bluuebunny/crossref_metadata_2025 huggingface dataset:
Fractional Split-Distribution Model for Statewide Commodity-Flow Analysis
Authors: Sivakumar Aruna , Bhat Chandra
Published: April 2007

A relatively simple, but comprehensive, approach to modeling interregional commodity-flow volumes is proposed and applied. The approach estimates the fraction of commodity consumed at each destination zone that originates from alternate production zones. The resulting fractional split model for commodity-flow distribution is more general in structure than the typical gravity model used today for statewide freight planning. The empirical analysis applies the fractional split model to analyze interregional commodity flows in Texas.
New Intelligent Transport Systems Applications in Europe to Improve Bus Services
Authors: Hounsell Nick , Wall Graham
Published: April 2007

Applications of information technology are expanding rapidly across all modes of transport, under the general heading of intelligent transport systems (ITS). For bus-based public transport, a cluster of applications has been developed that can help improve the efficiency and performance of buses on the street, thus helping to provide a real transport alternative to the private car. An initial summary of a range of such ITS examples in Europe is provided, including automatic vehicle location (AVL), bus priority in traffic control systems, automatic ticketing systems, automatic camera enforcement systems, and variable message signs. Then the focus shifts to one area where activity is most pronounced—the implementation of AVL systems and their integration with urban traffic control (UTC) systems. A review of typical AVL/UTC systems operational in Europe is then presented through the identification of some eight alternative architectures and associated system characteristics, such as the technologies used and the location of bus priority “intelligence.” This is followed by a summary of examples from cities in Europe that have implemented these architectures, together with typical results illustrating the effectiveness of these systems. The diversity of architectures, technologies, and systems is recognized as beneficial in providing customer choice, but can generate a significant difficulty for decision makers in local authorities wishing to invest in public transport ITS technologies. A concluding discussion lists some of the key issues involved in this investment process.
Wireless Internet Access to Real-Time Transit Information
Authors: Maclean S. D. , Dailey D. J.
Published: April 2007

A transit vehicle information system that delivers estimated departure times for buses at user-selectable geographic locations to Internet-enabled mobile devices is reported. The system is not merely schedule based; it makes use of real-time vehicle position reports to predict travel times to future locations. How the physical restrictions of mobile devices (e.g., screen size and input options) affect user interaction and data presentation is discussed. The system is hosted on the World Wide Web and is freely available. An overview of the system architecture is provided and some preliminary usage results are presented.
California’s Zero-Emission Vehicle Mandate: Linking Clean-Fuel Cars, Carsharing, and Station Car Strategies
Authors: Shaheen Susan A. , Wright John , Sperling Daniel
Published: April 2007

To reduce transportation emissions and energy consumption, policy makers typically employ one of two approaches—changing technology or changing behavior. These strategies include demand management tools, such as ridesharing and vehicle control technologies that involve cleaner fuels and fuel economy. Despite the benefits of a combined policy approach, these strategies are normally employed separately. Nevertheless, they have been linked occasionally, for instance in the electric station car programs of the 1990s. Station cars are vehicles used by transit riders at the start or end of a trip. In 1990, the California Air Resources Board (CARB) focused on reducing mobile air pollution by mandating that automakers introduce clean vehicles through its Zero-Emission Vehicle (ZEV) Mandate. In 1998, significant flexibility was introduced through partial ZEV credits for very-low-emission vehicles. In 2000, CARB left the ZEV mandate intact, but began considering new approaches, including station cars and carsharing. Carsharing is the short-term use of a shared-use vehicle fleet. In January 2001, recognizing the potential for station cars and carsharing to further improve air quality by reducing vehicle miles traveled—particularly with transit linkages—CARB proposed additional ZEV credits for vehicles in such programs. Thus, the mandate would formally link demand management and clean vehicles. Explored are carsharing and station car developments, lessons learned, the ZEV mandate, and the proposed credit structure. Finally, policy and research recommendations are discussed for enhancing the success and effect of this combined approach.
Environmental Justice in the Transportation Planning Process: Southern California Perspective
Authors: Pfeffer Nancy , Wen Frank H. , Ikhrata Hasan M. , Gosnell James R.
Published: April 2007

