Anthony P Voigt

Dual-Advisory Speed Signing on Freeway-to-Freeway Connectors in Texas

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.

Accelerating Major Freeway Reconstruction Projects: The Houston Experience

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.

Applications of Illuminated, Active, In-Pavement Marker Systems

Illuminated, active, in-pavement marker systems (IPMs) can provide a greater level of information to road users than conventional pavement marker systems. Traditionally, IPMs have been used for airport runways and taxiways, and pedestrian crosswalks. More recently, IPMs have been applied in numerous traffic guidance applications. This report documents (1) the state of IPM technology, (2) notable experiences with historical IPM applications, (3) detailed experiences with more recent IPM applications, and (4) IPM research needs. The report will be of particular interest to the traffic and safety engineering community. Information for this report was obtained through a review of published literature, a formal survey of transportation practitioners, an informal survey of IPM vendors and users, and follow-up interviews.

Economic Assessment of Access Management Projects in the Houston, Texas, Region

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.

Possible Expectancy Violations on Frontage and Conventional Roads at Interchanges: Solutions for Lane Assignment Traffic Control Signs

The intersection and mandatory movement lane control signs placed on intersection approaches are critical to safe and efficient intersection operations. Ramp, frontage road, and cross-street approaches to interchanges often widen at intersections to accommodate additional through or turn lanes. Currently, there is inconsistency in conveying to drivers how they should align themselves upstream of a diamond intersection to maneuver for their desired turning movement as the intersection widens. These inconsistencies can result in drivers making an incorrect lane selection that may result in late lane changes or illegal turns. This paper focuses on the expectancy violations that were discovered by a driver survey portion of a larger project that included practitioner surveys and a field evaluation of sign alternatives. A computer-based driver survey sampled 204 Texas drivers in four cities. The questions reported in this paper focused on driver expectations of lane movement and assignment on frontage road approaches to cross streets on freeway on- and off-ramps. Findings that showed that drivers are often incorrect in their assumptions about lane assignment when approaching intersections indicate a greater need for advanced lane control signs. A new sign design, adopted from Australian practice, that graphically shows lane additions and drops was the most effective for cases in which the downstream geometry varied from the drivers expectations.