to the existence of light rail transit (LRT). By looking at rental rates for commercial property, the present research tests several hedonic specifications to determine what effect, if any, LRT has on proximate property values. It also compares transit accessibility with highway accessibility as determinants of rent. An understanding of this effect allows the county to make informed decisions in its defense against the suits brought and allows other government entities to make informed decisions with respect to the building of future LRT systems. The results indicate that, when controlling for other factors, properties that lie within 0.8 km (0.5 mi) of a light rail station command a higher lease rate than other properties in the county. When controlling for highway access, the rail proximity benefit was maintained, and it was shown that highway coverage in the county is so dense that there are no particular locational advantages associated with highway coverage.
Comparison of TRANSIMS and CORSIM Traffic Signal Simulation Modules
Authors: Rilett L. R. , Kim Kyu-Ok
Published: April 2007

The microsimulation-based Transportation Analysis and Simulation System (TRANSIMS), which represents the next generation of travel forecasting techniques, was designed to model the transportation system of a metropolitan area at an individual traveler’s level. Although the default model parameters in the TRANSIMS traffic signal logic were calibrated to the macroscopic flow relationships contained within the Highway Capacity Manual, to date there has been no research on the traffic signal characteristics of TRANSIMS using empirical data. The TRANSIMS traffic signal logic is examined with an emphasis on how well it could replicate diamond interchange operations. A diamond interchange network was coded into TRANSIMS, and the simulation results were compared with both empirical observations and CORSIM results. It was found that TRANSIMS logic could model the operation of a diamond interchange with respect to offset, cycle length, traffic demand, and signal spacing.
Configuration Management in Transportation Management Systems: Evaluation of Need
Authors: Smith Brian L. , Smith Bayne E.
Published: April 2007

Configuration management, a process developed to control change in complex information technology–based systems, has attracted an increasing amount of attention from the transportation engineering community. As the intelligent transportation systems program accelerates and transportation departments develop and operate increasingly complex transportation management systems, the need for configuration management grows. In this research effort the need for configuration management within transportation management systems is examined by exploring the foundations of configuration management, analyzing the key functions of transportation management, surveying transportation officials, and conducting a case study to examine the configuration management process used by the Georgia Department of Transportation.
Multistage Stochastic System Optimum Dynamic Traffic Assignment Program with Recourse for Incident Traffic Management
Authors: Sawaya Omar B. , Doan Dung L. , Ziliaskopoulos Athanasios K. , Fourer Robert
Published: April 2007

Robust real-time traffic management methodologies are needed to respond to freeway congestion caused by unexpected incidents. A multistage stochastic mathematical model with recourse is introduced to compute and disseminate real-time traffic control actions, which account for system uncertainties such as demand variation and incident severity. The benefits include the provision of a priori robust traffic control actions that are ideal under all circumstances of system uncertainties across all considered time periods, with significant reduction in the online computational effort. As a result, more insights on the relationship between traffic control actions and network properties across time periods are obtained.
Freeway Crash Timeline Characteristics and Uses
Authors: Drakopoulos Alex , Shrestha Mahesh , Örnek Ertan
Published: April 2007

Timeline information for freeway crashes was extracted using 10,589 crashes, 2,816 of which were matched with enforcement agency dispatch records and 320 of which were matched with ambulance dispatch records. The average time between when a crash occurred and when the crash scene was cleared was 52.2 min. The enforcement agency was notified 3.4 min after the crash, and the first responding officer arrived at the crash scene 6.0 min later. The ambulance dispatcher was notified 5.1 min after the first responding officer arrived at the scene, and the first ambulance arrived at the scene 7.5 min later, remained at the scene 20.9 min, and arrived at the hospital 10.9 min after it left the crash scene. Enforcement agency notification and response times were not affected by crash and environmental factors; however, enforcement agency on-scene time (representing 80 percent of crash duration) was statistically related to crash type, crash severity, need for emergency medical services transport, air bag deployment, light condition, manner of collision, road condition (presence of precipitation), number of injuries, number of involved vehicles, need for towing services, and extent of vehicle damage. The shortest crash durations were associated with two-vehicle crashes, crashes involving property damage only, and crashes involving vehicles able to drive away. The longest crash durations were those involving very severe vehicle damage, occupant medical transport, an overturned vehicle, and those occurring at night.
Vision-Based Stop Sign Detection and Recognition System for Intelligent Vehicles
Authors: Liu Henry X. , Ran Bin
Published: April 2007