Title VI of the 1964 Civil Rights Act prohibits recipients of federal funds from discriminating on the basis of race, color, or national origin. This law underpins federal regulations and policies collectively referred to under the label “environmental justice.” Metropolitan planning organizations (MPOs), which receive federal funds for transportation planning, must demonstrate that their plans and programs comply with environmental justice expectations. The Southern California Association of Governments, an MPO in Los Angeles and the largest MPO in the United States, employed a number of new analytical techniques to assess the distribution of benefits and burdens of its 2001 Regional Transportation Plan, a 25-year blueprint for regional transportation investments. In general, the analysis showed that the plan would not cause inequitable distributions of benefits or burdens for minority or low-income residents of the region. A disproportionate aviation noise burden was identified in the analysis and influenced regional policy makers to pursue a distributed regional aviation policy to minimize this and related aviation impacts.
Use of Accelerated Aging to Predict Behavior of Recycled Materials in Concrete Pavements: Physical and Environmental Comparison of Laboratory-Aged Samples with Field Pavements
Authors: Taylor Eighmy T. , Cook Raymond A. , Gress David L. , Coviello Anthony , Spear Jean C. M. , Hover Kenneth , Pinto Roberto , Hobbs Susannah , Kosson David S. , Sanchez Florence , van der Sloot Hans , Korhonen Charles , Simon Marcia
Published: April 2007

Future behavior of recycled materials in highway applications is often difficult to predict. Accelerated aging is one means of exploring the long-term physical and environmental performance. Coal fly ash (CFA), routinely used as a cementitious replacement in portland cement concrete pavement, was selected as a model system in an accelerated aging approach. US-20 near Fort Dodge, Iowa, was used as a source of field-aged pavement slab material and concrete mixture proportions. This pavement, constructed in 1987, experienced early failure and distress. The role of CFA, if any, in the failure is not known. Three types of accelerated aging treatments were chosen and applied on laboratory prisms made with the US-20 mixture proportions: arrhenius aging (AA), cyclic loading, and freeze-thaw exposure. Physical and environmental response variables were used to examine the pavement slab and the aged laboratory prisms. The aging protocol affected both physical and chemical properties of the monoliths. It took about 9 months of elapsed time to age specimens to an equivalent age of about 4 years. The equivalent ages matched well with the time frame seen in the field for the onset of early distress. Most response variables for the aged laboratory prisms and the field samples were similar, suggesting that the aging method reasonably produced a pavement of similar age and distress. The AA treatment produced an unexpected loss of strength, suggesting that the accelerated aging promoted the onset of a deleterious reaction. Distinguishing the source of trace metals in leachates was difficult, for all components (CFA, aggregates, cement) had similar elemental compositions and leachability. The use of both physical and environmental response variables showed linkages between compressive strength, microcracking, fine pore structure, Cl diffusive leaching (efflux related to road salting that increases the concentration of Cl in the monolith), and Ca diffusive leaching (related to change in matrix structure and loss of Ca).
Effects of Pedestrian Treatments on Risky Pedestrian Behavior
Authors: Siques Joaquin T.
Published: April 2007

The effects of pedestrian treatments on risky pedestrian behavior at light rail transit grade crossings were examined. Five pedestrian treatments were evaluated—( a) pedestrian automatic gates, ( b) a prototype active pedestrian warning device, ( c) a prototype active “Look Both Ways” sign, ( d) barrier channelization at a skewed crossing, and ( e) a “Stop Here” pavement marking. Pedestrian grade-crossing treatments were installed at three grade crossings along the Tri-County Metropolitan Transportation District of Oregon MAX light rail system in Portland, Oregon. The pedestrian treatments and the crossing geometry varied at the three locations, providing for three unique evaluations on the effectiveness of different pedestrian treatments at grade crossings. The grade crossings were videotaped for at least 1 week both before and after the installation of the pedestrian treatments. The data were evaluated using a before-and-after statistical approach to determine the effects of the treatments on risky pedestrian behavior. The statistical evaluation of the data shows that pedestrian treatments result in a statistically significant reduction in risky pedestrian behavior. The greatest reductions were found with pedestrian automatic gates. The results, however, also demonstrate that various pedestrian treatments can sometimes increase risky pedestrian behavior.
What Is an Appropriate Sheeting Specification for Prismatic Construction and Maintenance Signs?
Authors: Brich Stephen C.
Published: April 2007

The Virginia Department of Transportation’s (VDOT) Road and Bridge Specifications require that retroreflective sheeting used on construction and maintenance activity signs be a fluorescent prismatic lens type that is retroreflective at entrance angles as great as 50° with observation angles of 0.2° and 0.5°. Because the validity of this requirement was recently questioned, this study was conducted to determine if the specification were appropriate or not. The study results indicate that VDOT’s wide entrance angle requirement is not appropriate for construction and maintenance signs and that observation angles should receive more attention than entrance angles.
Comparison of Observed Retroreflectivity Values with Proposed FHWA Minimums
Authors: Nuber Luke , Bullock Darcy
Published: April 2007

