查看更多>>摘要：For decades, Dutch transport policies have been dominated by two themes: congestion and environment. Extensive research has revealed planning concepts that can improve the performance of transportation networks and reduce the environmental impact of traffic and transport by using spatial planning policies. Such concepts were introduced in the Dutch policy realm with little success, and there remains a lack of cooperation between the fields of traffic and transport and spatial planning and between various levels of government—at the cost of accessibility and the environment. The recent shift in Dutch traffic and spatial policies to decentralize power and policy implementation from the national to the regional level might encourage regional transport and spatial planners to integrate the policy realms toward cooperation or even to collaboration. This article describes the design of training for transport engineers and spatial planners to improve their abilities to cooperate successfully and to work more effectively on the regional themes of accessibility and environmental impact. The training focuses on projects that can be characterized as cross-boundary cooperation. The training is based on the theories and practices of the learning organization and on a constructivist perspective on learning.
Seongsoon YunWade W. WhiteDaniel R. LambYongqiang Wu...
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查看更多>>摘要：Truck traffic accounts for a substantial fraction of the traffic stream in many regions and is often the source of localized traffic congestion. This paper presents the analysis and findings that recommend updated volume-delay relationships for transportation planning models that account for total volume, roadway capacity, and the mix of heavy truck traffic. The traditional Bureau of Public Roads function representing the speed-flow relationships for roadway facilities is modified to include the impact of truck traffic specifically. Several new speed-flow functions based on microsimulation results for freeways and urban arterials have been developed.
查看更多>>摘要：Discrete choice modeling techniques have been used to model simultaneously the effects of land use and socioeconomic and demographic characteristics on travel behavior. To evaluate the performance of destination choice models with aggregate alternatives at the level of the travel analysis zone in allocating trips between zone pairs, this study developed three sets of home-based work models by using data collected from Broward, Palm Beach, and Volusia Counties in Florida. An objective for this study was to identify the benefit of destination choice models to urban areas of different sizes and characteristics. The spatial distribution patterns from the models were compared with those obtained from gravity models. The results from this study show that all urban areas benefited from destination choice models regardless of the urban size.
查看更多>>摘要：The Commute Atlanta program is an instrumented vehicle research program funded by the FHWA Value Pricing Program and the Georgia Department of Transportation. A major objective for the multiyear program is to assess the effects of converting fixed automotive costs into variable driving costs. The main research hypothesis is that given a per mile pricing system, participants will modify their driving patterns in an effort to reduce their total costs, pocketing the savings. The Commute Atlanta project includes the parallel collection of instrumented vehicle data, household sociodemographic surveys, 2-day travel diaries, and employer commute options surveys. The research team will monitor the changes in driving patterns and will use statistical analyses of household characteristics, vehicle travel, and relevant employer survey data to examine the relationships between the incentives offered and subsequent travel behavior changes. This paper focuses on the recruitment methods and travel diary response rates for the 2-day diary surveys conducted in February and March 2004. As in other instrumented vehicle studies, researchers collected data that allow the comparison of reported diary travel with monitored vehicle travel. However, this paper focuses on a new type of comparison. Because the households had been recruited into the study 8 months before the diary study and their vehicles were transmitting activity data, the research team could examine whether there were differences in household vehicle activity between that 77% of households that completed the diary data collection and the 23% that did not. The differences were significant at both the high and low ends of the travel-reporting spectrum and may have some major implications for evolving household travel survey methods.
查看更多>>摘要：There is a large gap between the aggregate, trip-based models used by transportation planning agencies and the activity-based, microsimu-lation methods espoused by those at the forefront of research. The modeling environment presented here is intended to bridge this gap by providing a palatable way for planning agencies to move toward advanced methods. Three components to bridging the gap are emphasized: an incremental approach, a demonstration of clear gains, and a provision of an environment that eases initial implementation and allows for expansion. The modeling environment (called STEP2) is a household microsimulator, developed in TransCAD, that can be used to implement a four-step model as well as models with longer-term behavior and trip chaining. An implementation for southern Nevada is described, and comparisons are made with the region's aggregate four-step model. The models perform similarly in numerous ways. A key advantage to the microsimulator is that it provides impacts by socioeconomic group (essential for equity analysis) and individual trip movements (for use in a vehicle microsimulator). A sensitivity analysis indicates that the microsimulation model has less inelastic cross elasticity of transit demand with respect to auto travel times than the aggregate model (aggregation error). The trade-off is that microsimulators have simulation error; results are presented regarding the severity of this error. This work shows that a shift to microsimulation does not necessarily require substantial investment to achieve many of the benefits. One of the greatest advantages is a flexible environment that can expand to include additional sensitivity to demographics and transportation policy variables.