The traffic sign detection and recognition system is an essential module of the driver warning and assistance system. A vision-based stop sign detection and recognition system is presented here. This system has two main modules: detection and recognition. In the detection module, the color thresholding in hue, saturation, and value color space is used to segment the image. The features of the traffic sign are investigated and used to detect potential objects. For the recognition module, one neural network is trained to perform the classification and another one is trained to perform the validation. Joint use of classification and validation networks can reduce the rate of false positives. The reliability demonstrated by the proposed algorithm suggests that this system could be a part of an integrated driver warning and assistance system based on computer vision technologies.
Modeling Effects of Driver Control Assistance Systems on Traffic
Authors: VanderWerf Joel , Shladover Steven , Kourjanskaia Natalia , Miller Mark , Krishnan Hariharan
Published: April 2007

A set of mathematical models is defined to predict the effects of emerging driver control assistance systems such as adaptive cruise control (ACC) on traffic flow dynamics and capacity. It is important to understand these effects in order to ensure that ACC systems are implemented in ways that improve, rather than degrade, traffic conditions. Existing traffic models were not designed for, and are not suitable for, this purpose, so it has been necessary to develop a new family of simulation models incorporating the key elements of driver behavior and control system design that will affect traffic flow dynamics and capacity. Example outputs from simulation validation test cases are illustrated and explained to show that the models are producing reasonable results.
Potential for Private-Sector Road Maintenance in Developing Countries: Case Studies
Authors: Parkman Christopher C. , Madelin Keith B. , Robinson Richard
Published: April 2007

Examined are the different approaches adopted worldwide for involving the private sector in road maintenance, and competing claims for public- and private-sector involvement are assessed. Literature was surveyed, and case studies were carried out in Colombia, Ghana, and the United Kingdom to provide practical examples of a range of countries, conditions, and experiences. The aim was to give particular attention to the needs of low-income situations, and cases in the United Kingdom provided a baseline industrial country comparison. General findings indicate that in many countries the private sector is carrying out road maintenance duties. However, it has been difficult to identify objective, quantitative conclusions about cost savings from this approach because private-sector involvement is always concurrent with changes in other aspects of road management. Key issues that emerge are the needs for adequate funding, for separation of the client and supplier roles as a means of improving effectiveness and efficiency, and for the use of competition rather than simple emphasis on private-sector delivery. A partnering approach also provides benefits. A stepwise transition to outsourcing may offer a more pragmatic solution than the rapid and radical change to private-sector use that many developing countries have adopted. Above all, management of road administrations must be improved, irrespective of the mechanism of service delivery. Accomplishing this task may require both organizational and cultural changes.
Cost-Benefit Highway Pavement Maintenance
Authors: Najafi Fazil T. , Valerie Paredes B.
Published: April 2007

Many methods used in highway maintenance plans are complex, and agencies often exclude components related to user costs in the work zone (such as vehicle operating costs, delay costs, and crash costs) when making project improvement decisions. Highway users are taxpayers, and considering the user costs in project rehabilitation, resurfacing, and reconstruction provides the greatest return on project tax dollars spent. A simple five-step procedure that includes user work zone costs in the selection of highway maintenance projects has been developed and applied to the city of Gainesville, Florida, roadway improvement network projects: (1) collect distress data, (2) prepare inventory forms for the roadway networks, (3) prepare a maintenance cost plan, (4) prepare priority rankings for project improvements, and (5) select and implement project rehabilitation on the basis of priority ranking. These five steps assist highway agencies (public works officials and highway engineers) in simplifying maintenance programs in light of limited funding and help agencies choose priorities for highway maintenance funding for projects.
Potential of Using Stone Matrix Asphalt for Thin Overlays
Authors: Allen Cooley L. , Ray Brown E.
Published: April 2007

Stone matrix asphalt (SMA) has been used in the United States since 1991. To date, almost all of the SMA mixes have had a nominal maximum aggregate size (NMAS) of either 12.5 or 19.0 mm. These two NMASs have been predominant because they conform to information obtained from European experiences with SMA. However, a “fine” SMA mix (for the purpose of this study defined as having an NMAS of 4.75 or 9.5 mm) could be beneficial because it could be placed in thinner lifts and should be more workable. A study was conducted to evaluate the potential of designing fine SMAs and to compare these fine SMAs with more conventional SMA mixes (larger NMASs). Study data indicate that these fine SMAs could be successfully designed to have stone-on-stone contact. Rut testing with the Asphalt Pavement Analyzer confirmed that the designed fine SMA mixes were rut resistant. Permeability testing indicated that these fine SMA mixes are less permeable than conventional SMA mixes at similar void levels and thus should be more durable. Based on information from this study, fine SMAs are a viable option for thin overlays.
Maintenance of Concrete Bridges
Authors: Sprinkel Michael
Published: April 2007