Until recently, no federal guidance existed on the retroreflectivity of highway signs, and the replacement policy has been left to the discretion of local officials. FHWA has now published a proposed set of minimum retroreflectivity requirements for traffic signs. The proposed minimum retroreflectivity values published by FHWA were compared with retroreflectivity values observed from signs with ASTM Type III sheeting in the state of Indiana. Research found that approximately 4% of signs scheduled for removal in 2000 or 2001 were below the proposed FHWA minimums. Having different retroreflectivity minimums for different speeds and sign sizes unnecessarily complicates the proposed minimums. Using the single most conservative retroreflectivity value for each color would be sufficient.
Cost- and Longevity-Based Scheduling of Paint and Thermoplastic Striping
Authors: Abboud Nasser , Bowman Brian L.
Published: April 2007

Because no national guidelines exist on establishing pavement marking service life, the scheduling of road striping has been inconsistent among maintenance agencies. This study establishes a way to set striping schedules that accounts for factors affecting scheduling, mainly application cost, service lifetime, and user cost relative to crashes during the striping lifetime. Striping useful lifetime is defined as the striping age beyond which pavement markings become ineffective in relaying necessary vehicle positioning information, when deteriorated pavement marking retroreflectivity reaches a minimum acceptable value. An exponential regression model was used to depict the relationship between striping age and average daily traffic (ADT), using a retroreflectivity threshold of 150 mcd/m2/1x. Striping useful lifetime was established for ADT levels using exponential regression analysis. Application costs were based on the latest available unit costs from the Alabama Department of Transportation for white and yellow longitudinal stripes of paint and thermoplastic markings. Using the National Safety Council estimates of crash severities, user costs were based on the dollar equivalency of the damage to vehicles and occupants in retroreflectivity-related crashes. The data were extracted from the crash experience of approximately 1,300 mi (2100 km) of state highways in 32 Alabama counties. For use in scheduling striping, paint and thermoplastic striping costs were compared on an equivalent annual basis, accounting for application and user costs. Although the crash data and retroreflectivity data were collected on Alabama roads, the findings and conclusions are applicable to areas of warmer climate where snowfall is uncommon.
Soil Bioengineering as an Alternative for Roadside Management: Benefit-Cost Analysis Case Study
Authors: Hagen Shannon , Salisbury Sandra , Wierenga Marlies , Xu George , Lewis Lisa
Published: April 2007

As an environmentally compatible and cost-efficient alternative for roadside management, soil bioengineering has become increasingly important and attractive. Soil bioengineering uses live plants and plant parts as building materials for engineering and ecologically sound solutions to erosion control, slope and stream bank stabilization, landscape restoration, and wildlife habitats. However, not all decision makers are aware of the specific benefits of this approach. This case study applied a benefit-cost analysis to an experimental soil bioengineering demonstration project to evaluate the cost-effectiveness of soil bioengineering as an alternative to traditional roadside management. Traditional roadside management methods (geotechnical solutions) were used as the baseline, and soil bioengineering treatments were treated as an investment alternative. Cost savings, along with other environmental benefits, were assessed and compared with construction costs. The effects of life cycle, effectiveness, and discounting were included in the analysis to ensure comparability between both treatments. The analytical results demonstrate that soil bioengineering methods, if technically feasible, could be adopted to produce equal or better economic and environmental results. The findings of the research project and the economic analysis indicate that soil bioengineering is an efficient and environmentally beneficial tool for roadside management.
Performance of Louisiana’s Chip Seal and Microsurfacing Program, 2002
Authors: Temple William , Shah Shashikant , Paul Harold , Abadie Christopher
Published: April 2007

A 5-year field performance study was conducted of the 1995–1996 Chip Seal and Microsurfacing projects with a summary of data generated by the Louisiana Department of Transportation and Development’s pavement management group. The pavement management data set includes performance indicators such as the international roughness index, crack analysis, rut depth, and ground-penetrating radar thickness. A subjective survey designed for maintenance surfacing was developed and used on this same set of projects. The pavement condition rating was examined from the point of pretreatment and annually until spring of 2001. The survey suggests that treatments will improve a pavement’s initial condition, but no conclusion can be drawn on the effect on pavement condition index (PCI) over time compared with untreated pavements, as all pavements’ PCI curves are similar and are independent of PCI before treatment. General observations for chip seal projects are as follows: the median PCI was 75 after 52 months with a significant reduction in cracking; 20% of the projects showed moderate to heavy bleeding; rutting was not evident; and measurement for skid resistance was very good. For a life expectancy of 5 years, the equivalent annual cost (EAC) of a chip seal is approximately 27 cents a year. For micro-surfacing projects, the median PCI of microsurface sections is approximately 85 after 60 months of service with significantly fewer cracks detected after treatment. Projects with 0.5-in. initial rut showed substantial reduction after treatment. The friction numbers (FN) for smooth tire are in the low teens to low thirties on 50% of the projects. The lower numbers are attributed to a combination of the use of limestone and high asphalt content. Sandstone sections exhibited FNs in the 50s. For a life expectancy of 6 years, the EAC is about 49 cents a year.
Ten-Year Field Performance Evaluation of Joint Reseating Project
Authors: Lynch Larry N. , Chehovits Jim G. , Luders David G.
Published: April 2007

