44 research outputs found

    Freeway Service Patrols: A Stated Preference Analysis of Insurance Values

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    Highway assistance services, also called the freeway service patrols (FSPs), are one of the main approaches used by incident management programs. The objective of this study was to investigate the factors that contribute to people choosing to rely on the highway assistance services (FSP) in comparison to private assistance services such as the Automobile Association of America (AAA). Further the effectiveness of the Freeway Service Patrol was studied by carrying out a Benefit-Cost Analysis using Los Angeles as a test case. The results indicate that the probability that an individual would choose to depend on the highway assistance services depends on the key attributes like the annual fee of the program, the fee at the time of assistance, the time of waiting for assistance and cost of breakdown. The B/ C ratio for the Los Angeles FSP was calculated to be 5.91.Freeway Service Patrols, Evaluation, Insurance, Mobility.

    Post-Construction Evaluation of Traffic Forecast Accuracy

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    This research evaluates the accuracy of demand forecasts using a sample of recently-completed projects in Minnesota and identiÞes the factors inßuencing the inaccuracy in forecasts. The forecast traffic data for this study is drawn from Environmental Impact Statements(EIS), Transportation Analysis Reports (TAR) and other forecast reports produced by the Minnesota Department of Transportation (Mn/DOT) with a horizon forecast year of 2010 or earlier. The actual traffic data is compiled from the database of traffic counts maintained by the Office of Traffic Forecasting and Analysis section at Mn/DOT. Based on recent research on forecast accuracy, the (in)accuracy of traffic forecasts is estimated as a ratio of the forecast traffic to the actual traffic. The estimation of forecast (in)accuracy also involves a comparison of the socioeconomic and demographic assumptions, the assumed networks to the actual in-place networks and other travel behavior assumptions that went into generating the traffic forecasts against actual conditions. The analysis indicates a general trend of underestimation in roadway traffic forecasts with factors such as highway type, functional classiÞcation, direction playing an inßuencing role. Roadways with higher volumes and higher functional classiÞcations such as freeways are subject to underestimation compared to lower volume roadways/functional classiÞcations. The comparison of demographic forecasts shows a trend of overestimation while the comparison of travel behavior characteristics indicates a lack of incorporation of fundamental shifts and societal changes.Minnesota, Minneapolis, Travel Demand Model, Transportation Planning, Forecasting

    The Influence of Network Structure on Travel Distance

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    The objective of this research is to identify the role of network architecture in influencing individual travel behavior using travel survey data from two urban areas in Florida: Fort Lauderdale and Miami. Various measures of network structure, compiled from existing sources, are used to quantify roadway networks, capture the arrangement and connectivity of nodes and links in the networks and the temporal and spatial variations that exist among and within networks. The results from the regression models estimated show that network design influences how people travel and make decisions. Results from this analysis can be used to understand how changes in network can be used to bring about desired changes in travel behavior.Network structure, travel behavior, transport geography, commuting, circuity

    Accessibility Futures.

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    This study uses accessibility as a performance measure to evaluate a matrix of future land use and network scenarios for planning purposes. Previous research has established the coevolution of transportation and land use, demonstrated the dependence of accessibility on both, and made the case for the use of accessibility measures as a planning tool. This study builds off of these findings by demonstrating the use of accessibility-based performance measures on the Twin Cities Metropolitan Area. This choice of performance measure also allows for transit and highway networks to be compared side-by-side. A zone to zone travel time matrix was computed using SUE assignment with travel time feedback to trip distribution. A database of schedules was used on the transit networks to assign transit routes. This travel time data was joined with the land use data from each scenario to obtain the employment, population, and labor accessibility from each TAZ within specified time ranges. Tables of person- weighed accessibility were computed for 20 minutes with zone population as the weight for employment accessibility and zone employment as the weight for population and labor accessibility. The person-weighted accessibility results were then used to evaluate the planning scenarios. The results show that centralized population and employment produce the highest accessibility across all networks.Accessibility, Forecasting, Travel Demand, Scenarios, Trends, Transportation, Land Use.

    The Importance of Being Early

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    The assumption that the penalty for being early is less than that for being late was put forward by Vickrey (1963) who analyzed how commuters compare penalties in the form of schedule delay (due to peak hour congestion), against penalties in the form of reaching their destination (ahead or behind their desired time of arrival). This assumption has been tested by many researchers since then for various applications, especially in modeling congestion pricing (Arnott et al., 1990) where it is critical to understand the tradeoff between schedule delay and travel delay. Key findings are summarized in the second section of this paper. This research aims to test this hypothesis of earliness being less expensive than lateness using empirical data at different levels and across different regions. New methods to estimate the ratio of earliness to lateness for different types of datasets are developed, which could be used by agencies to implement control policies like congestion pricing or other schemes more accurately. Travel survey data from metropolitan areas provide individual travel patterns while loop detector data provide link level traffic flow data.Schedule Delay, Travel Time, Traffic, Travel Behavior.

    Network structure and metropolitan mobility

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    This research aims to develop quantitative measures that capture various aspects of the underlying network structure, using aggregate level travel data from fifty metropolitan areas across the US. The influence of these measures on system performance is then tested using statistical regression models. The results corroborate that the quantitative measures of network structure affect the system performance. The results from this analysis can be used to develop network design guidelines that can be used to address current transportation problems
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