The principal reason concrete bridges deteriorate is that the reinforcement is damaged by chloride-induced corrosion. Effective maintenance, for the most part, involves activities designed to keep chlorides away from the reinforcement. Six maintenance activities help accomplish this goal: flushing debris and chlorides from decks and pier caps annually, repairing and sealing joints, sealing cracks, patching potholes, replacing the membrane if replacing an asphalt overlay, and installing low-permeability overlays.
Partnership for a New Generation of Vehicles’ Fuel Economy Goal: Evaluation of Trade-Offs Along the Path
Authors: Santini Danilo J. , Vyas Anant D. , Anderson John L. , An Feng
Published: April 2007

The Partnership for a New Generation of Vehicles (PNGV), a government and industry joint initiative, has established a goal of tripling the fuel economy of a midsize sedan. A series of modeling experiments was conducted to examine the relative effectiveness of various technical steps cumulatively accomplishing this goal. A composite 1995 midsize sedan was sequentially modified, resulting in 21 different vehicles, each with selectively singularly altered candidate technical modifications that are evaluated with respect to their effectiveness for increasing fuel economy. The candidate technical modifications included manual transmission; reduced acceleration requirement; reduced frontal area and coefficient of drag; low-resistance tires; lightweight material; fuel-efficient, turbocharged, direct-injection diesel engine; hybridizing to a parallel configuration; and lower grade-climbing requirements. The study design is discussed, and simulated fuel economy gain for each step is presented. The modeling exercise also estimated that it is possible to reach the triplefuel-economy goal with these modifications.
Recent Validation Efforts for a Comprehensive Modal Emissions Model
Authors: Barth Matthew , Malcolm Carrie , Younglove Theodore , Hill Nicole
Published: April 2007

Mobile source emissions estimation techniques play a critical role for regional planning and development of emission control strategies. The primary models for mobile source emissions estimation have been the U.S. Environmental Protection Agency’s MOBILE model and the California Air Resources Board’s EMFAC model. These models work well for large regional areas but are not as well suited for “microscale” evaluation. Over the last several years, the College of Engineering–Center for Environmental Research and Technology (CE-CERT) has been evaluating in-use, light-duty vehicles as part of NCHRP Project 25-11, resulting in the development of a Comprehensive Modal Emissions Model (CMEM). An essential part of any model development process is validating the model. Various validation techniques have been applied to CMEM. This paper describes some of the latest validation work carried out in comparing CMEM results to independent emission testing results (independent in both vehicles and driving cycles). Further, CMEM has been compared with the latest versions of EMFAC and MOBILE. In general, compared with the independent emission measurements, CMEM predicts well. It has been found that CMEM is consistent with MOBILE and EMFAC at low to medium speeds. Greater deviations were found at very low speeds and very high speeds. At high speeds, CMEM tends to predict higher hydrocarbon (HC) emissions and lower oxides of nitrogen (NOx) emissions. At the very low speeds, CMEM tends to predict lower than EMFAC and MOBILE for all emissions. These comparisons are part of an ongoing validation process for development of CMEM.
Modeling Soak-Time Distribution of Trips for Mobile Source Emissions Forecasting: Techniques and Applications
Authors: Nair Harikesh S. , Bhat Chandra R. , Kelly Ryan J.
Published: April 2007

The soak time of vehicle trip starts is defined as the duration of time in which the vehicle’s engine is not operating and that precedes a successful vehicle start. The temporal distribution of the soak time in an area is an important determinant of areawide mobile source emissions. In this study, a methodology for modeling soak-time durations is formulated and implemented. The methodology involves estimation of models using vehicle trip data from household travel surveys and supplementary zonal demographic and land use data. The effectiveness of the methodology lies in its easy application at the traffic zonal level within a metropolitan region to obtain zone-specific soak-time distributions by time of day and origin activity purpose. The methodology is applied to estimate soak-time duration models for the Dallas–Fort Worth area of Texas.
Design and Administration of Accelerated Vehicle Retirement Programs in North America and Abroad
Authors: Dill Jennifer
Published: April 2007