In 1989, the U.S. Army Engineer Research and Development Center and Crafco, Inc., initiated a research effort to develop improved materials and processes for sealing and resealing joints in portland cement concrete pavements. The objectives of the research were to develop specification limits for improved field performance of hot-applied, jet-fuel-resistant (JFR) and non-jet-fuel-resistant (non-JFR) sealants and obtain field data to determine the field performance of different sealants and installation configurations. The research effort was divided into a laboratory phase and a field phase. The laboratory phase focused on identifying ideal properties that a hot-applied non-JFR and hot-applied JFR sealant should possess, evaluating commercially available sealants to determine if they exhibited those properties, and developing improved hot-applied materials that would exhibit as many of those properties as feasible. The field phase was initiated in June 1991 at Fairchild Air Force Base near Spokane, Washington. The focus of this effort was to determine the field performance of field-molded sealants (including improved materials versus commercially available sealants) and possible improvements in field performance by changing the sealant installation geometry. Thirteen different field-molded sealants were installed, and their field performance was monitored at different times over 10 years. The evaluations indicated that two of the hot-applied, asphalt-based sealants, four of the silicone-based sealants, and one of the coal tar–based sealants had life expectancies of greater than 10 years. The improved JFR and non-JFR sealants exhibited better field performance than the standard hot-applied sealants included in the evaluation.
Testing Calcium Nitrite Corrosion Inhibitor in Concrete
Authors: Medford William M.
Published: April 2007

Over the last 14 years, the North Carolina Department of Transportation (NCDOT) has been specifying the addition of calcium nitrite corrosion inhibitor to concrete in chloride-corrosive environments. To ensure that nitrite inhibitor has been added at the specified dose, NCDOT has been testing both hardened and plastic concrete. Several instances have been observed in which the nitrite level did not meet the specified minimum. Data relative to sampling techniques, chemical testing, and the variability of hardened concrete are summarized. Data are also presented about the ability of nitrite to leach from a concrete pile in immersion service in a marine location. The results of a new method for testing plastic concrete are compared to the old method for hardened specimens.
Estimating Agency Cost of Maintenance, Repair, and Rehabilitation for Florida Bridges
Authors: Sobanjo J. O. , Thompson Paul D. , Lewis Mathew , Kerr Richard
Published: April 2007

The Florida Department of Transportation (FDOT) recently conducted a study to develop agency cost factors for maintenance, rehabilitation, and repair (MR&R) of bridges, for the state’s implementation of the AASHTOWare Pontis® Bridge Management System. The study analyzed three information systems on maintenance and construction history available at the FDOT. Pontis defines many combinations of bridge element, environment, condition, and feasible action, resulting in more unit cost values than can be estimated from the available data. To simplify cost determination, a classification scheme (MR&R Action Sub-category) was devised to group the Pontis combinations. Statistical analysis was performed on the raw cost data to extract useful numbers from the available data sources. The results were supplemented with the judgment of an FDOT panel of experts. Although the panel found the analysis of historical data to be useful for 70% of the actions considered, only 50% of the actions had a statistically significant sample, and only 15% were usable directly from a statistical analysis. The main issues were differences in data collection units and differences or uncertainties in the scope of recorded actions. The study recommended improvements in the automated systems to enhance the ability to use the data in future updates of the agency cost model.
Influence of Vertical Alignment on Horizontal Curve Perception: Phase II: Modeling Perceived Radius
Authors: Hassan Yasser , Sayed Tarek , Bidulka Shaun
Published: April 2007

Phase I of a study established that perception of horizontal curvature depends on the overlapping vertical alignment. A horizontal curve radius will be perceived incorrectly if the curve overlaps with a crest or sag vertical curve. Phase II quantified the extent of such erroneous perception. An experiment involving a three-dimensional static presentation was carried out to determine the mean value of perceived horizontal curve radius for different sets of alignment parameters. The results of the experiment were analyzed statistically to examine the effects of the alignment parameters on the perceived radius. The parameters that were found to significantly affect the perceived radius were the type of overlapping vertical curve, actual radius, and turning direction (on crest and sag curves) and sight distance (on sag curves). In addition, simple statistical models were developed using regression analysis to estimate the perceived radius of any horizontal curve in a combined alignment.
Three-Dimensional Visualization Approach to Illustrating Esthetic Concepts for Highway Design
Authors: Janikula Thomas , Garrick Norman W.
Published: April 2007