查看更多>>摘要：Values associated with statewide freight and tourist mobility; traffic, pedestrian, and bicycle safety; and small-town Inability create competing objectives that are difficult to balance when main streets of small towns are also state highways. Many communities opt for bypass solutions to these issues, but the Philomath Couplet Project represents a main street solution that is sensitive to both the demands of the state highway system and the character of the local community. The controversial 10-month decision process culminated in the selection of a preferred alternative. Final design is under way, and construction is scheduled for 2006. Although many projects are developed according to context-sensitive solution principles, the Philomath Couplet Project represents a class of projects with characteristics likely to be faced throughout the United States in relation to the management of state highways that are also main streets of small towns. The difficulties encountered in conducting this project provide important insights to guide context-sensitive solutions implementation in these circumstances. The lessons learned shared in this paper highlight the need to manage the "end game" of small-town politics, the value of time and cost constraints, the need for a structured decision process, and the usefulness of evaluation criteria based on interactions of land use and transportation.
查看更多>>摘要：What began as compliance with the federal mandate for consultation with nonmetropolitan officials is evolving in Arizona into an enthusiastically embraced opportunity to build positive relationships between state, regional, and local jurisdictions. This case study in the implementation of this federal requirement shows how the process provides a meaningful opportunity for local officials to offer input into transportation planning and programming. The study also demonstrates the role of the consultation process in establishing trust and cooperation on the part of local governments and in developing greater understanding of local needs on the part of state transportation agencies.
查看更多>>摘要：Creating an effective public involvement process in transportation planning and project development is a challenge for transportation agencies. A meaningful and timely consultation process is especially challenging in projects that affect the cultural resources of Native American tribes. An overview is presented of the major legislative requirements for Native American involvement in federal transportation projects. Three case studies—from Georgia, Wisconsin, and New York—examined how states have effectively streamlined involvement with Native American nations in the transportation decision-making process. Although every transportation program is different and each approach to public involvement should be tailored to project-specific needs, many issues of the consultation process with Native American governments are the same across state transportation agencies. This paper presents how the studied states addressed these issues to improve consultation with Native American governments. Challenges discussed include how overloading tribes with information results in less feedback, the difficulties in ratifying memorandums of understanding to streamline the process, overcoming the lack of trust, dealing with different ways of doing business, dealing with out-of-state tribes, and the difficulties in working agreements on the ownership of artifacts. Much information can be applied by other states to improve and streamline their consultation processes with Native American governments.
查看更多>>摘要：The main difficulty in forecasting traffic volumes in small urban communities is identifying the amount and destination of the external traffic. Three methods exist for determining the percentage of external traffic destined for the study community (external-internal trips) or through the study community (external-external trips): a comprehensive origin-destination study, a cordon line origin-destination study, and the use of regression equations. This paper examines the possibility of the use of an alternative technique, based on a spatial economic model, to determine the traffic distribution. The project uses an economic model, which includes surrounding community factors, to determine the trip rates for three communities within Alabama and compares the results obtained from this model with the results given by a commonly accepted regression equation and a recently completed cordon line origin-destination study performed by using video surveillance. It is demonstrated that the economic model performs well for the case study cities, and this model is recommended for use in providing estimates that incorporate a community's economic relationship to neighboring towns for traffic forecasting.
查看更多>>摘要：The capital budgeting process for a transportation system is usually complicated by the interdependencies of projects and the uncertainty of project costs. The existence of project interdependence in transportation systems makes it difficult to evaluate the project effects with analytical methods. Furthermore, when the construction costs of candidate projects are uncertain, the budget constraints that bind project selection become chance constraints, and this may render most existing approaches inapplicable. This paper formulates the project selection problem as a nonlinear integer optimization problem whose objective function is implicit but can be evaluated with network simulation. The Lagrangian method is applied to relax the complex project constraints that are nonlinear under cost uncertainty. An efficient genetic algorithm is developed to solve the Lagrangian subproblems. This paper applies an equilibrium traffic assignment model to evaluate the project impacts and the objective values of the Lagrangian subproblems. Experiments are designed to test the performance of the developed approach on a fairly generic highway system. The experiment results show that the developed approach can effectively solve the problem of selecting interdependent projects under cost uncertainty.
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