The primary objective of the research was to identify and evaluate effective ways of improving traffic operations and safety on congested freeways. There was particular interest in finding condition-responsive traffic control solutions for the following problem areas: (1) end-of-queue warning, (2) work zones with lane closure, and (3) queue spillover at exit ramps. Available techniques considered by this research include combination of static and dynamic queue warning systems, dynamic merge control in advance of freeway lane closures, and various traffic control strategies, such as traffic diversion and ramp metering, to mitigate queue spillover at exit ramps. Three sets of evaluation studies were conducted: first, two queue warning systems deployed on IH 610 and US 59 in Houston, Texas, were evaluated based on field observations. Second, strategies to resolve a ramp spillover problem at an exit ramp in El Paso, Texas, were analyzed using traffic simulations. Third, the Dynamic Merge work zone traffic control concept was evaluated using traffic simulations, and recommendations were developed for its potential use for various work zone types with different lane closure configurations.

Research was performed to determine total costs (construction and road user costs) and safety impacts associated with traffic control through work zones on rural four-lane, divided highways using single lane closure (SLC) versus two-lane, two-way traffic operations (TLTWO). An informational guide for use in selecting cost-effective traffic control strategies for proposed construction projects was also prepared. Construction data were collected from 51 construction projects in 11 States, and traffic capacity delay studies were conducted at 25 projects in 10 States. Guidelines are presented in this report for selection of the best traffic control alternative between SLC and TLTWO. A simplified procedure to estimate road user costs for SLC and TLTWO traffic control strategies is also included. This guide is Volume II of a two-volume series. Volume I (FHWA-RD-89-209) is the final report.

Congestion continues to grow in America¿s urban areas. This report presents details on the 2004 trends, findings and what can be done to address the growing transportation problems. Trend data from 1982 to 2002 for 85 urban areas provides both a local view and a national perspective on the growth and extent of traffic congestion. The 2004 Report provides clear evidence that the time for improvements has arrived. Communicating the congestion levels and the need for improvements is a goal of this report. The decisions about which, and how much, improvement to fund will be made at the local level according to a variety of goals, but there are some broad conclusions that can be drawn from this database. Tables.

One of the ways a state department of transportation or other transportation agency can address work zone safety and other impacts is to develop and implement a Transportation Management Plan (TMP). The TRB National Cooperative Highway Research Program's NCHRP Research Report 945: Strategies for Work Zone Transportation Management Plans provides a practitioner-ready guidebook on how to select and implement strategies that improve safety and traffic operations in roadway construction work zones. Supplemental materials to the report include NCHRP Web-Only Document 276: Evaluating Strategies for Work ZoneTransportation Management Plans; fact sheets on ramp meter, reversible lane, and truck restrictions; and guidebook appendices.