Realistic and dynamic visual models were developed that can be used in a teaching context for illustrating concepts that affect the appearance and fit of a highway alignment. The models consist of short video clips of the highway taken from the perspective of a vehicle’s windscreen. These video images of the roadway are coupled with graphs showing the corresponding vertical and horizontal alignment of the roadway. The users of these models can simulate a drive over the selected highway segment and visually assess the appearance and continuity of the alignment. They can then study the accompanying alignment graphs to evaluate how different combinations of vertical and horizontal elements affect the appearance and continuity of the alignment. Each of the video clips was selected to illustrate either a good or bad example of a specific concept affecting alignment design. Some of the concepts illustrated include the coordination of vertical and horizontal alignment and consistency in alignment development. The video clips were developed using images and data from the Connecticut Department of Transportation’s photologging system.
Methodology to Calculate Sight Distance Available to Drivers at Skewed Intersections
Authors: Son Young-Tae , Kim Sang-Gu , Lee Jin-Kak
Published: April 2007

A methodology was developed to calculate sight distance available to drivers at skewed intersections of minor roads that are controlled by stop signs. The methodology considers the fact that the sight distance may vary depending on the position of the driver and the different lines of sight given to the driver by different types of vehicles. Through field observations, factors are found that affect the sight distance available to drivers. The factors include intersection geometry, the vehicle’s dimension, and the driver’s field of view. With the sight triangle properly drawn, equations were developed for calculating the available sight distance considering these factors. Values of sight distance were compared with stopping-sight distance of vehicles on the crossroads by varying design speeds and intersection angles. Nomographs were developed that can be used by road designers or operators to check if a skewed intersection satisfies the sight-distance requirement.
Clear-Water Abutment Scour Prediction for Simple and Complex Channels
Authors: Richardson J.R. , Trivino Robert
Published: April 2007

One hundred and sixty-one laboratory and one field clear-water abutment scour data sets were regressed using a Box-Tidwell power transformation procedure. The predictive equation was verified using additional laboratory data for compound channels. A momentum ratio term was used to account for flow redistribution, differences in overbank geometries, and scale sizes. The regression identified the most applicable and dominant independent variables that affect the magnitude of clear-water abutment scour. The resulting equation has a significantly lower standard error of estimate than previously published equations. This formulation is more robust and accurately predicted abutment scour depth at both laboratory and prototype scale. With additional refinement, improved abutment scour predictive equations can be realized by using alternative regression procedures and including the momentum ratio to buffer the effect of abutment length at large prototype scales.
Assessment of NCHRP Report 350 Test Conditions
Authors: Mak King K. , Bligh Roger P.
Published: April 2007

The appropriateness of test conditions specified in NCHRP Report 350 was assessed. The assessment focused on the basic Test Level 3 and addressed two areas of interest: the effects of higher speed limit on impact speed and the appropriateness of 25° for the impact angle. The following conclusions and recommendations were drawn on the basis of the results of the analysis: ( a) the current test impact speed of 100 km/h (62.2 mph) should be maintained, ( b) the current impact angle of 25° for Test 11 of length-of-need sections of permanent longitudinal barriers should be maintained, ( c) the test impact angle should be reduced from 25° to 20° for Test 11 of length-of-need sections of temporary longitudinal barriers, and ( d) the test impact angle should be reduced from 25° to 20° for Test 21 of barrier transition sections. However, the selection of impact conditions is more a policy decision than a technical issue to be resolved in the update of NCHRP Report 350 guidelines.
Investigating Premature Deterioration of a Concrete Highway
Authors: Rangaraju Prasada Rao
Published: April 2007

Premature deterioration of concrete on Trunk Highway 169 near Hibbing, Minnesota, triggered an investigation to determine the potential cause of the distress. The deterioration manifested in the form of severe cracking and spalling in the top 75 mm (3 in.) of the pavement near the transverse joints. Investigation of cores obtained from locations near joints and midpanel indicated that the air void system in the top portion of the pavement was compromised initially (during construction) by nonuniform vibration across the depth of the concrete pavement and later by in-filling of the marginal air void system with secondary products. Absence of any evidence indicating the structural failure of the pavement or of the loadtransfer devices suggested that inferior concrete and poor construction practices were primarily responsible for the pavement failure.
Heat Removal from Mass Concrete Footing
Authors: Liu Chiu , Meline Robert , Lee James N.
Published: April 2007

Removing heat from mass cement concrete footings during initial construction is vital to ensure the quality of the footings after curing. When the temperature of concrete exceeds 70°C, heat released from the hydration of cement can initiate microscopic cracks that may grow larger during or after curing. The temperature of a mass concrete structure can be controlled by various means, depending on the situation. With temperature data collected from a large footing for a bridge column of the ongoing I-580/I-680 Interchange Project, temperature variations were modeled with time and location in a large concrete footing by means of the Fourie–Biot heat conduction equation. Agreement between analytic predictions and field data was found for the physical parameters characterizing the reactions and material properties of the concrete. Possible ways of lowering the concrete temperature are suggested for the future San Francisco–Oakland Bay Bridge East Spans Project.
Voting Outcomes of Local Tax Ballot Measures with a Substantial Rail Transit Component: Case Study of Effects of Transportation Packages
Authors: Werbel Richard A. , Haas Peter J.
Published: April 2007

