bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Changing Traffic Characteristics and Environmental Conditions on Flexible Pavements
Authors: Zhang Zhanmin , Leidy Joseph P. , Kawa Izydor , Ronald Hudson W.
Published: April 2007

Although the trend for the next generation of pavement design methods is shifting to mechanistic design, the use of design methods based on the AASHO road test results is still the current design practice in Texas and some other states. Critical to these design methods are the AASHTO load equivalency factors (LEFs), which are used to convert the mixed traffic axle loads into standard 18-kip (80.1-kN) equivalent single-axle loads. Several studies have been conducted on the subject of load equivalency for pavement design and analysis. However, there remain uncertainties related to various issues of load equivalency. Over the years, the composition and characteristics of traffic using Texas highways have been changing. The North American Free Trade Agreement has accelerated such changes in that more trucks, primarily moving among mid-western states, Texas, and Mexico, are traveling on Texas highways. In addition, the original AASHO road test was conducted at a site with environmental conditions significantly different from the environmental conditions in Texas. It is therefore critical to understand fully the impact of such changing traffic characteristics and environmental conditions on pavements in Texas. Presented is the methodology used to analyze the impact of these factors on the AASHTO LEFs.
Construction and Performance of Fly Ash-Stabilized Cold In-Place Recycled Asphalt Pavement in Wisconsin
Authors: Crovetti James A.
Published: April 2007

Cold in-place recycling (CIR) is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In recent years, increased emphasis has been placed on incorporating stabilizers into the CIR materials to improve the structural capacity of the CIR base layer. This improvement can serve to increase the performance life of the completed pavement or to allow for a reduced hot-mix asphalt (HMA) surface thickness. The city of Mequon, Wisconsin, included asphalt emulsion and fly ash CIR stabilization over a portion of its CIR projects in 1997. Presented are the findings relating to the constructability of the fly ash–stabilized CIR pavement as well as performance trends for the CIR pavements based on distress and deflection testing results. CIR is a common rehabilitation practice used in Wisconsin to improve the ride quality and structural capacity of deteriorated asphalt pavements. In one type of CIR application, existing HMA layers are pulverized, graded, and compacted, then used as a base layer for a new HMA surface. The pulverization process is completed to provide uniformity of support to the HMA surface and to significantly reduce or eliminate the occurrence of reflection cracking of the HMA surface. In most CIR applications, pulverization is completed through the full thickness of the existing HMA layers, as well as through the top 25 to 50 mm of aggregate base. Penetration into unbound aggregate base materials aids in cooling of the bits on the pulverizer mandrel. After pulverization, graders typically are used to spread the materials to the desired width and shape. Compaction is achieved by using vibrating steel drum and pneumatic-tire rollers. The moisture content of the CIR materials is adjusted, as necessary, by surface spraying from a water tanker truck.
Pavement Rehabilitation Selection Based on Mechanistic Analysis and Field Diagnosis of Falling Weight Deflectometer Data: Virginia Experience
Authors: Zaghloul Sameh , Elfino Mohamed
Published: April 2007

The effectiveness of using the field diagnosis and falling weight deflectometer (FWD) mechanistic analysis in reducing a 65-km (40-mi) segment of asphalt pavement to project level segments is discussed, along with selecting a cost-effective rehabilitation strategy. A mechanistic-based analysis was performed on the deflection basins measured from I-85 in Virginia to backcalculate the layer moduli. The 65-km segment was divided into structurally homogeneous sections based on the back-calculated layer moduli. The data of each homogeneous section were analyzed further to assess the in situ structural capacity, to identify weak layers, to estimate the remaining structural life, and to determine the current and future rehabilitation needs. It was found that some sections have almost no remaining structural life, and others have remaining structural life of more than 10 years. A comparison was made between the FWD–field diagnosis rehabilitation program and a visual inspection rehabilitation program. Results of the comparison indicated that the visual inspection rehabilitation program resulted in selecting thicker overlays for some of the project sections (overdesigned) and thinner overlays for the other sections (underdesigned). It is estimated that the difference between the FWD–field diagnosis rehabilitation program and the visual inspection rehabilitation program for the overdesigned sections is in the range of 45 percent of the construction cost (savings). Life-cycle cost analysis (LCCA) was performed to quantify the difference between the two rehabilitation programs for the underdesigned sections. Results of the LCCA indicated that the FWD–field diagnosis rehabilitation program would result in 26 percent and 42 percent reduction in the construction cost and user delay cost, respectively.
Zigzagging of Bus Routes: An Analytical Approach
Authors: Kho Seung-Young
Published: April 2007

