bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender Differences in Activities and Mobility in the Netherlands, 1975 to 1990
Authors: van Beek Paul , Kalfs Nelly , Blom Ursula
Published: April 2007

As in many other countries, a growing number of women in the Netherlands are entering the labor market. The difference between male and female participation in paid work is decreasing, and more men are taking care of domestic duties. It is expected that these changes will lead to growing numbers of task combiners and to more similar patterns of travel behavior for men and women. The intention of the present research is to investigate these expectations for the situation in the Netherlands. For this goal two groups of time budget data for the period from 1975 to 1990 were analyzed. The focus was on gender differences in trends in time use and mobility. The results indicate that between 1975 and 1990, the distribution of paid work and domestic work by men and women changed, more men and women were performing combinations of obligatory tasks, gender differences in mobility became smaller, and car use, both for men and for women, depended heavily on the workload of an out-of-home paid job.
Generation of Synthetic Daily Activity-Travel Patterns
Authors: Kitamura Ryuichi , Chen Cynthia , Pendyala Ram M.
Published: April 2007

Microsimulation approaches to travel demand forecasting are gaining increased attention because of their ability to replicate the multitude of factors underlying individual travel behavior. The implementation of microsimulation approaches usually entails the generation of synthetic households and their associated activity-travel patterns to achieve forecasts with desired levels of accuracy. A sequential approach to generating synthetic daily individual activity-travel patterns was developed. The sequential approach decomposes the entire daily activity-travel pattern into various components, namely, activity type, activity duration, activity location, work location, and mode choice and transition. The sequential modeling approach offers practicality, provides a sound behavioral basis, and accurately represents an individual’s activity-travel patterns. In the proposed system each component may be estimated as a multinomial logit model. Models are specified to reflect potential associations between individual activity-travel choices and such factors as time of day, socioeconomic characteristics, and history dependence. As an example results for activity type choice models estimated and validated with the 1990 Southern California Association of Governments travel diary data set are provided. The validation results indicate that the predicted pattern of activity choices conforms with observed choices by time of day. Thus, realistic daily activity-travel patterns, which are requisites for microsimulation approaches, can be generated for synthetic households in a practical manner.
Comparative Analysis of Day-to-Day Trip-Chaining Behavior of Urban Commuters in Two Cities
Authors: Jou Rong-Chang , Mahmassani Hani S.
Published: April 2007

The day-to-day variation in automobile commuter trip-chaining behavior is investigated. Models are developed to relate trip-chaining patterns to three types of factors: ( a) socioeconomic characteristics, ( b) workplace conditions, and ( c) traffic system characteristics. The analysis is based on a diary survey of commuters in Dallas, Texas. The transferability of commuter trip-chaining behavior is also examined through comparison with results of a previous study conducted in Austin, Texas. Commuters engaged in many nonwork stops during commuting trips, indicating that trip chaining is an essential characteristic of commuting behavior. The analysis reveals that socioeconomic attributes, workplace conditions, and commuter preference exert similar influences in the two cities, whereas traffic system characteristics (namely, no-stop travel time) have different influences on morning stop frequency behavior in the two cities. For the evening, no attributes were found to have significantly different effects between Austin and Dallas.
Value of Traffic Assignment and Flow Prediction in Multiattribute Network Design: Framework, Issues, and Preliminary Results
Authors: McCord Mark R. , Hidalgo Dario , Goel Prem , O’Kelly Morton E.
Published: April 2007

The well-defined concept of value of perfect information (VOPI) was used to assess the value of improving flow prediction and the relative value of improving components of the prediction system. The concept is introduced with a simplified example of choosing whether to build a highway segment in a corridor, and then the example is extended to a network and more realistic components are incorporated. The examples are worked through to illustrate the general approach, the types of results that could be obtained, and the issues that arise. The probability distributions of the attributes—cost, time, fuel consumption, and vehicle emissions—used to summarize uncertainty in prediction are important components when calculating VOPI. An approach to modeling these distributions and the flow distributions on which they are conditioned is presented. Unlike traditional approaches, the present one recognizes uncertainty in the model itself and not only in the inputs and parameters of the model. The VOPI of arc flows is calculated for the network example and is compared with the project costs. VOPI is used to indicate that the marginal value of developing an error-free traffic assignment model would be much greater than that of developing an error-free trip distribution model in the example. The research and implementation issues raised by the example are discussed.
Incorporating Feedback in Travel Forecasting
Authors: Loudon William R. , Parameswaran Janaki , Gardner Brian
Published: April 2007

