The AASHTO Policy on Geometric Design of Highways and Streets (Green Book) provides design criteria for permanent highway and street facilities. It does not provide guidance for design of high-speed highway construction work zones, including temporary geometrics (e.g., ramps, crossovers, traffic lane shifts, and bypasses). Also, the Manual on Uniform Traffic Control Devices (MUTCD) includes a chapter on temporary traffic controls, but there is no direct link with the Green Book.
Work zones require drivers to increase their attention in order to discern situations requiring special care. These special situations include the temporary geometrics that occur on the high-speed facilities that carry much of the nation's traffic. The consequences of errors made at high rates of speed are generally severe. U.S. DOT data show that most fatal work zone crashes for all vehicles and large trucks occurred on roads with speed limits of 55 miles per hour or greater.
Both the American Association of State Highway and Transportation Officials (AASHTO), through its Strategic Highway Safety Plan, and the Federal Highway Administration (FHWA) consider improvement of work zone safety and mobility a high priority. From 1995 to 1999, on average, 39,000 people were injured as a result of motor vehicle crashes in work zones. Recent data available for work zone crashes show an increase in fatalities from 872 in 1999 to 1,026 in 2000.
Designers have little guidance available to suggest how highway construction work zones should be designed. Better information and design guidelines are needed to assist designers in making decisions about the safest and most effective work zone design and traffic control treatments.
The objective of this project is to develop a methodology that assists designers in developing appropriate design and traffic control recommendations for safe and efficient movement of traffic through construction work zones on high-speed highways. For the purpose of this project, the definition of high speed shall be consistent with AASHTO guidelines. This project includes both urban and rural highways. A design decision-making methodology should be developed to provide a comprehensive, systematic review of the components (e.g., horizontal and vertical alignment, lane widths, reverse crowns/superelevations, drainage, and trucks) of design and traffic control plans for construction work zones.
Accomplishment of the project objective will require at least the following tasks.
TASKS (1:) Conduct a literature review of available information on construction work zone design and traffic control, including applicable information from non-work zone studies such as, but not limited to, design consistency and speed management. (2:) Review the ongoing FHWA research effort, "Work Zone Accident Exposure," and other relevant research on work zone crashes to identify problems that could be addressed through improved design and traffic control.
(3:) Conduct a survey of the states to collect guidance related to construction work zone design and traffic control. (4.) Submit an interim report summarizing the results of Tasks 1 through 3. The interim report shall identify the problems with design and traffic control treatments in construction work zones; identify topics requiring additional research; and propose an updated work plan for addressing such topics and developing the needed methodology. In updating the work plan, consideration should be given to elements such as, but not limited to, vehicle simulation; field-data collection; and cost-benefit, crash, and human factor analyses. The work plan should describe the advantages and disadvantages of each of the elements in the proposed work plan. The work plan shall include cost estimates for needed research on each element to allow the panel latitude in selecting one or more elements to be studied in this project. (5.) Meet with the NCHRP panel to review the Task 4 interim report, approximately 1 month after its submittal. Submit a revised interim report addressing the panel's review comments. (6.) Execute the approved work plan. (7.) Prepare a second interim report summarizing the results of Task 6, including the draft recommendations for the design-decision methodology. The contractor shall be prepared to demonstrate the applicability of the methodology in case-study examples. (8.) Meet with the NCHRP panel and up to 10 additional subject area experts to review the Task 7 interim report, approximately 1 month after its submittal. The review comments shall be addressed in the preliminary draft final report. (9.) Submit the final report documenting the entire research effort. The final report shall describe how the project was conducted and include an appendix with the design-decision methodology.
Status: The project is completed.
Product Availability: The final report, including a summary of the literature and survey, is available as NCHRP Web-Only Document 105. The set of guidelines has been published as NCHRP Report 581.
As part of the research associated with this activity, a work zone prediction model and user's guide was created to help estimate free-flow vehicle speeds through two types of construction work zones on four lane freeways--single lane closures and median crossovers.