Bus transit routing schemes are analyzed for riders outside a major transit corridor. Two routing schemes are considered—no zigzagging and zigzagging. In the no-zigzagging scheme, the route runs along a demand corridor without detouring to pick up outlying riders, who must first access the corridor to be picked up. In the zigzagging scheme, the bus detours to pick up distant riders and then returns to the corridor to continue on to the final destination. Analytical cost models for nozigzagging and zigzagging bus routing schemes are developed. Solutions for zigzagging conditions are derived, and some important concepts, practical implications, and useful results are presented through some simplifications. Also, a practical analysis of several access modes is presented. Depending on the location and number of out-of-corridor passengers, zigzagging can be an efficient routing scheme. Zigzagging is especially efficient in the outlying ridership areas if the number of passengers already on board is low compared with the number of outlying passengers requesting corridor service.
Traction Performance of Transit and Paratransit Vehicles in Winter
Authors: Raad Lutfi , John Lu Jian
Published: April 2007

The traction performance of transit and paratransit vehicles during the winter is an important factor in public transportation system operations. Vehicle traction forces are significantly reduced on snowy or icy surfaces, specifically during stopping, starting, cornering, and hill climbing. Reduced traction increases stopping distances and decreases controllability when a vehicle stops in an emergency situation. This study evaluated the traction performance of transit and paratransit vehicles on snowy and icy surfaces. Field tests were conducted in Fairbanks, Alaska, using three types of vehicles—a 41-passenger transit bus, a 32-passenger transit bus, and a 9-passenger paratransit vehicle. Each vehicle was tested for different combinations of tire types, including highway tires, snow tires, studded-siped tires, highway three-rib tires, all-season tires, and snow-siped tires. Tests of winter traction performance evaluated stopping distance, starting traction, hill climbing, cornering, and controllability. For similar tire combinations and surface conditions, the tested transit and paratransit vehicles had different traction performance. Results indicate that winter traction performance is significantly influenced by vehicle type, tire combination, and road surface (compacted snow or ice). Research findings and recommendations for tire combinations best suited for winter traction are presented.
Development of Florida’s Transit Level-of-Service Indicator
Authors: Ryus Paul , Ausman Jon , Teaf Daniel , Cooper Marc , Knoblauch Mark
Published: April 2007

Transit availability—the opportunity to use transit service at a particular location—is a key determinant in transit use. If transit service is unavailable near a potential passenger’s origin and destination, it is not a viable travel option. The Florida Department of Transportation’s transit level-of-service (TLOS) indicator is a measure of transit availability that incorporates service coverage, frequency, and duration; the availability and quality of pedestrian routes to transit stops; and population and job density. The TLOS indicator’s basic concept is that at any given minute, a transit vehicle serves a small group of people; that is, those people who could board a vehicle when leaving their job site or residence that minute, walk no more than a specified distance to a transit stop, and wait no more than a specified time for a vehicle to arrive. Geographical information system–based software developed for the TLOS project can be applied to every transit vehicle for each minute in a day. The data can be compiled for time frames ranging from 15 minutes to 1 week to assess the amount of service for each part of a transit system’s service area. The TLOS indicator was tested in Tallahassee, Florida, and produced results compatible with, but more detailed than, the availability measures contained in the Transit Cooperative Research Program’s Transit Capacity and Quality of Service Manual. Potential applications include service evaluation, transportation modeling, and improvement of modal-split calculations.
Transit Passenger Perceptions of Transit-Related Crime Reduction Measures
Authors: Reed Thomas B. , Wallace Richard R. , Rodriguez Daniel A.
Published: April 2007

Violent crimes against public transit bus operators and passengers in Michigan were studied. The study was funded by the Michigan Department of Transportation and conducted by the University of Michigan in early 1999. A survey approach examined transit passenger perceptions of numerous transit-related crime reduction measures, primarily patrol and security, design actions, and technological innovation. The respondents ranked emergency telephones for passengers and increased lighting as the best crime prevention measures. The survey was part of a wider study that also surveyed transit agencies and transit vehicle operators.
Cost of Pavement Damage Due to Heavier Loads on Louisiana Highways: Preliminary Assessment
Authors: Roberts Freddy L. , Djakfar Ludfi
Published: April 2007

A preliminary assessment is made of the impact of increasing the gross vehicle weight (GVW) from current legal limits to 100,000 lb (45 400 kg) on vehicles hauling sugarcane, rice, timber, and cotton. Sections of road were chosen in each area of Louisiana where commodities are produced, the amount of each commodity hauled was estimated, and the effects of increasing the GVW were evaluated for each section using pavement design models. Design data were secured from the Louisiana Department of Transportation and Development computer database and project files to determine the pavement design parameters and traffic estimates for each road. The number of vehicles hauling the 1998 harvest payload was estimated, a projected increase in the production of each commodity was estimated on the basis of government statistics, and rehabilitations were designed with the use of the 1986 AASHTO Design Guide for a 20-year analysis period. Present worth (PW) was calculated for each GVW scenario for each roadway. Comparisons of PW between the weight scenarios showed that increases in GVW have more effect on state and U.S. highways than they do on Interstate highways. Any increase in GVW over current limits increases the cost of overlays and decreases the length of time before an overlay is required. The cost increase due to increasing the GVW is substantial. Fee structures should be modified by the legislature so that these costs are paid for either through the current registration and overweight permit fee structure or through some new tax, such as a ton-mile tax.
Effect of Oregon’s Axle-Weight-Distance Tax Incentive
Authors: Rufolo Anthony M. , Bronfman Lois , Kuhner Eric
Published: April 2007