The Clean Air Act Amendments of 1990 (CAAA) introduced new requirements for how transportation modeling for air quality analysis must be performed in nonattainment areas. Because of the degree to which vehicle emission rates (on a grams-per-mile basis) are affected by speed, specific attention has been given to how speeds are estimated and subsequently used in the travel forecasting and emissions estimation process. CAAA and guidelines issued in the years following introduction of the act require that speeds used in the process be realistic in comparison to what might be observed on the road and be reasonably consistent throughout the modeling process. In most traditional modeling processes that model trip generation, trip distribution, mode choice, route assignment, and emissions separately and sequentially, it has not been unusual to find different speeds (and travel times) used in different parts of the process. A description of two different research and development efforts that have produced new methods and guidelines for introducing feedback into the travel and emissions forecasting process to ensure consistent use of speeds is provided. COMSIS Corporation developed for FHWA a method for introducing feedback into the traditional four-step process by using an iterative process through all of the steps until the process converged to a stable set of link speeds. The methodology was used to test the effects of introducing feedback on model results under different levels of network congestion (feedback affects the results only when there is congestion in the network). The project resulted in a report documenting the methods, pitfalls, and common concerns for introducing feedback. A summary of the research conclusions from the project is provided.
Ferry Route Level of Service
Authors: Savage Joseph P.
Published: April 2007

Transportation service level measurements have been commonly used and accepted for highway systems, but similar service measures for ferry systems are less common, especially from the users’ point of view. An approach to measuring ferry route level of service is described that allows comparisons among ferry routes and between ferries and alternate modes such as highways (i.e., drive-around choices) and transit. The recommended approach focuses on excess user waiting times (excess delay) by mode (automobile, registered carpool or vanpool, bus, truck, and walk-on passenger), combined with calibrated relationships between volume-to-capacity (V/C) ratio and user delays for forecasting purposes. Data on waiting times for vehicles in the queues were collected on all ferry routes serviced by Washington State Ferries, and an extensive statistical analysis was performed to compute the relationships between V/C ratios and excess waiting times. Excess delay was defined as the waiting time for missed vessel sailings due to overloads, if any, after a ferry patron has arrived at the dock. User delays were expressed in two forms: absolute number of minutes of waiting time, and the number of boat sailings missed before boarding a ferry. The “boat wait” concept was introduced to differentiate between excess delays caused by congestion that prevents a driver from boarding the next ferry, and delays related to the amount of service provided on a route as reflected in the headways between vessels.
Simplified Approaches to Ferry Travel Demand Forecasting
Authors: Savage Joseph P.
Published: April 2007

Large ferry systems and ferry systems operating in major urban areas can often rely on regional travel models using the traditional four-step travel demand forecasting process to predict ridership levels for their routes. However, smaller agencies and agencies in rural areas often do not have either the data or the resources to develop and implement complex forecasting models for their systems. A variety of simplified forecasting methods are reviewed that can be implemented with inexpensive, commercially available software using ferry traffic counts and readily available socioeconomic data from published sources. Data from the Woods Hole, Martha’s Vineyard and Nantucket Steamship Authority are used to illustrate and compare the applications of the following methods: simple annual compound growth rate (5- or 10-year historical trend, 12-month moving totals, weighted trends), simple linear trend extrapolation of time series data, and simple and multiple linear regression models using population, employment, and other independent variables for available outside sources.
Development and Application of a Revenue and Ridership Forecasting Model for Ferry Service
Authors: Baker T. Brent , Deardorf Raymond G.
Published: April 2007

A combination of statistical approaches is used to develop near-to mid-range ridership and revenue forecasting models for Washington State Ferries for use in quarterly budget updates. Econometric regression models use historical and forecast trends in state economic and demographic variables to project systemwide ridership by six fare categories for different fare scenarios. Time series analysis models are used to project ferry ridership at the individual route level by six fare categories. The sum of the time series route forecasts is then calibrated to the econometric systemwide totals to yield unconstrained ridership forecasts by route and fare category. A capacity constraint model handles cases where the demand for vehicle travel exceeds vessel capacity by generating ridership ceilings for different service scenarios. Finally, the appropriate fares are applied to the ridership projections to arrive at revenue forecasts over a 10-year horizon.
Boston Harbor Project: Water Transportation Systems Support a Major Urban Construction Project
Authors: Corbett Stephen
Published: April 2007

The Massachusetts Water Resources Authority (MWRA) is an independent authority. MWRA is constructing new primary and secondary wastewater treatment facilities on Deer Island in Boston Harbor. The new facilities will replace two antiquated primary treatment plants located on Deer Island and Nut Island, which is in Quincy Bay. Information on project management, project mitigation, and the facility siting process is provided, and the marine facilities and transportation services and the Boston Harbor Project labor agreement are described.
Relationship Between Pavement Temperature and Weather Data: Wisconsin Field Study to Verify Superpave Algorithm
Authors: Bosscher Peter J. , Bahia Hussain U. , Thomas Suwitho , Russell Jeffrey S.
Published: April 2007

