摘要: |
Many urban freeways in Texas experience congested traffic conditions during peak periods. Freeway system expansion is very expensive and time-consuming. Consequently, alternatives other than construction of new facilities are desired. The Texas Department of Transportation has been implementing comparatively inexpensive methods to improve existing freeways such as grade-separated (i.e., braided) ramps and modified ramp configurations via X-ramp interchanges and ramp reversals. Ramp reversal, replacement of an entrance ramp with an exit ramp or vice versa, is an improvement strategy occasionally recommended by outside constituencies. The basis for this research was driven by Texas Department of Transportation (TxDOT) engineers need to have an updated methodology and evaluation results from previously implemented ramp reversal projects to assist in future decision-making. This research project investigated the benefits and impacts of X-ramp and ramp reversal projects. Impacts that were evaluated include operational, safety, and basic economic benefits. Case study evaluations of 15 projects implemented throughout the state were performed and generally showed that ramp modification projects are a worthwhile effort. The final product of this research was the development of guidelines for TxDOT staff to assist in the evaluation and implementation of ramp modification projects. The framework for the guidelines was based on the three themes for the Texas access management program: (1) improve safety and mobility, (2) provide reasonable access to developments, and (3) promote local government partnerships. Based on this framework, the 21 guidelines for successful implementation were further divided into five categories: educational, encouragement, engineering, enforcement, and evaluation. / NOTE: Technical rept. (Sept. 2005 - Mar. 2006). / Supplementary Notes: Prepared in cooperation with Texas Univ. at Arlington. Sponsored by Texas Dept. of Transportation, Austin. Research and Technology Implementation Office. and Federal Highway Administration, Austin, TX. Texas Div. / Availability Note: Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA. |