Oregon’s weight-mile tax was amended in 1990 to provide for a lower tax rate for trucks weighing more than 36 320 kg (80,000 lb) to which axles were added. The additional axles within a weight class reduce the amount of road damage. The tax break was largely based on equity considerations, since trucks within a weight class tend to do less road damage if they have more axles. However, the tax reductions also created an economic incentive to add axles and thus reduce road damage. Whether the tax break actually led to an increase in the number of axles within weight classes and a reduction in the amount of road damage is investigated. Statistical data indicate that a small increase occurred in the number of axles in most weight classes and a large increase occurred in mileage by the heaviest trucks with the most axles. These increases reduced the damage per ton shipped on trucks subject to the axle incentive, but to determine if this was due to the weight-mile tax is not possible. A series of structured interviews supplemented the statistical analysis and indicates that the tax incentive is not a major determinant of truck configuration. One reason for this is that regulatory constraints, particularly weight limits, limit the effectiveness of the tax incentives.
Economic Evaluation of Bridge Seismic Retrofit Improvements
Authors: Baker Brent , Miller Richard
Published: April 2007

Travel-related and damage-avoidance benefits and costs of conducting seismic retrofit improvements to arterial bridges are examined, with consideration of the risk posed by a relatively low probability but high damage earthquake (a design level event). The city of Seattle’s arterial bridges and viaduct structures serve as vital components of the urban road network, providing for the ongoing transportation needs of citizens and commerce. Failure of these bridges in the event of an earthquake would have significant negative impacts for the movement of people and goods, and thus on the local economy. Shoring up the city’s bridges to resist earthquake damage would clearly bring benefits, thereby preventing the impassable arterial bottlenecks that would otherwise occur. The question is whether or not the potential benefits of seismic retrofit improvements warrant their investment costs, thereby providing an economically efficient use of public dollars. For the purpose of addressing this question, a methodology for evaluating the potential benefits and costs associated with bridge seismic retrofit improvements is presented, quantifying these impacts for a two-phase retrofit program and considering the results in light of risk and uncertainty. The evaluation procedures developed consider a major earthquake with defined probability and compare the travel-related and damage-avoidance benefits that would be generated by retrofit improvements with their associated implementation costs. Emphasis is placed on travel impacts because researchers would find nontransportation economic impacts extremely difficult to quantify without knowing all of the other physical, built environment impacts that would occur with a major seismic event. Standard measures of economic feasibility are reported, and in the case of Seattle, seismic retrofit improvements demonstrate moderate positive economic rates of return. The implications posed by expected utility theory for risk-averse decision makers in such cases involving earthquake uncertainty are also discussed.
Pavement and Bridge Cost Allocation Analysis of the Ontario, Canada, Intercity Highway Network
Authors: Ghaeli Reza , Hutchinson Bruce G. , Haas Ralph , Gillen David
Published: April 2007

Continuous growth of road transportation demand has resulted in soaring rates of road deterioration and maintenance costs. Full road cost recovery by direct charging of road users is gaining more popularity as governments face pressure to reduce general taxes, and full road cost recovery can promote more efficient use of the road system. A sound charging system requires reliable models for infrastructure deterioration and sound methodologies for cost allocation. In Ontario, new pavement performance models have been recently developed with more emphasis on separating the effects of traffic from the effects of environmental forces on flexible pavements in different geographic locations. The recent models and data have been used to investigate the cost implications of different vehicle configurations and road characteristics for the Ontario pavements and bridges. The results are used for the allocation of costs to various users of the road system. The results generally have implied that initial road design specifications, vehicle configurations, and the types and locations of roads could significantly affect user cost responsibilities. The analyses determined that proper selection of vehicles and payload amounts could result in up to 6 percent savings in pavement costs. The analyses showed that a fair and efficient cost allocation can be achieved by consideration of various vehicle and road characteristics and their interrelated cost implications, rather than solely on the basis of damage implications of each vehicle.
Optimization Model for Large-Scale Bus Transit Scheduling Problems
Authors: Banihashemi Mohamadreza , Haghani Ali
Published: April 2007