This research explores the effect of transportation package characteristics, both qualitative and quantitative, on the outcome of tax ballot measures with a substantial rail transit component. Seventeen recent ballot measures, each occurring in 1995 or later, in 12 communities are examined with information generated through on-site and telephone interviews and written documentation. Key findings suggest that ( a) failed campaigns may successfully be repeated with appropriate adjustments; ( b) multimodal packages tend to be more readily approved by voters; ( c) providing perceived geographic equity is both important and challenging, with one feasible approach involving decentralized planning; ( d) involving influential representatives from the business community, environmental groups, and the political community in the planning process is important in building an effective supporting coalition, although developing a package acceptable to all these groups can be difficult, and ( e) voters appear to be more sensitive to the tax expiration date than to the sales tax rate.
Urban Transport Strategy for Colombo, Sri Lanka
Authors: Mitric Slobodan
Published: April 2007

International sharing of urban transport experiences may be beneficial for practice and help give form to a concept of strategy. Main problems and issues of urban transport in Colombo, Sri Lanka, were identified, and a strategy was proposed for improving the performance of the transport system for travelers and its impacts on urban development. On the streets of Colombo, buses compete for scarce space with passenger vehicles, motorcycles, and vans. Crossing bicycle riders and pedestrians have an even more difficult time. Privately operated buses dominate the passenger market, complemented by three public-sector operators, the survivors of several waves of reorganizations and reforms. Both groups of operators suffer from having to charge low fares and from increasing street congestion, but private operators freely manage their staff and vehicles and do not follow prescribed routes, stops, and frequencies. Strategic issues involve the pricing of services in the presence of two distinct markets (low-income travelers and those who own or aspire to own a vehicle) and two inconsistent regulatory regimes, the absence of reserved street space for public transport vehicles, and intergovernmental relations concerning jurisdiction and funding for urban transport modes. Pivotal propositions involve redefining the government role as regulator of public transport services; using the social assistance system to help low-income travelers (thus liberating fare making); upgrading the suburban lines of Sri Lanka Railways into a separate, high-quality, regional rapid transit network; and adopting a regionally oriented road pricing and financing system.
Simulating No-Passing Zone Violations on a Vertical Curve of a Two-Lane Rural Road
Authors: El-Zarif Jamal , Hobeika Antoine , Rakha Hesham
Published: April 2007

A unique simulation was developed to evaluate the performance of a system designed to detect and warn of no-passing zone violations on vertical curves of two-lane rural roads. After the system architecture and the system design were developed, a special software program was written to test the system functions and assess the system performance. Many roadway-, vehicle-, and driver-related parameters were introduced in this simulation to reflect real-world situations as closely as possible. More than 19,500 violation runs were made for the basic scenario to reflect and calibrate the actual conditions of the parameters involved. The simulation was used as a tool to conduct a system evaluation by applying it for cases both with and without the warning system. The simulation outcome for the case without the warning system was very close to the actual real-world condition (1.41 versus 0.71 crashes per year). The simulation runs of the case with the warning system showed that the system could virtually eliminate all head-on collisions, should the violators obey the early warning messages displayed.
Benefit–Cost Analysis of the Commercial Vehicle Information Systems and Networks Program
Authors: Brand Daniel , Parody Thomas E. , Orban John E. , Brown Vincent J.
Published: April 2007

A comprehensive benefit–cost analysis was performed using the results of model deployments of the Commercial Vehicle Information Systems and Networks (CVISN) program, which provides electronic credentialing and electronic screening of heavy trucks to improve their safe and efficient to operation. CVISN is intended to enable a regulatory system to operate at reduced cost and increased effectiveness for both its users and society. Benefit–cost analysis is a public-sector evaluation tool that compares all of a project’s benefits to society with all of the project’s costs to society. The question to be answered in undertaking such an analysis is: do these benefits exceed the costs? In the case of the CVISN programs evaluated, considerable public benefits can be expected, and the benefits greatly exceed the costs. From the results of several representative CVISN deployment scenarios examined, it appears prudent to proceed with full deployment of such systems.
Retroreflective Material Specifications and On-Road Sign Performance
Authors: Bible Rollin C. , Johnson Norbert
Published: April 2007