Several countries, states, and local agencies have debated and many have adopted voluntary accelerated vehicle retirement (VAVR) programs. The basic premise behind a VAVR program is to reduce emissions by taking an older, more polluting vehicle off the road before its owner would otherwise scrap it. A descriptive overview of the components of past and current VAVR programs in the United States and Canada is provided, with some comparisons with programs abroad. VAVR programs in North America fall into two broad categories—programs that generate “mobile source emission-reduction credits” that can be used to comply with other air quality regulations, and programs in which emission reductions are “used” only to help meet air quality standards. Incentives in the U.S. programs range from $400 to $1,000. The programs include a variety of criteria, including ownership and operability standards, to help ensure that emission reductions are real.
Emissions Inventory Analysis of Mobile Source Air Pollution in Tel Aviv, Israel
Authors: Newmark Gregory L.
Published: April 2007

Air pollution from motor vehicles is an acute urban problem in many rapidly developing countries. Air quality monitoring in Israel has both demonstrated the severity of the problem in Israel and identified transportation emissions to be the major contributor to its etiology. Currently, a major concern is the high level of nitrogen oxide nonattainment in Tel Aviv. Thousands of nitrogen oxide violations are recorded there every year. This pollution both affects the local population and provides the driving factor behind the ozone formation downwind in Jerusalem and the West Bank. This paper presents the innovative effort to compile varying streams of data to create an urban vehicle emissions inventory for the city of Tel Aviv. The inventory provides an excellent understanding of the relative contributions of four air pollutants between and within each vehicle cluster. The major findings are that, of total urban vehicle emissions, cars purchased before 1993, when catalytic converters became mandatory, produce 60 percent of carbon monoxide and 55 percent of hydrocarbon emissions. City buses produce 67 percent of nitrogen oxide and 39 percent of particulate matter emissions. Trucks and taxis each contribute about an eighth of total nitrogen oxide and a quarter of total particulate matter emissions. The major policy direction suggested by these findings is diesel fleet vehicle mitigation. In short, an effective approach is presented for industrializing nations to quickly assess their mobile pollution sources, and the foundation data are compiled for further mobilesource analyses in Israel.
Design Factors That Affect Driver Speed on Suburban Streets
Authors: Fitzpatrick Kay , Carlson Paul , Brewer Marcus , Wooldridge Mark
Published: April 2007

Many roadway factors have an effect on driver behavior. Geometric, roadside, and traffic control device variables that may affect driver behavior on four-lane suburban arterials were investigated. Traffic signals and traffic volume were considered within the study site selection and data collection criteria and, therefore, were not included in the analysis. Regression techniques were used to determine how selected variables affect operating speed on horizontal curves and straight sections. When all variables were considered, posted speed limit was the most significant variable for both curves and straight sections. Other significant variables for curve sections were deflection angle and access density class. In another series of analyses performed without using posted speed limit, only lane width was a significant variable for straight sections, but median presence and roadside development were significant for curve sections. The analysis that included posted speed limit, however, produced stronger relationships between speed and significant variables than did the analysis that excluded posted speed limit.
Operating Speed Prediction on Crest Vertical Curves of Rural Two-Lane Highways in Nebraska
Authors: Jessen Daniel R. , Schurr Karen S. , McCoy Patrick T. , Pesti Geza , Huff Ryan R.
Published: April 2007

Since the repeal of the National Maximum Speed Limit by the U.S. Congress, individual states have been modifying existing speed limits on state and federal highways. Increases in speed limits have caused the inferred design speeds of many crest vertical curves along two-lane rural highways to be less than the posted and operating speeds according to accepted national guidelines. Past research has found that rate of curvature and inferred design speed can be used to predict operating speeds on crest vertical curves. Crest vertical curve, roadway, traffic, and speed characteristic data are included to determine the features that influence the speeds on crest vertical curves. Speed data were collected on 70 crest vertical curves across Nebraska. Multiple linear regressions were included to determine the crest vertical curve, roadway, traffic, and speed characteristics that affect speeds on crest vertical curvature. The posted speed of the highway was found to have the most influence on the operating speed. The inferred design speed of the vertical curves was not a significant factor.
Pattern Recognition in Complex Activity Travel Patterns: Comparison of Euclidean Distance, Signal-Processing Theoretical, and Multidimensional Sequence Alignment Methods
Authors: Joh Chang-Hyeon , Arentze Theo , Timmermans Harry
Published: April 2007

The application of a multidimensional sequence alignment method for classifying activity travel patterns is reported. The method was developed as an alternative to the existing classification methods suggested in the transportation literature. The relevance of the multidimensional sequence alignment method is derived from the fact that structural information (both interdependency and sequential relationships) embedded in activity travel patterns is taken into account—a property not shared with existing classification methods. The performance of the multidimensional sequence alignment method is compared with several other methods (Euclidean distance and signal processing) that have been used in activity analysis in the past.
Within-Household Allocation of Travel: Case of Upper Austria
Authors: Simma A. , Axhausen K. W.
Published: April 2007

