This project recognizes the disparity in the relationship between truck and passenger car speeds and current advisory speed-signing practices. The results of this project provide a mechanism that traffic engineers may use to provide enhanced differential warning to trucks and passenger vehicles at freeway connector ramps. The strong evidence of a significant differential between the speeds that cars and heavy trucks can comfortably and safely traverse freeway connector ramps or loops revealed a need for further research. This research would investigate current advisory speed-signing practices and examine whether a dual-advisory speed-signing scheme, one that provides different recommended advisory speeds for trucks and passenger vehicles, can safely address this differential. On the basis of the results of the analysis of average and 85th-percentile speeds at the midpoint of each study curve, the dual-advisory warning signs had a positive impact on reducing speeds at the point of curvature on the curve and had an accompanying reduction in speed-related crashes at the study sites, or both.

The goal of the access management study of the Houston–Galveston Area Council in Texas, was to examine the effects of recommended improvements before, during, and after project implementation in three areas: operations (traffic flow, intersection delay, and corridor delay), safety (crash frequency, crash rates, and comparisons with state averages), and economic (comparison of taxable sales receipts and control for other economic factors occurring during those times). This paper focuses on an economic assessment that was not addressed by previous studies and on local concerns about the economic impacts of access management. This economic evaluation methodology focused on collection and analysis of taxable sales data to examine possible changes in business activity before, during, and after any implemented access management improvements for various classes of businesses in the corridor study areas. Three corridors, consisting of principal arterials in a large urban area with retail and residential development, were studied. The trends from the three corridors studied suggested that business sales increased at a greater rate along these corridors than in the adjacent control zip code analysis zone. The data showed that overall economic activity in the three corridors was not negatively affected by the implementation of access management. Although confounding factors (Hurricanes Rita and Ike and the economic recession of 2007 to 2009) were in play in an examination of economic impacts during these types of projects, the results of this evaluation indicated that corridor economic activity typically remained steady, and in many cases, increased after access management projects were implemented.

This paper presents an evaluation of the use of lighted pavement markers parallel to an intersection stop bar for three treatment intersections in Houston, Texas. The line of pavement markers was active, with a red light displayed from each marker during the red interval of the traffic signal. Each lighted pavement marker contained multiple LEDs, which operated such that each marker displayed an alternating wigwag pattern. The intended impact of the pavement markers was to reduce red light running violations and crashes on the intersection approach to an arterial that had an at-grade light rail line within its median. A before-and-after study was conducted to determine changes in crashes, red light running violations, and right turn on red violations at the study sites (right turns on red are prohibited at all the study sites). The analysis results showed that the lighted pavement markers reduced red light running violations at all three treatment sites, with two of the three reductions being statistically significant. Right turn on red violations were also reduced, and the reduction was statistically significant at all three treatment sites. A fourth site was chosen as a comparison (nontreatment) site, and the before-and-after study showed no notable change in the number of red light running violations or right turn on red violations at this site.

Several steps in the planning, execution, and evaluation of the I-45 Pierce Elevated reconstruction in Houston provide a strong framework for preparing for projects that affect critical links in the nation’s transportation system. These elements include preconstruction traffic modeling, public information, and data collection before and during each phase of construction. Traffic modeling helped to prepare for construction by first developing delay numbers for the estimated user cost used in the A + B bidding. Second, preconstruction modeling identified bottlenecks that were temporarily remediated at strategic locations. Finally, modeling provided speed and travel time data used in mounting a public information campaign. Data collection and monitoring of traffic conditions immediately before, immediately after, and a few weeks after construction began provided an immediate picture of traffic conditions and identified problem locations that could be corrected during construction. A critical public information campaign was undertaken using television, radio, newspaper articles, billboards, fliers, and variable message signs. Each of these provided advance warning to motorists in the weeks before construction began and variable message signs, radio, and the Internet were used to provide real-time information during construction. Preparations for the Pierce Elevated reconstruction went beyond standard procedures and planning typically used for major construction projects. Although engineers have traditionally been designers as well as project managers, they will be called on more to become brokers of information that will allow the public to use the transportation network in the most time- and cost-effective manner under adverse construction conditions.

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