Six test sections were constructed on US-53 in Trempealeau County by using different performance-graded asphalt binders to validate the Superpave pavement temperature algorithm and the binder specification limits. Field instrumentation was installed in two of the test sections to monitor the thermal behavior of the pavement as affected by weather. The instrumentation was used specifically to monitor the temperature of the test sections as a function of time and depth from the pavement surface. A meteorological station was assembled at the test site to monitor weather conditions, including air temperature. Details of the instrumentation systems used and analysis of the data collected during the first 22 months of the project are presented. The analysis was focused on development of a statistical model for estimation of low and high pavement temperatures from meteorological data. The model was compared to the Superpave recommended model and to the more recent model recommended by the Long-Term Pavement Performance (LTPP) program. The temperature data analysis indicates a strong agreement between the new model and the LTPP model for the estimation of low pavement design temperature. However, the analysis indicates that the LTPP and Superpave models underestimate the high pavement design temperature at air temperatures higher than 30°C. The temperature data analyses also indicate that there are significant differences between the standard deviation of air temperatures and the standard deviation of the pavement temperatures. These differences raise some questions about the accuracy of the reliability estimates used in the current Superpave recommendations.
Critical Review of Voids in Mineral Aggregate Requirements in Superpave
Authors: Kandhal Prithvi S. , Foo Kee Y. , Mallick Rajib B.
Published: April 2007

Reports of increased difficulties in meeting the minimum voids in mineral aggregate (VMA) requirements have surfaced with the recent use of Superpave volumetric mix design. The low VMA of Superpave mixes generally can be contributed to the increased compactive effort by the Superpave gyratory compactor. This has led to the increased use of coarser asphalt mixes (gradations near the lower control points). However, the minimum VMA requirements in Superpave volumetric mix design for these coarse mixes are the same as those developed for the dense mixes designed by the Marshall method. Literature review has indicated that the rationale behind the minimum VMA requirement was to incorporate at least a minimum permissible asphalt content into the mix to ensure its durability. Studies have shown that asphalt mix durability is directly related to asphalt film thickness. Therefore, the minimum VMA should be based on the minimum desirable asphalt film thickness instead of on a minimum asphalt content because the latter will be different for mixes with different gradations. Mixes with coarse gradation (and, therefore, a low surface area) have difficulty meeting the minimum VMA requirement based on minimum asphalt content despite thick asphalt films. A rational approach based on a minimum asphalt film thickness has been proposed and validated. The film thickness approach represents a more direct, equitable, and appropriate method of ensuring asphalt mix durability, and it encompasses various mix gradations.
Effect of Mineral Filler Type and Amount on Design and Performance of Asphalt Concrete Mixtures
Authors: Tayebali Akhtarhusein A. , Malpass Glen A. , Paul Khosla N.
Published: April 2007

Three methods for classifying aggregate particle shape and texture—AASHTO TP33, ASTM D3389, and the flow rate method—were evaluated. These methods were used to rank four natural river sands and a crushed granite from good to poor performance based on the criteria established by each method. Test results indicate that all methods easily distinguished the crushed aggregate from the natural river sands. The AASHTO TP33 and the flow rate method were found to be somewhat less sensitive to slight differences in particle shape and texture than was ASTM D3398. All the test methods were found to be repeatable, each having low coefficients of variation for all the aggregates tested. To evaluate the effect of particle shape and texture and mineral filler content on mix performance in permanent deformation, one natural sand ranked as average performing was selected and blended with the crushed granite in the proportion of 20 percent natural sand and 80 percent crushed granite. Asphalt-aggregate mixtures containing 4, 6, 8, and 12 percent mineral filler were designed by using the Marshall procedure and were tested in repeated shear test at constant height. Within the range of mineral filler type and contents used, results indicate that mixtures containing 100 percent crushed granite show lower accumulation of permanent strain than does an 80/20 blend of crushed granite and natural sand, and an increase in the mineral filler content of a mixture was found to decrease its accumulated permanent strain while increasing the mixture shear resilient modulus.
Comparison of Superpave and Marshall Mixtures for Low-Volume Roads and Shoulders
Authors: Habib Affan , Hossain Mustaque , Kaldate Rajesh , Fager Glenn
Published: April 2007