A procedure is presented for solving real-world large-scale multiple depot vehicle scheduling (MDVS) problems considering the route time constraints (RTCs). The procedure is applied to some test problems and then to a real-world problem. The real-world problem is the transit bus scheduling problem of the mass transit administration (MTA) in Baltimore, Maryland. The RTCs are added to the MDVS problem to account for real-world operational restrictions such as fuel consumption. Formulation of the MDVS problem, the set of constraints for considering the time restriction, and a heuristic procedure for solving the MDVS problems with RTCs are discussed. Application of the proposed procedures in solving bus scheduling problems in large cities requires a reduction in size of those problems in terms of number of variables and constraints. Two techniques are proposed to decrease the size of the real-world problems. Combining these techniques results in a strategy to reduce the MTA problem size into a manageable and solvable size. The solutions to the reduced size problems are further improved by solving a series of single depot vehicle scheduling problems for each of the MTA depots. The final results from the proposed model are compared with the MTA’s January 1998 schedule. The comparison indicates that the proposed model improves on the MTA schedules in all aspects. The improvements are 7.90 percent in the number of vehicles, 4.66 percent in the operational time, and 5.77 percent in the total cost.
Mixed Global and Local Assignment Algorithms for Quasi-Dynamic Local Truckload Trucking Operations with Strict Time Windows
Authors: Regan Amelia C. , Jagannathan Sreeram , Wang Xiubin
Published: April 2007

Examined are the trade-offs associated with local and global, but myopic, assignment heuristics for local truckload trucking operations such as those associated with drayage operations near intermodal facilities. These operations involve a combination of loads that are known at the beginning of the day and those that arrive dynamically throughout the day. Some of the dynamically arriving loads are revenue-generating moves, and others are trailer, chassis, or container repositioning moves. Because a significant fraction of the day’s loads are known a priori, dispatchers would like to be able to construct schedules for the day and then to make minor changes to these schedules as the day progresses. The efficiency of an operation in which new loads are added to or appended to schedules constructed at the start of the day versus one in which the whole system is reoptimized several times during the day is examined. The reoptimization method does not seek to preserve current schedules, but the local optimization techniques do. Solutions were examined with a geographic information system-based simulation model developed for this purpose.
Local Optimization Approaches to Solve Dynamic Commercial Fleet Management Problems
Authors: Mahmassani Hani S. , Kim Yongjin , Jaillet Patrick
Published: April 2007

Strategies are presented that a dispatcher may use to take advantage of real-time information to manage a fleet of trucks to provide truckload pickup-and-delivery service under time windows for service and computing time constraints. These strategies are hybrid in that they combine very efficient dynamic local heuristic rules for quick initial assignment, with formal optimization-based procedures for subsequent load reassignment decisions within the time requirements of the dynamic problem. Simulation experiments were performed to test these strategies under alternative specifications and parameter values. In the first stage, the acceptance decision and initial schedule of trucks were determined so as to respond rapidly to incoming customer requests for service. Then, some time is allowed to improve the schedule of trucks by swapping the assigned loads using local optimization at the reassignment stage. Two strategies are described to control the computation time of the reassignment optimization problem by controlling the problem size. The simulation results confirm the significant potential for reassignment strategies under real-time information to improve system performance and suggest that considerable improvement is attainable even under restricted problem formulations.
Introducing Platoon Dispersion into an Analytical Dynamic Assignment Process
Authors: Shin Michael S. , Ran Bin , He Rachel R. , Choi Keechoo
Published: April 2007

The platoon dispersion factor is integrated into an analytical dynamic traffic assignment (DTA) model. The objective of integrating platoon dispersion with DTA is to improve the representation of flow propagation in the DTA model and enforce the first in, first out constraints. A set of new linear formulations for flow propagation that include explicit constraints on the movement of traffic in a transportation network is presented. Based on the numerical examples, it can be demonstrated that platoon dispersion is realized in an analytical DTA model by using the existing solution algorithm.
Effective Safety Improvements Through Low-Cost Treatments
Authors: Datta Tapan K. , Feber David , Schattler Kerrie , Datta Sue
Published: April 2007

A vast majority of traffic crashes in urban areas occur at signalized intersections. Roadway geometry, traffic control, adjacent land uses, and environmental factors at intersections often contribute to the high incidence of traffic crashes and injuries. A public-private partnership project to identify high-crash and high-risk locations in the city of Detroit was initiated in 1996. Eighteen candidate sites were selected, and an extensive engineering study was conducted to develop countermeasures to help alleviate the traffic crash problem at the selected sites. The Automobile Association of America, Michigan, was the private partner in this joint venture and, in partnership with the city of Detroit, was a major contributor to covering the cost of improvements. The selection of countermeasures was based on state-of-the-art methodology and analysis, and implementation of the selected countermeasures at some of the sites was undertaken as the initial phase of the project. A comprehensive before-and-after evaluation study was performed at three of the improved sites. The study revealed that the safety improvements that were implemented lowered both crash and severity experience. The differences between the before and after crash frequencies proved to be statistically significant. Additionally, a benefit-cost analysis at the study locations indicated extraordinary results. This research presents the evaluation study results and discusses the countermeasures and improvements that were the most successful in mitigating traffic crash problems at the selected study locations.
Geographic Information Systems: Unique Analytic Capabilities for the Traffic Safety Community
Authors: Miller John S.
Published: April 2007