Retroreflective materials for traffic control devices are designed to return light from a vehicle’s headlamps back to the driver. Recent advances in material technology have created prismatic retroreflective sheeting. This type of material does not have the predictability in its retroreflective performance of the older, glass-bead material. The ASTM recently recognized three new types of prismatic material for traffic control devices. The on-road performance of these new material types was examined through the use of computer simulation of sign luminance. Inputs to the computer model included vehicle dimensions, headlamp illumination data, material retroreflectivity data, sign placement, and roadway geometry. A variety of sign positions and roadway types was included to illustrate the similarities and differences among the three new types of material. The ranking of the three materials in terms of sign-luminance performance depends on the roadway configuration and the viewing distance. ASTM Type VII is shown to be comparable to Type VIII at long distances with small entrance angles but superior to Type VIII and IX in large entrance-angle situations. ASTM Type IX is shown to have higher luminance at shorter distances associated with sign-legibility distance ranges. Engineers and specifiers are encouraged to evaluate on-road sign performance at night before making material choices.
Model of Overhead-Sign Luminance Needed for Legibility
Authors: Holick Andrew J. , Carlson Paul J.
Published: April 2007

Photometric models can be used to estimate the sign luminance provided for different roadway scenarios. While photometric models provide specific luminance curves, no standards or design criteria exist that can be used to define how much luminance is needed by a driver. For instance, if one desired to design a sign based on an assumed design driver and other pertinent criteria, no guidelines or models are available. An analysis has been designed to develop a model for determining the minimum luminance needed to read overhead guide signs. The model was developed based on legibility data collected for defining the minimum luminance needed to read everyday words on overhead guide signs.
Technique for Comparing Operation of Alternative Interchange Types
Authors: Bonneson James A. , Lee Sangsoo
Published: April 2007

Interchanges have been the focus of several recent studies that attempted to identify the conditions in which one interchange type is more efficient than another. However, the guidance offered is of such a general nature that it is difficult to apply with confidence in a specific situation. The objective of this study was to describe an interchange evaluation technique that is of sufficient precision to facilitate interchange-type selection or planning-level evaluations of interchange performance. This technique was based on the use of characteristic curves that define the relationship between interchange delay and the sum-of-critical-flow-ratios. This sum represents a unique parameter that combines the effect of signal phase sequence, traffic volume, number of lanes, and saturation flow rate. A family of characteristic curves was developed and used to illustrate the interchange evaluation technique. The curves describe the relationship between delay and the sum-of-critical-flow-ratios for the single-point urban interchange (SPUI) and the tight urban diamond interchange (TUDI), both serving frontage-road systems. For the range of conditions considered, it was concluded that the TUDI will generally operate with less delay than the SPUI.
Adaptation of Highway Capacity Manual 2000 for Planning-Level Analysis of Two-Lane and Multilane Highways in Florida
Authors: Washburn Scott S. , McLeod Douglas S. , Courage Kenneth G.
Published: April 2007

A planning-level adaptation was developed of the Highway Capacity Manual (HCM) 2000 procedure for estimating the level of service (LOS) on two-lane and multilane highways in Florida. The problems associated with planning-level adaptations in general and with uninterruptedflow highways in particular were identified. Although much of the adaptation was achieved though the use of default values for data items, some departures from the HCM procedures were required. The most significant deviation was the creation of a third class of two-lane highway to supplement the two classes currently defined in the HCM. A case was made for the existence of this class and its inclusion in a future edition of the HCM. The Florida Department of Transportation’s planning-level methodology, termed HIGHPLAN, is well suited to its intended application, which is planning-level analysis of two-lane and multilane highways in Florida. It maintains fidelity to the HCM procedures to the extent that Florida conditions will allow and Florida users will accept. As long as they are understood, the departures from the HCM should not pose significant problems for users outside of Florida. The planning-level methodology has also been implemented in a software program that produces LOS estimates and service volume tables covering sitespecific conditions.
Uncertainty in Operational Analysis of Two-Lane Highways
Authors: Luttinen R. Tapio
Published: April 2007

The Highway Capacity Manual (HCM) 2000 provides methods to estimate performance measures and the level of service for different types of traffic facilities. Because neither the input data nor the model parameters are totally accurate, there is an element of uncertainty in the results. An analytical method was used to estimate the uncertainty in the service measures of two-lane highways. The input data and the model parameters were considered as random variables. The propagation of error through the arithmetic operations in the HCM 2000 methodology was estimated. Finally, the uncertainty in the average travel speed and percent time spent following was analyzed, and four approaches were considered to deal with uncertainty in the level of service.
Comparison of Greenshields, Pipes, and Van Aerde Car-Following and Traffic Stream Models
Authors: Rakha Hesham , Crowther Brent
Published: April 2007

