Michael Anderson

SERVICEABILITY INDEX TO EVALUATE RURAL DEMAND-RESPONSIVE TRANSIT SYSTEM OPERATIONS

Recently, focus on the analysis of public transit systems has been increasing. The Transit Capacity and Quality of Service Manual consolidates information on current practices. By stating that no national studies support transit capacity analysis for demand-responsive operations, the manual identifies an inability to estimate capacity and level of service for agencies that provide demand-responsive transit. A procedure for calculating a serviceability index (SI) for demand-responsive transit operators based on regional socioeconomic conditions and internal operation data is presented. The methodology results from a survey of several demand-responsive transit providers in Alabama and data analysis. A case study for two counties served by the Northwest Alabama Council of Local Governments transit agency illustrates the SI calculation to identify benefits and drawbacks. Generated with input from transit providers, SI can be used to evaluate and compare demand-responsive transit operation.

Direct Demand Forecasting Model for Small Urban Communities Using Multiple Linear Regression

Forecasting traffic volumes to support infrastructure decisions is the heart of the travel demand modeling process. The most commonly used methodology for obtaining these forecasted traffic volumes is the four-step process that considers generation, distribution, mode choice, and route assignment of trips. Each step of the process is performed independently, almost always through the use of computer software, to achieve the final traffic volumes. This paper examines the possibility of forecasting traffic volumes by using a multiple linear regression model to perform what is termed direct demand forecasting. The direct demand forecasting model generates traffic volumes for roadways through the development of a functional relationship between roadway characteristics and socioeconomic influences. A direct demand travel forecasting model has been developed and applied, with a small urban area as a case study community. Results are consistent with those obtained from the traditional four-step methodology.

Pseudo-Dynamic Travel Model Application to Assess Traveler Information

This paper reports an effort to estimate potential benefits of Advanced Traveler Information Systems (ATIS) by combing regional travel demand and microscopic simulation models. The approach incorporates dynamic features not yet available in the commercial software market. The suggested technique employs data that are readily available to most urban planning organizations, and is straightforward in its application. The key reported measure of effectiveness is corridor and local system delay, and is sensitive to both the level of penetration of traveler information and the pre-trip and en-route choices drivers make based on this information. The technique is demonstrated on an urban freeway corridor in a medium sized mid-west city.

Development and Application of a Vehicle Procurement Model for Rural Fleet Asset Management

Advanced asset management systems have emerged as important tools in the management, maintenance, and procurement of vehicles for transit fleet operators. Effective design and use of an asset management system can increase productivity, enhance public perception, and provide a consistent basis for decision making and planning. This paper documents the design and application of a vehicle procurement model in an asset management system created for the Alabama Department of Transportation to manage vehicles purchased and operated through the Section 5311 federal grant program. The vehicle procurement model predicts future vehicle serviceability, or condition rating, by using a combination of factors, including service area socioeconomic data and vehicle usage data. Application of the system helps transportation professionals estimate the overall fleet quality, identify vehicles that will need to be replaced each year, aid in the management of vehicles, and provide a basis for predicting future funding and budgetary needs.

Issues, Practices, and Needs for Communicating Evacuation Information to Vulnerable Populations

Effective communication of transportation-related information to vulnerable populations is a critical need during emergencies. Despite its importance, various factors still hinder the development of comprehensive and effective plans for communicating emergency information to mobility-limited individuals during evacuations and other major emergencies. Such limiting factors include the wide diversity of vulnerable populations, their special needs, existing contact and communication barriers, and lack of resources and mechanisms to locate those populations and assist them during emergencies. This paper illustrates the complexity of communicating with vulnerable populations in emergency evacuations through a critical review of the existing literature and state-of-the-practice information gathered recently from transportation and emergency management agency personnel. First, the paper reviews definitions, characteristics, and size of the vulnerable population. Next, principles of effective communication and the special provisions for communicating with vulnerable populations are presented, along with examples of effective communications and communications barriers. Finally, the paper identifies numerous important emergency evacuation communications topics that were not discussed in the literature and offers recommendations for bridging those gaps. Examples include the limited involvement of experts in emergency evacuation communication, the lack of information about the financial aspects and cost-effectiveness of such communications, the need to establish an information clearinghouse to assist in future evacuations, and the lack of standardization and cataloging of appropriate evacuation messages. The paper is presented as a foundation for developing a framework for effective communications strategies, policies, and practices that focus on vulnerable populations before, during, and after all-hazards emergencies.

Spatial Economic Model for Forecasting the Percentage Splits of External Trips on Highways Approaching Small Communities

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 we...

A Simulation Optimization-Based Decision Support Tool for Mitigating Traffic Congestion

Traffic congestion has grown considerably in the United States over the past 20 years. In this paper, we develop a robust decision support tool based on simulation optimization to evaluate and recommend congestion mitigation strategies to transportation system decision-makers. A tabu search-based optimizer determines different network design strategies on the road network while a traffic simulator evaluates the goodness of fit. The tool is tested with real-world traffic data.

Using Aggregated Federal Data to Model Freight in a Medium-Sized Community

In most urban areas, freight volumes are not explicitly considered in the transportation planning process. This is primarily due to the proprietary nature of freight data, causing any freight data that are released to be highly aggregated. This paper examines a multitiered methodology to utilize freight data from a federally available, highly aggregated source within an urban planning model to accurately model truck transportation. A case study is included that demonstrates the modeling methodology for a medium-sized urban area, complete with international port, and contains validation results of the freight transportation in the area.

DYNAMIC TRIP GENERATION FOR A MEDIUM-SIZED URBAN COMMUNITY

Traditional transportation modeling activities in medium-sized urban communities follow the four-step planning process: trip generation, trip distribution, mode split, and traffic assignment. These models forecast daily traffic volumes on major roadways of the communities to support infrastructure investment decisions. Recently, researchers have focused on dynamic traffic-assignment models, which provide time as a measure in the trip-modeling process, to support incident management and intelligent transportation system–based decisions. As a methodology to support the dynamic traffic-assignment models, development of a dynamic trip-generation model for a medium-sized urban community is considered. An overview of the need for dynamic trip-generation data is presented, and a methodology and a data-collection effort to develop a dynamic trip-generation model are discussed. Results are included of a validation study performed on the model. It is concluded that the models developed in the effort can provide dynamic trip-generation data and represent a first step toward making the dynamic transportation model a viable resource.

Geographic Information System-Based Transportation Forecast Model for Small Urbanized Areas

The geographic information system (GIS) has been demonstrated to be an effective tool for transportation forecasting and scenario analysis. Previous efforts have linked full-function GIS packages with transportation forecasting models. Tools developed to provide a modeling environment more appropriate for the technical knowledge level and budget requirements of small urban or rural areas are described. Specifically, the needs of metropolitan planning organizations and regional planning affiliations in Iowa were considered in the system design. A desktop mapping package, MAPINFO, is integrated with an urban transportation planning model, TRANPLAN, to provide an interface for network analysis. With the system, network modifications and changes representing alternative demand scenarios are made in the GIS environment, and data are exported to the TRANPLAN format, and, after analysis, returned to the GIS for effective presentation of results. User tools were tested and a case study demonstrating alternatives analysis and display capabilities is presented. Although developed and tested for Des Moines, the system can easily be transferred to other agencies to enhance transportation planning capabilities.