Geographic information systems (GIS) have been used for more than a decade to display crash sites. Now that their novelty has worn off, the traffic records community should ask what additional analytical benefits GIS can uniquely provide. A literature review illustrates that safety-related GIS analytical capabilities surpass the common practice of producing crash location pin maps. Additional useful GIS techniques include using grid-based modeling; producing increasingly accurate collision diagrams; verifying disparate sources of crash data; applying spatially based statistical applications; examining crash location patterns for causal factors; aligning public opinion with real data; and improving routing capabilities for pedestrians, bicyclists, and hazardous material carriers. This research explores GIS analytic capabilities that can be practically applied to crash data evaluation. A case study demonstrates that despite limited budgets and imperfect data, GIS can still help to identify potential crash countermeasures. Using a typical non-GIS source of crash data (a software package that records crashes at either an intersection or a midblock location), it was possible to place approximately 82 percent of crash locations within a GIS. When private property crashes were excluded from this process, the placement rate climbed to an estimated 94 percent for intersections and 87 percent for midblock locations. By focusing the case study on understanding the practical spatial analytical capabilities rather than merely the mechanics of specific GIS software, one can eventually take advantage of the more extensive crash and roadway data sets that will become available. Despite its many capabilities, however, GIS has not eliminated the need for a comprehensive safety analysis framework integrating the spatial and statistical queries necessary for engineering, enforcement, or educational improvements.
Automated Enforcement of Red Light Running Technology and Programs: A Review
Authors: Smith David M. , McFadden John , Passetti Karl A.
Published: April 2007

Automated enforcement involves the use of image capture technology to monitor and enforce traffic control laws, regulations, or restrictions. The increase in aggressive driving and the high percentage of crashes that occur at intersections led to the development and implementation of automated enforcement technology to detect and cite motorists who enter a signalized intersection in violation of the red phase. The primary focus of this research was to establish how well the automated enforcement system achieves its principal objective: reducing crashes and red light running (RLR) violations at signalized intersections. Evaluations of automated enforcement programs at three locations in the United States were performed as part of this research. The automated enforcement programs in New York City; Polk County, Florida; and Howard County, Maryland, were reviewed as a part of this research. Some of the major findings from this research are as follows: ( a) In 1997 there were over 789,000 crashes at signalized intersections, of which 97,000 were attributed to RLR; ( b) In 1997, 961 deaths were attributed to RLR; ( c) Electronic enforcement is a proven technique used globally to curb RLR violations and crashes; ( d) A synthesis of automated RLR enforcement programs in the United States showed promising results; ( e) New York City has the oldest automated RLR enforcement program in the United States and has yielded a 20 percent reduction in violations since 1993; ( f) Although additional data quantifying the effect of automated RLR enforcement campaigns are needed for Polk and Howard counties, preliminary findings are promising; ( g) A 10-step process for successful implementation of an automated RLR enforcement program was illustrated.
Novelty Helmet Use by Motorcycle Riders in Florida
Authors: Turner Patricia A. , Hagelin Christopher A.
Published: April 2007

Although Florida law requires all motorcyclists to wear helmets, 16 percent of all motorcycle drivers and 30 percent of all their passengers killed in motorcycle crashes in 1996 were not wearing protective helmets. In addition, the use of novelty helmets may be on the rise in states with universal helmet laws. The objectives of this research were to determine motorcycle helmet use rates on Florida roadways and to estimate the level of novelty helmet use by motorcycle occupants. A total of 2,498 motorcyclists in 13 Florida counties were observed over a 2-month period. Data were collected on helmet use and type, motorcycle type, gender, and use of other safety equipment. Almost all motorcycle occupants wore some type of helmet; the observed state-level usage rate was 99.5 percent. However, a significant number of these helmets were novelty helmets. The type of helmet motorcyclists choose to wear may be related to the type of motorcycle driven and the gender of the driver and passenger. Overall, novelty helmet use was higher for passengers than for drivers, and the majority of observed novelty helmets were on motorcycle occupants riding cruiser-type motorcycles. Moreover, females exhibited lower rates of compliance than males, especially when associated with cruiser-type motorcycles. Although the survey did not collect information about the reasons for the increase in novelty helmet use, possible explanations may be that novelty helmets are more readily available at lower cost, and that there is an overall perceived lack of enforcement of the motorcycle helmet use law.
Alcohol-Impaired Motorcycle Crashes in Hawaii, 1986 to 1995: An Analysis
Authors: Kim Karl , Kim Sungyop , Yamashita Eric
Published: April 2007