Superpave and Marshall mix designs using local aggregates were done to study the suitability of the Superpave mix design as compared with the Marshall mix design for low-volume roads, especially shoulders. The project site was Kansas Route 177 in northeast Kansas. Three locally available aggregates, crushed limestone and coarse and fine river sands, were used in this study. Five blends with varying proportions of coarse and fine river sands were selected. Mix samples were compacted in the Superpave gyratory compactor with the applicable number of gyrations and were compacted with the Marshall hammer by using 50 blows per face. Bulk densities of the compacted samples and maximum specific gravities of loose samples also were measured for each blend. The results show that the Superpave mix design for low-volume roads and shoulders results in lower estimated asphalt content than does the Marshall method. The required asphalt content increases as the proportion of coarse river sand increases in the mix. Superpave requirements for the voids filled with asphalt (VFA) for low-volume traffic, that is, less than 0.3 million equivalent single-axle loads, appeared to be too high. High asphalt film thicknesses were computed for the mixtures that did not meet the Superpave VFA requirements. Lowering the design number of gyrations (Ndes) for compaction of samples would result in increased asphalt requirement for the Superpave mixture with a given gradation.
Corrosion Investigation, Evaluation, and Pier Replacement Scheme for the Long Key Bridge
Authors: Moreton Alan J.
Published: April 2007

Reconstruction of U.S. Highway 1 from Miami to Key West, Florida, marked the first use of epoxy-coated reinforcing in several new bridges in Florida, including the Long Key Bridge. Since then, increasing corrosion has been found in all splash zones. The novel V-piers of the Long Key Bridge received much attention; nevertheless, the superstructure, upper parts of the V-piers, and fully submerged and cased drilled shaft foundations have no corrosion at all. In 1996, a corrosion investigation was undertaken to determine the mechanisms and rate of corrosion, develop prognoses, and evaluate various courses of action. The corrosion conditions and rate were established by on-site and laboratory analyses. Historical records provided corrosion damage with time. Chloride penetration and corrosion damage were correlated with resistivity and other observations to give a relationship between the corrosive conditions and time to initial corrosion, first cracking, and critical damage. Prognoses were developed and evaluated by life cycle cost-benefit analyses for various courses of action, from “do nothing” to full-scale replacement of the piers for a service life in excess of 75 years. The techniques developed for this project could benefit maintenance monitoring and prognoses for other structures in similar corrosive environments. Contingency plans were prepared for pier replacement with precast modified V-piers to respect both the structural configuration and the historical significance of this bridge. A temporary support system was designed for rapid removal and replacement of each pier while the structure remains open to traffic on this sole route to the Florida Keys.
Field and Laboratory Evaluation of Silica Fume Modified Concrete Bridge Deck Overlays in Ohio
Authors: Fitch Michael G. , Abdulshafi Osama A.
Published: April 2007

The properties of silica fume modified concrete (SFMC) mixes that have been used by the Ohio Department of Transportation for bridge deck overlays since 1984 were evaluated under field and laboratory conditions. The research methods included construction monitoring of 9 overlay placement projects, visual inspections of 145 decks, in-depth condition surveys of 28 decks, and testing of laboratory SFMC mixes with materials obtained from the construction monitoring projects. Notable activities included field-testing to compare the effectiveness of ground-penetrating radar and manual sounding techniques for detecting the presence of debonded/delaminated deck areas and laboratory testing of overlay bond strength specimens under direct tensile loading. Based on the information collected, it was concluded that the overall performance of SFMC overlays in Ohio through 1995 was good, with none of the existing overlays showing spalling or patching; however, instances of drying shrinkage cracking were noted. Recommendations are provided to assist in achieving optimum SFMC overlay performance.
Laboratory Investigation of Coal Wastes for Secondary Roads
Authors: Ghafoori N. , Wang L.
Published: April 2007

Presented are the results of a laboratory investigation dealing with the properties of various composites made with different proportions of preconditioned fluidized bed combustion (FBC) spent bed, pulverized coal combustion (PCC) fly ash, natural fine aggregate, and portland cement. The extent to which the proposed composites can replace currently used materials is examined, and an alternate method for rebuilding low-volume county and other secondary roads is provided. Test results show that compressive strength and linear expansion of PCC-FBC composites improved with increases in PCC fly ash content of the matrix. In addition, compressive strength increased and expansion decreased when testing conditions changed from soaked to sealed to air-dried. When a low dosage of portland cement was added, an average increase of 50 percent in compressive strength and a decrease of 35 percent in 1-year linear expansion were found.
Resilient Properties and Fatigue Damage in Stabilized Recycled Aggregate Base Course Material
Authors: Sobhan Khaled , Krizek Raymond J.
Published: April 2007

