Timothy J Lomax

• Texas A&M University

Transportation performance measures based on travel time quantities satisfy a range of mobility purposes. The measures can show the effect of many transportation and land use solutions, and they are relatively easy to communicate to a range of audiences. The concept of total travel time has been discussed since the early 1950s, but because of data...

The concept of a congestion threshold is embedded in the definition of "congestion." Two basic approaches exist in current practice for setting the congestion threshold. One common approach uses the free-flow or unimpeded conditions. Another approach uses a variety of targets or acceptable conditions. The limited research conducted on the congestio...

DISCLAIMER The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. This document is disseminated under the sponsorship of the Department of Transportation University Transportation Centers Program, in the interest of information exchange. The U.S. Governme...

This paper presents a GIS-based procedure to estimate congestion index (CI) at the highway link level. Using the 1995 traffic assignment data for the Lubbock, TX area, the exercise produces CI values at the network link level. These disaggregate measures of CIs are then presented in two summary forms. One is the statistical summary of aggregating l...

This report documents roadway congestion and mobility measures in 70 major urban areas in the United States. This study contains vehicle travel, facility length and operation estimates, and urban area characteristics from 1982 to 1996 for each of these urban areas. Various federal, state, and local agencies provided the information used to update a...

A congestion index that is keyed to the differences in actual versus desired travel times for various types of roadways is described. The suggested index provides a continuous scale for assessing the amount of congestion incurred. It encompasses a wide range of values and is easy to understand and use.

Procedures are presented for measuring and estimating roadway congestion levels. An assessment of users, uses, and audiences indicates a need for congestion measures that are understood by nontechnical audiences, yet are rigorous enough for technical analyses. Travel time-based measurements are deemed most useful for this wide range of needs. Data...

Measuring the effects of transportation system improvements has long been a challenge. Two estimates - the congestion index method and the travel delay method - are used to produce a range of possible benefits resulting from the implementation of transportation projects and programs. The congestion index method uses the roadway congestion index (RC...

Transportation systems analyses have been evolving as the decision context for improvement projects and programs has changed. The increased emphasis on the movement of persons and goods, and a recognition of the importance of system performance measures that address the needs and interests of the audiences for mobility information, will result in a...

Measuring the effects of transportation system improvements has long been a challenge. Two estimates—the congestion index method and the travel delay method—are used to produce a range of possible benefits resulting from the implementation of transportation projects and programs. The congestion index method uses the roadway congestion index (RCI),...

A congestion index that is keyed to the differences in actual versus desired travel times for various types of roadways is described. The suggested index provides a continuous scale for assessing the amount of congestion incurred. It encompasses a wide range of values and is easy to understand and use.

Procedures are presented for measuring and estimating roadway congestion levels. An assessment of users, uses, and audiences indicates a need for congestion measures that are understood by nontechnical audiences, yet are rigorous enough for technical analyses. Travel time–based measurements are deemed most useful for this wide range of needs. Data...

Transportation systems analyses have been evolving as the decision context for improvement projects and programs has changed. The increased emphasis on the movement of persons and goods, and a recognition of the importance of system performance measures that address the needs and interests of the audiences for mobility information, will result in a...

A summary of the state of the practice related to the design of cross sections for high-occupancy-vehicle (HOV) lanes on freeway and arterial streets is presented. This summary is based on several documents including an AASHTO design guide. The current guidance is in the from of a set of issues that should be addressed before an arterial street tre...

A procedure was developed to estimate the relative traffic congestion levels on urban-area roadway systems. The data elements of the methodology are available from planning agencies and are based on an urban-area designation rather than specific political boundaries. The methodology can be utilized by agencies in urban areas that rely on the freewa...

The range of transitway (barrier-separated, reversible, one-lane HOV) design specifications makes the design of transitways difficult in itself; the restricted right-of-way and need for complementary highway improvements further hinder design flexibility. Engineering judgments must be made as to compromises in both transitway and highway configurat...

This study involved the development of an index of transit service availability (ITSA). This index utilizes the factors which most effectively quantify the availability of public transit service (both bus and rail) in an urban area at a macroscopic planning level. The development of the index consisted of applying over 30 prospective measures of tr...

This research report represents the seventh year of a ten-year research effort focused on quantifying urban mobility. This study contains the facility information for 50 urban areas throughout the country. The database used for this research contains information on vehicle travel, system length, and urban area characteristics from 1982 to 1992. Var...

The Dallas Freeway/High-Occupany Vehicle Lane System Planning Study is a joint project in cooperation with the Texas Department of Transportation (TxDOT), Dallas Area Rapid Transit (DART), the North Central Texas Council of Governments (NCTCOG), and the Texas Transportation Institute (TTI). The intent of this effort is to assist in the development...

Over the past two decades there has been an increasing awareness of the need to develop a more energy efficient transportation system. This research explored the relationship between energy efficiency and transportation by analyzing the relationship between energy efficiency and specific aspects of transportation. This research analyzed the relatio...

This research report represents the seventh year of a ten-year research effort focused on quantifying urban mobility. The study contains the facility information for 50 urban areas throughout the country. The database used for this research contains information on vehicle travel, system length, and urban area characteristics from 1982 to 1992. Vari...

This study was sponsored by the Texas Department of Transportation (TxDOT) as part of an effort to identify a balanced transportation system for the future in the Dallas area. The system should accommodate the projected travel demand at the lowest public cost. The mission of the study is to provide an intermediate planning step between the macrosco...

The study affirms that urban public transit systems in Texas provide an alternative to the private automobile in 18 urban areas and generate significant benefits to the users, communities served and the Texas economy. The purpose of the study was to examine the role of urban public transit systems in Texas and associated cost and benefits of transi...

The research report studied 39 urban areas. An assessment of the freeway and major street operating conditions was performed in seven Texas and 32 other urban areas in the continental United States. In addition, the analyses from 1982 to 1986 were updated to include 1987 urban area data. Vehicle-miles of travel and lane-miles of roadway data were c...

District offices of the Texas State Department of Highways and Public Transportation have sponsored research into high-occupancy vehicle (HOV) lane-cost effectiveness in Houston, Dallas and San Antonio. This report documents the process used to derive guidelines for estimation of HOV lane project benefit/cost ratios. An extensive radial freeway FRE...

1. Intersections with a high number of crashes were selected for the installation of a red light camera (RLC) based on crashes reported for the years 2000 thru 2005. 2. One approach per intersection was selected for the installation of a red light camera. From an 8-hour trial period, the selected approach was determined to have the highest rate of...

The Texas Transportation Institute's Urban Mobility Report has provided an easy-to-understand view of urban transportation congestion issues for nearly 20 years. In recent years, operational treatments, high-occupancy-vehicle lanes, and public transportation facilities have been incorporated into the study to include the effects of these treatments...

Typescript (photocopy). Thesis (Ph. D.)--Texas A & M University, 1987. Vita. Includes bibliographical references (leaves 70-75). "Major subject: Civil Engineering."