The purpose of this research is to review and describe data on the nature and extent of alcohol-impaired motorcycle-riding crashes in Hawaii. Using comprehensive police crash data, the differences between impaired and nonimpaired riders involved in crashes, in terms of various demographic characteristics, helmet use, license status, roadway environments, and injury outcomes, are described. In addition to various demographic and behavioral factors associated with impaired rider crashes, clear temporal patterns also have been detected. After summarizing these effects, a logistic regression model is built to explain the likelihood of an impaired motorcycle crash as a function of rider characteristics as well as environmental and temporal factors. In addition to age-specific determinants of impaired crash involvement, time factors such as weekends and nighttime, and licensing (out-of-state or no licenses) are strongly associated with impaired rider crashes. These findings could be used to enhance enforcement efforts as well as public information and safety education programs.
Field Evaluation of a Leading Pedestrian Interval Signal Phase at Three Urban Intersections
Authors: Van Houten Ron , Retting Richard A. , Farmer Charles M. , Van Houten Joy
Published: April 2007

About 37 percent of pedestrian injury crashes and 20 percent of fatal pedestrian crashes occur at intersections. Many conventional countermeasures include traffic control devices that either increase pedestrian attention to potential vehicle-pedestrian conflicts or encourage drivers to yield to pedestrians. A noteworthy limitation of these warning and prompting messages is their reliance on a voluntary behavioral response. Public education and enforcement campaigns have also generally not produced tangible and long-lasting safety benefits. This research, conducted at three urban intersections, examined the influence of a 3-s leading pedestrian interval (LPI)—a brief and exclusive signal phase dedicated to pedestrian traffic—on pedestrian behavior and conflicts with turning vehicles. The introduction of a 3-s LPI reduced conflicts between pedestrians and turning vehicles and reduced the incidence of pedestrians yielding the right-of-way to turning vehicles.
Keeping Passenger Surveys Up to Date: A Fuzzy Approach
Authors: Friedrich Markus , Mott Peter , Noekel Klaus
Published: April 2007

The knowledge of travel demand is an essential prerequisite for analyzing and planning transport supply. Obtaining travel-demand data for a transit system requires passenger surveys that combine counts and interviews. Passenger surveys have two unpleasant characteristics: they are expensive, and the results of such studies tend to lose their validity fairly rapidly. For these reasons, the development of techniques that reduce survey costs and keep demand matrices up to date is gaining increasing interest. Details of a technique for computer-aided processing of passenger surveys are given, and a method for continuous updating of demand matrices is presented. Because traffic surveys represent only a snapshot situation, the proposed updating method employs a fuzzy approach to consider that traffic volumes vary within a certain bandwidth.
Moving Crowds in Chicago: Baseball and the Fourth of July
Authors: Abrams Steven H.
Published: April 2007

The Chicago Transit Authority (CTA) is often called on to transport large numbers of spectators attending popular special events. Although these situations bear similarities to normal peak-hour traffic, they are characterized by longer-lasting streams of intense traffic volume. Facilities and operating practices designed for peak-hour traffic are usually unable to handle these extraordinary inflows. Therefore, facilities and operations must be adapted to deal with these extreme conditions. Today, CTA experiences two major types of special-events situations. The first type of situation is sporting events, such as professional baseball, football, and basketball games, which originate predictable traffic from a specific site at predetermined times. Therefore, a nearby transit facility such as a rapid-transit station can be designed to service expected traffic volumes. Second, Chicago hosts a growing list of special events that are located in less-well-defined areas, which may change over time. Attendance at this second type of event is often difficult to predict and measure. Therefore, permanent facilities must be adapted to serve such infrequent demand. Also, special-events operations planning must be coordinated carefully with outside agencies. The discussion focuses on how CTA has designed both facilities and operations to deal with the crowds generated by both scenarios. CTA serves many sporting events, including Cubs baseball games at Wrigley Field. Also, every year Chicago hosts a fireworks display held on the night of July 3. A description is included of the design of facilities and operations that facilitate these special events.
Transit Services in a Competitive Market
Authors: Lo Hong K. , Yip C.W. , Lee K.H.
Published: April 2007