A stabilized fiber-reinforced base course material composed largely of recycled concrete aggregate with small amounts of portland cement and fly ash was subjected to repeated flexural loading to evaluate its resilient properties and progressive accumulation of fatigue damage. Cyclic load-deformation data were recorded continuously during the entire fatigue life until fracture to determine ( a) the magnitude and variation of cumulative plastic strain and dynamic elastic modulus as a function of the number of loading cycles, ( b) a range for the resilient modulus, and ( c) the effect of fiber inclusions on the dynamic material properties and rate of damage accumulation. The extent of fatigue damage was calculated as a fatigue damage index, which is based on the cumulative energy dissipated (absorbed) during cyclic loading. All beam specimens used in this experimental program contained (by weight) 4 percent cement, 4 percent fly ash, and 92 percent recycled aggregate; the fiber-reinforced specimens contained an additional 4 percent (by weight) hooked-end steel fibers. Results show that the resilient modulus in flexure varies between about 2.75 GPa (400,000 lbf/in2.) and 10.4 GPa (1.5 million lbf/in.2) and the degradation of the dynamic elastic modulus does not exceed 25 percent of the initial modulus. Miner’s Rule of linear summation of damage is applicable to unreinforced material but not to fiber-reinforced material. In general, a modest amount of reinforcing fibers was very effective in retarding the rate of fatigue damage accumulation in this lean cementitious composite.
Optimizing Multiagent, Multi-Injected Swell Modifier
Authors: Addison Marshall B. , Petry Thomas M.
Published: April 2007

Interactions of expansive clay soils with transportation facilities have caused billions of dollars of damage. In the process of determining agents and methodologies to overcome expansive clay behavior, multiple injections of chemical agents into the subgrade to modify clay behavior are most promising. A study was conducted to optimize a potassium-rich solution of four parts. The modifying solution has been injected into expansive clay subgrades with success since the early 1970s. A laboratory methodology was developed to inject specimens multiple times and to conduct swell tests. Screening tests were conducted to evaluate linear effects that each of the four constituents had on swell response through interpretation of a factorial design. Analysis of replicated tests, randomly arranged in blocks, revealed that one constituent had no effect on swell behavior. A central composite experimental design then was used to optimize the remaining constituents. The resulting response surface equation led to an optimal combination for swell abatement, confirmed during short- and long-term verification testing. The optimal blend of constituents was determined to reduce swell from 7.2 percent to 0.84 percent under injection situations simulating the field, and it was found to improve the reduction in swell by 2.6 percent compared with the original blend. In addition, XRD confirmed that modification of clay occurred. This study was unique in its use of laboratory simulation of multiple field injections and in its use of statistical analysis to minimize the number of tests needed to ensure confidence in the optimization sought.
Tensile Properties of Asphalt Overlay Geosynthetic Reinforcement
Authors: Joel Sprague C. , Allen Sam , Tribbett William
Published: April 2007

Paving fabrics have been used for many years to retard reflective cracking and to enhance waterproofing in asphalt overlays. More recently, higher-strength geosynthetics have been incorporated into asphalt overlays to provide an even higher level of crack retardation and, in some cases, waterproofing. The mechanisms that lead to the enhanced performance of reinforced overlays have been described and quantified, demonstrating that the tensile stiffness added by the reinforcement allows the crack energy to be intercepted and reoriented horizontally. Therefore, it is important to better define and more clearly specify the desired tensile stiffness and how it should be measured. A summary of overlay reinforcement theory is presented to demonstrate the importance of reinforcement tensile properties. The results of laboratory testing of various geosynthetics used for asphalt overlay reinforcement are presented. Three standard tests were compared, and consistency was not found among results. A commonly used wide-width test method (ASTM D4595) was used to characterize the full tensile behavior (force-elongation relationship) for three of the materials. These test results were used to evaluate stiffness. The selection of tensile properties with respect to material and crack orientation and asphalt strain compatibility is discussed.
Using Geogrids for Base Reinforcement as Measured by Falling Weight Deflectometer in Full-Scale Laboratory Study
Authors: Kinney Thomas C. , Stone Danielle , Schuler John
Published: April 2007

A model road was constructed in a laboratory. The road consisted of asphalt over a crushed rock base and a silty sand and gravel subbase. The silty sand and gravel were placed in a very loose state to simulate a thaw-weakened, poor-quality subbase. The water table was kept at 152 mm (6 in.) below the bottom of the asphalt. The model road was divided into three sections. A geogrid was installed at the bottom of the base course material in two of the test sections, and the third was left as a control section. A falling weight deflectometer was used to measure the dynamic response of the pavement structure. The traffic benefit ratio is defined as the expected life (equivalent single-axle loads) of one section divided by the expected life of another section. The Alaska Department of Transportation and Public Facilities asphalt pavement design procedure and the NCHRP pavement design procedure were used to compare the test sections. The results from the two procedures were very similar. By using either procedure, the life of the pavement with respect to reinforcement was on the order of 2 to 4, depending on the type of grid and the depth of base course material.
Geogrid Reinforcing of Recycled Aggregate Materials for Road Construction: Finite Element Investigation
Authors: Liu X. , Scarpas A. , Blaauwendraad J. , Genske D. D.
Published: April 2007