Three car-following models were compared: the Greenshields single-regime model, the Pipes two-regime model, and a four-parameter single-regime model that amalgamates both the Greenshields and Pipes models. The four-parameter model proposed by Van Aerde and Rakha is less known but is currently implemented in the INTEGRATION 2.30 software. The Greenshields and Pipes models were considered because they represent state-of-the-practice models for several types of microscopic and macroscopic software. The Greenshields model is widely used in macroscopic transportation planning models. In addition, the Pipes model is implemented in a number of microscopic traffic simulation models including CORSIM and VISSIM. Steady-state car-following behavior is also related to macroscopic traffic stream models to develop calibration procedures that can be achieved using macroscopic loop detector data. The study concluded that the additional degree of freedom that results from including a fourth parameter (Van Aerde model) overcomes the shortcomings of the current state-of-the-practice traffic stream models by capturing both macroscopic and microscopic steady-state traffic behavior for a wide range of roadway facilities and traffic conditions. Also developed was a procedure for calibrating the Pipes car-following model using macroscopic field measurements that can be obtained from loop detectors. Although this calibration procedure does not overcome the inherent shortcomings of the Pipes model, it does provide an opportunity to calibrate the CORSIM and VISSIM car-following behavior to existing roadway conditions more efficiently and without the need to collect microscopic traffic data.
Reconsideration of Sample Size Requirements for Field Traffic Data Collection with Global Positioning System Devices
Authors: Li Shuo , Zhu Karen , van Gelder B. H. W. , Nagle John , Tuttle Carl
Published: April 2007

The use of Global Positioning System (GPS) technologies has expanded to perform traffic data collection for transportation studies such as work zone studies. To generate reliable results from the data acquired by using GPS devices, it is necessary to investigate such factors as sample size requirements that may affect a specific study and to establish a consistent method for data collection. It has been confirmed that the Institute of Transportation Engineers’ Manual of Transportation Engineering Studies usually underestimates the sample sizes for travel time and delay studies. However, the hybrid method developed by Quiroga and Darcy overestimates the sample sizes. A modified equation is presented to estimate the minimum sample sizes for collecting field data with GPS devices. Travel speed may be more stable and can be easily measured for travel time and delay studies. Stopped delay varies considerably at intersections, and the sample sizes depend to a large extent on the permitted errors. Work zone layout and construction activities will create variations in vehicle flow within the work zone. To estimate the sample size requirements, it is advisable to use the standard deviation to measure the data dispersion, and a minimum of three initial test runs is required. GPS devices with sufficient accuracy usually require 5 to 10 samples for travel time and delay studies and work zone studies. Stopped delay studies may require a large sample of up to 30 test runs.
Effects of Ambient Light, Camcorder Settings, and Automated License Plate Reader Settings on Plate Transcription Rates
Authors: Plotnikov Michael , Shuldiner Paul W.
Published: April 2007

The ability of an automated license plate reading (ALPR) system to convert video images of license plates into computer records depends on many factors. Of these, two are readily controlled by the operator: the quality of the video images captured in the field and the internal settings of the ALPR used to transcribe these images. A third factor, the light conditions under which the license plate images are acquired, is less easily managed, especially when camcorders are used in the field under ambient light conditions. A set of experiments was conducted to test the effects of ambient light conditions, video camcorder adjustments, and internal ALPR settings on the percent of correct reads attained by a specific type of ALPR, one whose optical character recognition process is based on template matching. Images of rear license plates were collected under four ambient light conditions: overcast with no shadows, and full sunlight with the sun in front of the camcorder, behind the camcorder, and orthogonal to the line of sight. Three camcorder exposure settings were tested. Two of the settings made use of the camcorder’s internal light meter, and the third relied solely on operator judgment. The license plates read ranged from 41% to 72%, depending most strongly on ambient light conditions. In all cases, careful adjustment of the ALPR led to significantly improved read rates over those obtained by using the manufacturer’s recommended default settings. Exposure settings based on the operator’s judgment worked best in all instances.
Dynamic Camera Calibration in Support of Intelligent Transportation Systems
Authors: Pumrin Suree , Dailey Daniel J.
Published: April 2007

An algorithm with which to estimate mean vehicle speed from roadside cameras owned by a traffic management agency is presented. These roadside cameras are not calibrated nor are calibration marks available in the scene. However, estimating camera calibration coefficients is the most important step in extracting quantitative information about the three-dimensional world from the two-dimensional image. Within this frame-work an algorithm is presented that performs a simplified dynamic calibration and estimates mean vehicle speed. Many algorithms depend on point correspondences between the earth coordinates and the image coordinates as well as targets of known shape to obtain accurate results. However, in the work presented, the goal is to estimate the mean of a distribution of vehicle speeds, and it is demonstrated that a simplified form of calibration is adequate for making an accurate mean speed estimate. Dynamic camera calibration is performed with training sets of 10-s video sequences. The proposed method detects moving vehicles in a set of consecutive frames. This information, together with mean vehicle dimension estimates, is used to create scaling factors that are used to infer a relationship between motion in the image and motion in the earth coordinate system. The proposed algorithm has a camera model with a reduced number of camera calibration parameters. The algorithm is validated with simulated data and actual traffic scenes.