Since the new Hong Kong International Airport debuted on July 6, 1998, ground trips to the airport have undergone drastic changes. A number of transit modes are provided to connect the new airport with the territory, including three major ones—Airport Express Line (AEL), Air Bus (A-bus), and External Bus (E-bus). All of these transit services are operated by profit-driven businesses, dividing the 167,000 daily trips. Currently, the Hong Kong government imposes fare control on the bus services, whereas the rail service (e.g., AEL) is exempt from such control. The fare changes resulting from this competition were examined to assess their impacts on the traveling public as well as on each operator. In addition, an evaluation was made of the impact of deregulating this policy of fare control and allowing the operators to compete freely in a noncooperative manner. Transit services in a competitive market could lead to very different outcomes. For some districts, a transit operator could increase revenue by fare increases, whereas for other districts, revenue increase could be achieved only with fare reduction. Where and why competition falls into these different operating paradigms is an interesting topic for investigation. The methodology for this analysis, as well as the results based on actual data, is discussed.
Customer Satisfaction Among Transit Riders: How Customers Rank the Relative Importance of Various Service Attributes
Authors: Weinstein Aaron
Published: April 2007

One of the reasons transit organizations collect customer-satisfaction information is to help set priorities for service improvements. Customer-satisfaction survey results can help managers choose from among a long list of service attributes (e.g., vehicle cleanliness or on-time performance) to more optimally focus their organization’s attention and resources. To make these choices, managers need to know how important each service characteristic is to their customers. Common techniques for gauging the relative importance of various service characteristics to transit customers are examined. Empirical data from the Bay Area Rapid Transit District are used to compare and contrast several of these techniques. The analysis suggests that a relatively simple approach using a ranking of bivariate correlation coefficients from high to low may be the most advantageous technique for ranking the relative importance of transit attributes from a customer perspective.
Effects of Fare Incentives on New York City Transit Ridership
Authors: Hirsch Lawrence R. , David Jordan J. , Hickey Robert L. , Cravo Valdemar
Published: April 2007

Over a period of 3 years starting in 1994, Metropolitan Transportation Authority (MTA) New York City Transit (NYCT) installed automated fare-collection technology systemwide and introduced MetroCard, an electronic fare card capable of storing value and time. Over a single year starting in July 1997, NYCT introduced the following fare incentives: ( a) free intermodal transfers, ( b) a discount on bulk purchase of value on MetroCard, ( c) a reduction in the express bus fare, and ( d) 7- and 30-day unlimited-ride MetroCards. (A 1-day unlimited-ride MetroCard was added in January 1999.) The effect of these fare incentives on subway and bus ridership is examined, and the changes due to the fare incentives are presented in the context of historical trends.
Impacts of an Advanced Public Transportation System Demonstration Project
Authors: Levine Jonathan , Hong Qiang , Edward Hug George , Rodriguez Daniel
Published: April 2007

In 1997 the Ann Arbor (Michigan) Transportation Authority began deploying a set of integrated, advanced public transportation system technologies in its vehicles, stations, and control center. Selected findings are summarized of a multidimensional evaluation of the effects of the system on schedule adherence and transfer time, passenger perception, and drivers. Some improvement in on-time performance was observed in vehicle departures from major transfer points, though not in arrivals. Modest improvements were observed in transfer coordination for routes planned for timed transfers. Deployment of the system did not raise passengers’ rating of relevant aspects of their transit experience, but impacts of individual system elements were rated favorably. Focus groups and a driver survey revealed a fundamentally favorable attitude toward the deployment of technology coupled with some concern about limitations that it might impose on driver communications and on-the-job creativity. Benefits of the system that were not apparent during the period of the evaluation but may materialize over the longer term include prevention of and response to safety- and security-related incidents and enhanced information for transit planning.
Experimental and Numerical Study of Laterally Loaded Pile Groups with Pile Caps at Variable Elevations
Authors: McVay Michael C. , Zhang Limin , Han Sangjoon , Lai Peter
Published: April 2007

A series of lateral load tests were performed on 3×3 and 4×4 pile groups in loose and medium-dense sands in the centrifuge with their caps located at variable heights to the ground surface. Four cases were considered: Case 1, pile caps located above the ground surface; Case 2, bottom of pile cap in contact with the ground surface; Case 3, top of pile cap at the ground surface elevation; and Case 4, top of pile cap buried one cap thickness below ground surface. All tests with the exception of Case 1 of the 4×4 group had their pile tips located at the same elevation. A special device, which was capable of both driving the piles and raining sand on the group in flight, had to be constructed to perform the tests without stopping the centrifuge (spinning at 45 g). The tests revealed that lowering the pile cap elevation increased the lateral resistance of the pile group anywhere from 50 to 250 percent. The experimental results were subsequently modeled with the bridge foundation-superstructure finite element program FLPIER, which did a good job of predicting all the cases for different load levels without the need for soil–pile cap interaction springs (i.e., p-y springs attached to the cap). The analyses suggest that the increase in lateral resistance with lower cap elevations may be due to the lower center of rotation of the pile group. However, it should be noted that this study was for pile caps embedded in loose sand and not dense sands or at significant depths. The experiments also revealed a slight effect for the case of the pile cap embedded in sand with a footprint wider than the pile row. In that case the size of the passive soil wedge in front of the pile group, and consequently the group’s lateral resistance, increased.
Use of Dynamic Cone Penetrometer to Control Compaction of Granular Fill
Authors: Jayawickrama Priyantha W. , Amarasiri Aruna L. , Regino Pedro E.
Published: April 2007