Economic advantages and environmental benefits encourage the use of recycled materials for road construction. Usually, however, these materials have lower stiffness and strength characteristics than typically used natural materials. Because of these inferior material properties, use of recycled aggregate materials for unbound road base construction may result in increased rutting, differential settlement, and reflective crack propagation. Placement of reinforcement between the underlying soil layer and the aggregate layer has been proposed to improve the load-carrying capacity of road bases constructed from recycled aggregate materials. To investigate the viability of such an approach, finite element analyses were performed of asphalt concrete pavements with base layers consisting of reinforced unbound recycled aggregate materials. The response of such pavements was compared with that of pavements consisting of unreinforced natural aggregates. The criteria chosen for comparison were the influence of the material characteristics of the recycled aggregate and the reinforcement on the development and speed of propagation of reflective cracking in the body of the pavement. Various combinations of reinforcement and aggregate material characteristics were simulated. It was concluded that the placing of reinforcement can reduce the speed of crack propagation into the top layer, improve load spreading in the unbound base layer, and prolong the economic life of the construction.
Benefits of Using Geogrids for Base Reinforcement with Regard to Rutting
Authors: Kinney Thomas C. , Abbott Jeannette , Schuler John
Published: April 2007

A model road, designed to represent a system weakened by spring thaw, was constructed in a test facility. The road was divided into three sections. A geogrid was installed beneath the base course in two of the test sections, leaving the third as a control section. Trafficking was done in two lanes: each lane was subjected to a different tire pressure. Rutting was measured after various amounts of trafficking. The number of cycles required to reach a given level of rutting in one section divided by the number of cycles required in another section to reach the same level of rutting is defined as the traffic benefit ratio (TBR). The TBR for reinforcement was on the order of 2 to 10 and the TBR for tire pressure was on the order of 0.5 to 7. TBRs varied depending on the type of geogrid and the thickness of the base course material.
Intersection Angle Geometry and the Driver’s Field of View
Authors: Gattis J. L. , Low Sonny T.
Published: April 2007

At a skewed-angle intersection with the acute angle to the right of a driver on the minor roadway (the approach required to stop or yield), the vehicle body may obstruct the minor-road driver’s line of sight. Body parts that may obstruct the line of sight include the door frame, a panel aft of the door, or the cargo box of a single-unit truck. If the combination of vehicle design and intersection skew angle restrict a driver’s line of sight to the right, safety may be compromised. This research project evaluated obstructions caused by the bodies of a number of vehicles. The researchers measured the angles at which drivers’ lines of sight were obstructed by the body of their vehicles. Two driving positions were used—“sit back” and “lean forward.” A 13.5-degree vision angle (with respect to a line perpendicular to the vehicle path) was selected to represent an intermediate posture between the sit-back and the lean-forward positions. With a 13.5-degree vision angle in some restrictive vehicles, the 60-degree minimum intersection angle allowed by A Policy on Geometric Design of Highways and Streets (“Green Book”) will cause the driver’s line of sight to be obstructed by the vehicle itself and offer only limited sight distance. When the acute angle is to the minor-road driver’s right, minimum angles of 70 degrees or more may be more appropriate, depending on the through-road speed.
Development and Adoption of Early AASHO Design Criteria
Authors: Hall Jerome , Turner Daniel
Published: April 2007

The conception, development, and adoption of early AASHO highway design criteria are documented. Examining the early efforts states used to select a design vehicle and develop horizontal curve design criteria illustrates why AASHO’s leadership was necessary. AASHO’s slow and somewhat haphazard criteria development, and the disparity from state to state, demonstrated the need for a national consensus in highway design parameters. AASHO’s role in providing these criteria is outlined through its initial development of policy booklets, followed by its 1954 publication of the landmark Blue Book. The processes by which nine states adopted the AASHO guidance are briefly reviewed. In several cases, the AASHO policy was embraced immediately, and in others it was accepted slowly as states clung to their independent design processes and only gradually updated their design criteria. A few simple conclusions are drawn about the development and adoption process, particularly as it may relate to tomorrow’s highway design criteria.
Traffic Flow Control in Congested Motorway Networks Using Buffers
Authors: Broeren Patrick T. W. , Westland Dirk
Published: April 2007