The interactions between the heads of a household with regard to their out-of-home activities and travel behavior in Upper Austria are investigated. To answer the research questions, a structural equation model is developed. The data used in the modeling process are from an extensive travel diary of over 100,000 households in Upper Austria combined with extensive data on land use and local economic activities. The main result of the model is that sex-specific division of labor in nuclear families is still common. If women are working, the number of their maintenance trips is reduced, but this reduction is not compensated for by men. Normally, female employment is connected with a decrease in the number of other female activities and an increase in car ownership and traveled distances. In addition, the model shows that out-of-home activities often are carried out together. The number of reachable infrastructure facilities is the most important spatial variable, whereby good access promotes the reduction of car-ownership and traveled distances.
Timetable-Based Transit Assignment Using Branch and Bound Techniques
Authors: Friedrich Markus , Hofsaess Ingmar , Wekeck Steffen
Published: April 2007

Transit assignment procedures need to reflect the constraints imposed by line routes and timetables. They require specific search algorithms that consider transfers between transit lines with their precise transfer times. Such an assignment procedure is presented for transit networks using a timetable-based search algorithm. In contrast to existing timetable-based search methods employing a shortest-path algorithm, the described procedure constructs connections using branch and bound techniques. This approach significantly reduces computing time, thus facilitating the use of timetable-based assignment for large networks. At the same time, it produces better results in cases where slow but cheap or direct connections compete with fast connections that are more expensive or require transfers.
Telecommuting Implications for Travel Behavior: Case Studies from Minnesota
Authors: Wells Kimberly , Douma Frank , Loimer Hannes , Olson Laura , Pansing Cynthia
Published: April 2007

Case studies of two telecommuting programs were conducted as part of a larger research effort devoted to examining the implications of telecommunications for Minnesota transportation and community development. Data were collected in a large private high-technology firm and in a public agency located in the Minneapolis–St. Paul area. A multiple method design was employed including a cross-section survey of nontelecommuting employees; a census survey of telecommuters; and in-depth interviews with telecommuters, their coworkers, and their supervisors. Analyses were conducted to explore the relationship between telecommuting and travel behavior and the potential effects of travel outcomes for community systems. Results indicate that telecommuting implementation strategies differ within and between organizations, and these differing approaches appear to moderate the relationship between telecommuting and complex travel behaviors, such as local errand running and trip chaining. Additional findings concur with those of other studies, and the difficulty of the commute is highlighted as a primary factor in understanding the choice to telecommute and its impact on travel behavior.
Modeling Passenger Waiting Time for Intermodal Transit Stations
Authors: Jason Chang S. K. , Hsu Chun-Lin
Published: April 2007

A mathematical model is developed to analyze the passenger waiting time of an intercity transit station with feeder bus services. Intercity transit system is characterized by its comparatively long headway and fixed schedules. Thus, the behavior of passengers of intercity transit station is significantly different from the behavior of passengers of urban bus systems. If the urban bus system is always considered as a major feeder system for the intercity transit, passenger waiting time and related behaviors of the intercity transit station should be influenced by the reliability of the feeder bus services. The results provide planners with an analytic model for accurately quantifying the relations between passenger waiting time of intercity transit system (e.g., high-speed rail) and the reliability of feeder bus services.
Seattle Intelligent Transportation System Information Backbone
Authors: Collura John , Chang James , Carter Mark
Published: April 2007

This case study involved the review of the advanced traveler information system (ATIS) and advanced traffic management system (ATMS) and the use of the information backbone (I2B) component of the intelligent transportation system of the Seattle Metropolitan Model Deployment Initiative. Through a survey of documents and other material combined with interviews of key participants, the nature of any increased benefits or reduced costs associated with ATIS and ATMS integration resulting from the I2B was examined. The results suggest that the distributed nature of the I2B provided for the coordination of responsibility among multiple information contributors and processors as well as geographic flexibility. The open nature of participation was also cited as a factor in making connection to the I2B a relatively easy matter since software tools for interfacing are provided. For contributors, the I2B has provided the ability to distribute information via a single access method, thereby reducing support effort. Processors can gain easier access to existing information in addition to being able to develop composite information from multiple sources. Comparison of costs between the I2B and alternative information system designs was difficult because of the differences in functionality provided. However, it appears likely that costs are shifted from the information contributors to the processors, who gain from the addition and realization of value in the marketplace.