A new study gathered data about convertible roadways and lanes which may
provide transportation officials with alternatives to mitigate traffic congestion. Baton Rouge engineers, Laurence Lambert of ABMB Engineers, Inc. and Brian Wolshon of Louisiana State University, recently co-authored a Convertible Roadways & Lanes Synthesis 340 for the National Cooperative Highway Research Program (NCHRP). This extensive study of convertible roadways and lanes established a central collection of data on this traffic movement strategy and created a national review of current methods utilized around the country.
Convertible roadways and lanes refer to roadway facilities that modify the existing geometry to temporarily increase capacity for high congestion situations. In some cities like Washington, DC, major highway systems are converted to flow traffic in one direction during peak hours, special events, or emergency situations. For example, a roadway consisting of six lanes (three in both directions) can be converted to have only two lanes operational in one direction while the other four lanes move in the opposing direction to boost capacity for a short duration. Another possible application familiar to southern and eastern residents of the United States is hurricane evacuation.
Convertible roadways and lanes can be a cost effective alternative to manage highly congested areas. As stated in this synthesis, “Convertible roadways encompass a variety of techniques that afford an agency an added measure of flexibility in how and when it responds to the needs for more on-street parking, additional intersection turning capability, and short-term corridor capacity.”
Lambert and Wolshon sent out over 150 surveys and contacted numerous transportation-related agencies across the country. Forty-nine responding agencies contributed to the study to help identify current applications for the concept and provide information about their effectiveness. The surveys identified the different agencies, how they were using convertible roadways, and the causes for use of the concept. Detailed information was gathered about how the lanes were converted and how drivers were informed of the change on the roadway. Depending on the budget of the community, or other agency, signage was provided which ranged from regular signage to complex overhead lighting control systems.
Lambert says, “This is a synthesis of highway practice. It will be used to supplement current nationally accepted transportation resource publications.” The past data on convertible roadways and lanes has been somewhat limited and not fully utilized by engineers nationally. “We’re hoping this study will assist other engineers in planning for this type design in the future.” According to the text of the study, “This synthesis was undertaken to address the need to increase the level of understanding of reversible roadways and to improve the knowledge of their characteristics and operational requirements, costs, and benefits so that reversible operations can be more effectively implemented in the future.”
The full text of the Synthesis for Convertible Roadways and Lanes can be accessed at http://trb.org/news/blurb_detail.asp?id=4660 for additional information.
Source: Transportation Research Board’s National Cooperative Highway Research Program (NCHRP)