Around large urban areas, daily recurrent congestion in the form of queueing at bottlenecks is nowadays a normal pattern. Apart from the congestion that directly follows from the capacity deficit at bottlenecks, more and more motorways are affected by a secondary congestion problem due to blocking of motorway exits and entries by long queues that build up upstream of bottlenecks, causing delay to travelers who are not going through the bottleneck. A solution to avoid congestion-induced blockage is the construction of so-called buffer facilities. These are local widenings of the motorway by adding one or more lanes just before a bottleneck. Buffers can shorten queues by an amount that is more than proportional to the number of added lanes. In this way congestion-induced blockage can be avoided and total delay is reduced significantly. Buffers are a cost-effective way to fight motorway congestion. The principles and functioning of buffer facilities are explained. Design elements and criteria as well as calculation of buffer dimensions are considered. Attention is given to the control of traffic flow at the entrance and exit of buffers. This is demonstrated with a case study from the Netherlands.
Guidelines for Selecting Single-Point Urban and Diamond Interchanges: Nationwide Survey and Literature Review
Authors: Smith Michelle J. , Garber Nicholas J.
Published: April 2007

Metropolitan areas in the United States are experiencing a steep increase in traffic growth and traffic congestion on their urban freeways. In the past, the most prevalent type of urban interchange has been the diamond interchange (DI). In more recent years, however, to overcome the need for significant additional right-of-way that is generally required for this type of interchange and still respond to increased traffic demand, a new type of interchange has emerged: the single-point urban interchange (SPUI). Traffic engineers do not agree about the relative operational efficiency of the SPUI compared with the DI. Also, the unfamiliar geometry and operation of the SPUI and its large, uncontrolled conflict area have raised several concerns about the safety of motorists who travel through it. The purpose of this study was to evaluate and compare the safety and operational characteristics of the SPUI and DI and to develop guidelines that identify traffic and geometric conditions that favor one over the other. We surveyed state traffic engineers across the nation about their experiences and opinions of the two interchanges in terms of operational performance and safety. A complete literature review on the subject revealed significant findings as well. We used both of these sources of information to develop guidelines to aid traffic engineers in selecting and designing the appropriate type of interchange.
Mainstreaming Intermodal Freight into the Metropolitan Transportation Planning Process
Authors: Zavattero David A. , Gerald Rawling F. , Rice Daniel F.
Published: April 2007

The Chicago Area Transportation Study (CATS), as a metropolitan planning organization, developed an approach to integrate intermodal freight transportation into regional plans and programs. This process began with the establishment of the Intermodal Advisory Task Force (IATF) in 1994 and led to a series of freight-oriented activities and products, including the identification of regionally significant facilities, analysis of improvement needs, and the intermodal component of the 2020 Regional Transportation Plan (RTP) for northeastern Illinois. Task Force membership includes public- and private-sector representatives working cooperatively to develop and direct a work plan to address goods movement and inter-modal freight issues and needs. The intermodal planning process involved significant preparatory work. The IATF established four working groups that directed specific tasks, including development of a geographic information system–based intermodal facilities inventory, an outreach for industry needs, a review of proposed intermodal improvements, identification and analysis of intermodal connections to the national highway system, and analysis to estimate the economic value of the industry to the region. Ultimately, six policy statements were developed and incorporated as system-level intermodal recommendations in the RTP. The process developed by CATS through the IATF has “mainstreamed” intermodal freight issues, analysis, and policies into the transportation plans and programs of northeastern Illinois. Although the scale of the intermodal and freight industry in Chicago is enormous, the lessons learned and the technical and institutional approaches developed through the IATF offer valuable insight and direction to other regions seeking to support their intermodal freight industry through the transportation planning process.
Freight Planning Typology
Authors: Souleyrette Reginald , Maze T. H. , Strauss Tim , Preissig David , Smadi Ayman G.
Published: April 2007

A layered architecture for freight transportation demand modeling entails the construction of a statewide freight transportation demand model by separately simulating traffic for one commodity at a time. Layers can then be added together to construct a comprehensive model that includes the most significant freight flows. Most state or regional economies are dominated by a few economic sectors, and models can be constructed for those sectors that generate the most freight traffic and/or are the most important to the regional economy. Freight traffic demand modeling in intercity applications is more likely to focus on economic development, local infrastructure improvements, maintenance, and similar policy and planning concerns than on system capacity issues. Thus, it is more important to understand changes in traffic growth by economic sector than as the composite of all freight traffic. This method is less data intensive and more easily understood by transportation professionals than previous approaches. The layered approach is therefore more likely to achieve the desired objectives than would general models, which attempt to forecast heterogeneous freight transportation demands simultaneously. This approach is demonstrated through a case study using the meat products and farm machinery industries in Iowa. Other commodities will be added in the future to complete a model of Iowa’s statewide freight transportation demand. A framework is presented for organizing and identifying planning goals, key issues, and predominant commodities for intercity freight transportation. Although examples are provided, specific recommendations addressing the full range of issues, data collection activities, tools, and urban applications are suggested for further study. A case study demonstrates the approach used for one issue, one mode, and two commodities, which could be repeated elsewhere for similar applications.
Incorporating Freight Issues into Baltimore’s Regional Transportation Planning Agenda: Progress to Date and Lessons Learned
Authors: Plumeau Peter , Jones Jocelyn
Published: April 2007