Granular material is commonly used as backfill and embedment material for buried structures, including thermoplastic pipe. Proper compaction of this material is crucial to the successful performance of the pipe. However, the commonly used Proctor density approach cannot be used for the field compaction control of these materials because it does not provide a well-defined moisture-density relationship. An alternative method used by the authors for compaction control of such materials is described. This method involves a device known as the dynamic cone penetrometer (DCP). Findings are presented from a series of DCP tests conducted on a range of granular backfill materials that belong to ASTM D 2321 Classes I and II. These materials were compacted using ( a) an impact rammer and ( b) a vibratory plate compactor. The level of compaction energy was varied by changing the number of passes. The data obtained from these tests are presented in the form of DCP blow count profiles, which are then used as the basis for comparison between different materials, compaction equipment, and levels of compaction energy. A series of full-scale load tests conducted on high-density polyethylene (HDPE) pipe installations is also described. An overview is provided of how the DCP data may be combined with load-deflection data from full-scale load tests to establish guidelines for compaction control of pipe backfill.
Stabilization of Embankment Slope with Geofoam
Authors: Jutkofsky Walter S. , Teh Sung J. , Negussey Dawit
Published: April 2007

A case history is presented describing the use of expanded polystyrene (EPS) geofoam blocks to treat an unstable roadway embankment slope involving clayey soils. The selection of the geofoam treatment was based upon its ability to be constructed and have the least impact on both the environment and adjacent homeowners. The site subsurface conditions, engineering properties of EPS, design analysis, and construction phases are reviewed. Potential traffic safety problems associated with differential icing of roadways caused by the presence of geofoam blocks beneath the pavements were minimized by using a thicker subbase layer in the geofoam-treated area. Data from an instrumentation program consisting of an inclinometer, extensometers, and thermistors are presented. Pavement temperature readings collected from areas with and without geofoam treatment are compared to investigate potential differential icing on the roadway.
Dutch Design Manual for Lightweight Pavements with Expanded Polystyrene Geofoam
Authors: Duškov M.
Published: April 2007

The use of expanded polystyrene (EPS) geofoam instead of traditional “heavy” sand for pavement subbases can reduce or even eliminate the additional load on the subsoil, thus decreasing or eliminating the settlement of pavement structures on a compressible subsoil. Experience with EPS geofoam is very positive, but a uniform design procedure does not yet exist for this type of structure. Optimization of the existing EPS pavement design guidelines and their improvement has demanded materials research on EPS, the use of three-dimensional finite-element pavement models, and in situ full-scale measurement. Extensive materials research provided data for the stress-strain response of EPS under representative loading and environmental conditions. Three-dimensional modeling enabled critical evaluation of existing design methodologies by analyzing pavements with different road bases, different EPS types, and different asphalt thicknesses. In situ measurements by means of built-in strain transducers in asphalt provided data for verification of the three-dimensional modeling. Furthermore, evaluation and monitoring of Dutch projects with EPS geofoam were carried out to define problematic aspects from the practical point of view. On the basis of the research findings, the current Dutch design guidelines have been revised and optimized. In order to make this knowledge easily accessible, an official Dutch design manual for lightweight pavements with EPS geofoam was published under the auspices of the Center for Research and Contract Standardization in Civil and Traffic Engineering. An outline of the manual is presented.
Liquefaction Mitigation Using Stone Columns Around Deep Foundations: Full-Scale Test Results
Authors: Ashford Scott A. , Rollins Kyle M. , Case Bradford V S. , Weaver Thomas J. , Baez Juan I.
Published: April 2007

The results presented were developed as part of a larger project analyzing the behavior of full-scale laterally loaded piles in liquefied soil, the first full-scale testing of its kind. Presented here are the results of a series of full-scale tests performed on deep foundations in liquefiable sand, both before and after ground improvement, in which controlled blasting was used to liquefy the soil surrounding the foundations. Data were collected showing the behavior of laterally loaded piles before and after liquefaction. After the installation of stone columns, the tests were repeated. From the results of these tests, it can be concluded that the installation of stone columns can significantly increase the density of the improved ground as indicated by the cone penetration test. Furthermore, it was found that the stone column installation limited the excess pore pressure increase from the controlled blasting and substantially increased the rate of excess pore pressure dissipation. Finally, the stone columns were found to significantly increase the stiffness of the foundation system by more than 2.5 to 3.5 times that in the liquefied soil. This study provides some of the first full-scale quantitative results on the improvement of foundation performance due to stone columns in a liquefiable deposit.