Strategically located midway along the East Coast, the Baltimore region has one of the nation’s most sophisticated intermodal freight and goods movement systems, consisting of an extensive highway system, two Class I and several smaller railroads, an international airport, and a major deepwater seaport. Further, thousands of firms in the Baltimore region are engaged in the handling and transporting of freight. A heightened awareness of the region’s freight movement needs and issues, combined with the Intermodal Surface Transportation Efficiency Act’s emphasis on intermodal transportation planning, resulted in the Baltimore metropolitan planning organization’s (MPO’s) designation of a public-private Freight Movement Task Force to work with MPO staff to provide guidance and advice on freight-related transportation issues and needs. As the Baltimore MPO pursued its aggressive freight movement planning agenda, it was recognized that addressing freight needs and issues would require MPO members and staff to assume roles and pursue transportation planning activities in markedly different ways than they had been pursued traditionally. An examination of the MPO’s efforts to incorporate freight movement issues into the regional transportation planning agenda is provided, with a discussion of the MPO’s progress to date, how various challenges were addressed and overcome, freight planning products developed, and lessons learned from this undertaking that may be instructive to other transportation planning agencies as they venture into the freight planning arena.
Urban Freight Mobility: Collection of Data on Time, Costs, and Barriers Related to Moving Product into the Central Business District
Authors: Morris Anne G. , Kornhauser Alain L. , Kay Mark J.
Published: April 2007

Just-in-time deliveries and lower inventories have led to more frequent deliveries of goods and services, markedly increasing urban congestion. The Goods Movement in the New York Metropolitan Area study’s goal was to develop a research methodology for capturing urban freight mobility data and to collect cost and time data on freight moving into New York City’s central business district (CBD). The methodology developed and its implementation are discussed. Problems with access and collecting data from industry executives are also addressed. In industry-sector focus groups, senior logistics executives discussed urban freight mobility issues, especially barriers to goods movement into the CBD. Barriers consistently identified in order of greatest frequency of mention from 13 focus groups were congestion, inadequate docking space, inadequate curb space for commercial vehicles, security, and excessive ticketing of high-profile companies. The Freight Mobility Interview form asked logistics/transportation/distribution managers to provide company-specific information about the following categories: transportation services and distribution channels used and related cost, time, and barriers to freight mobility. Analysis of the interview data revealed that major barriers to freight mobility identified by both shippers and carriers were consistent with those cited by focus group participants. The combined qualitative and quantitative data collected identified the processes industry uses to manage urban congestion.
Impact of Size and Weight Regulations on Trucks Crossing the Canadian-U.S. Border
Authors: Nix Fred P. , Billing John R. , Delaquis Michèle
Published: April 2007

The conventional view is that U.S. federal limits govern trucks operating across the Canadian-U.S. border. The identification of 118 roads crossing the border and a description of the regulations in neighboring provinces and states governing traffic on them are provided. Surveys at 25 crossings that carry 87 percent of cross-border truck traffic have identified truck configurations in different regions. The standard fiveaxle tractor-semitrailer, at a gross vehicle weight of up to 36 287 kg (80,000 lb), is the principal truck used between the two countries, but mainly for low-density freight or long hauls. Almost 22 percent of trucks crossing the border are configured to carry payloads heavier than possible with this truck. Most have at least six axles, and many make use of liftable axles. Local cross-border trucking operations are making significant use of trucks larger and/or heavier than those allowed under U.S. federal regulations and under provincial and state regulations, grandfather rights, or permits.
Some Measures to Improve Safety of Road Motor Transport in Mexico
Authors: Mendoza Alberto , Chavarría Jesús M. , Mayoral Emilio
Published: April 2007

Several statistics concerning the occurrence of accidents on the most important fraction of the Mexican highway system (basic network) are given. The involvement of cargo trucks in these accidents is discussed. The factors that contribute most to the occurrence of accidents are identified. Among these factors, those related to the speed of the vehicles that make up the traffic flows stand out. An economic analysis to determine the optimum speed limits and highway design speeds is provided. This analysis is based on depicting, for a given road section, the trend of vehicle operating costs (VOCs), accident costs, and the sum of both with respect to speed. The trend of accident costs is determined from assessment of the average cost per accident in the basic network and prediction of the variation of accident rate with respect to mean flow speed. The VOC trend is obtained by using the World Bank VOC model, calibrated for Mexican conditions. Some recommendations for improving existing speed laws and the enforcement of the regulating system are presented. Other actions for generating a national road safety program are mentioned.