Kenneth R. Agent

Development of Accident Reduction Factors

The objective of this project is to develop accident reduction factors associated with various types of highway safety improvements. These factors will be used in the cost-optimization procedure to rank safety improvements. The basis of the accident reduction factors developed in this study is a survey of states and a review of literature. The recommended reduction factors are presented in a table which lists the percent reduction in all accidents or specific types of accidents for given types of improvements.

Development of Procedures for Identifying High-Crash Locations and Prioritizing Safety Improvements

The objectives of this study were to review and analyze the current procedures for identifying high-crash locations and evaluating and prioritizing roadway safety improvements at high-crash locations, and to recommend improved methods. Several tasks were undertaken to accomplish these objectives, including the following: review of program guidelines and procedures used by other states to prioritize improvements at high-crash locations; review and documentation of Kentuckys current procedure; update of Kentuckys Crash Buildup Program software to be compatible with the 2000 crash report form; development of new software to assist in estimating the benefits and costs of potential projects for inclusion in the Hazard Elimination Program; and conversion of the dynamic programming software from mainframe to PC. Results from the study include improved methods for identifying high-frequency crash locations and prioritizing those locations after preliminary analyses indicated a need to consider improvements at a crash site. Software was developed to assist in producing a generalized estimate of the benefits of potential projects for inclusion in the Hazard Elimination Program. To use the software, the user must input the improvements to be made, the current level of crashes for the highway segment, and estimated project costs. Adjustments can also be made for key factors such as discount rate and projected traffic growth. Features include a menu of types of improvement projects and related reduction factors, and benefit-cost comparisons for each project. Revisions were recommended for updating and enhancing the Crash Buildup Program to achieve compatibility with the current crash data report form and for translating the dynamic programming module from a mainframe operation to a PC-based system. It appears that an increased level of functionality has been achieved as a result of the series of modifications and improvements.

EVALUATION OF CHANGE INTERVAL TREATMENTS FOR TRAFFIC SIGNALS AT HIGH-SPEED INTERSECTIONS

A large number of traffic accidents at signalized intersections on high-speed roadways occur during or just after the change interval. The green extension system (GES) has been used extensively in Kentucky as a method of alleviating the problem related to the dilemma zone. An alternate method of handling this problem involves warning drivers that the signal indication is about to change from green to red using advance warning flashers (AWF). The objectives of the study were: 1) to evaluate the alternative methods (GES or AWF) which can be used to lessen the problem associated with the dilemma zone which occurs at traffic signals, specifically on high-speed roadways and 2) to determine conditions where use of the AWF may be needed.

EVALUATION OF ADVANCED SURVEYING TECHNOLOGY FOR ACCIDENT INVESTIGATION

The objective was to evaluate the use of advanced technology for the investigation of traffic accidents. Substantial time and manpower are sometimes required to properly investigate serious vehicular crashes and document on-scene data. An alternative to the traditional coordinate method for on-scene data collection is the use of electronic total stations. This is a form of digital surveying equipment that can be used to obtain detailed measurements, with the option of plotting the stored data by computer. The study compared the use of advanced surveying technology with the traditional coordinate method. Detailed estimates of data collection activity were documented for a selected accident sample, and accident clearance times were documented for a much larger sample. The analysis indicated that the investigation of traffic accidents by using total-station surveys provides a substantial improvement over the traditional coordinate procedure. The number of measurements obtained at an accident scene increased by a factor of approximately 2 when the total-station equipment was used. The time to collect the data decreased by about 33%, and the man-hours decreased by about one-half. Computer plotting by the total-station procedure also resulted in a significant time savings. Decreased data collection time resulted in significant time and fuel savings to the driving public. Recommendations were made for continued use of the equipment and the purchase of more equipment when funds become available. In addition, policies for using the total-station equipment at all fatal and serious injury traffic accidents are recommended.

PERFORMANCE OF GUARDRAIL END TREATMENTS IN TRAFFIC ACCIDENTS

The objective of this study was to report the results of the continued monitoring of the performance of guardrail end treatments in traffic accidents. This report includes an analysis of accidents involving the breakaway-cable-terminal (BCT), Kentuckys version of the median BCT (MBCT), Kentuckys weakened turned down (Type 7), the Crash Cushion Attenuating Terminal (CAT), and the Breakmaster System. The report includes data for 349 accidents. This includes 232 accidents involving a BCT, 66 accidents involving a MBCT, 37 accidents involving the Type 7 turned-down end treatment, 12 accidents involving the CAT, and 2 accidents involving the Breakmaster. Considering all accidents, the BCT performed properly in 76% of the accidents. A more detailed analysis showed the importance of installing the BCT using the parabolic flare. Use of the BCT end treatment should be continued where geometrics permit. While the MBCT performed properly in 64% of all accidents, proper performance was 39% when only severe impacts were considered. Use of the MBCT should be eliminated or the MBCT modified due to the problems associated with impacts at shallow angles. Performance of the Type 7 weakened turned-down end treatment was judged to be proper in 84% of the accidents involving this type. Performance appears to justify expanded use. The rollover problem experienced with the original stiff turned-down design has been significantly reduced. Performence was judged to be proper in 9 of the 12 accidents involving the CAT. Considering the results of CAT impacts in Kentucky, along with those in other states, permits the conclusion to be drawn that the CAT could be classified as operational. The Breakmaster system may provide an alternative to the CAT; however, additional accident data are needed to evaluate the performance of this system.

Roadway Related Tort Liability and Risk Management

The training material has been prepared to address the tort liability problems faced by the Kentucky Transportation Cabinet and Kentucky local governments. The workbook defines the problem by reviewing the national picture of growing numbers of suits and escalating financial losses from suits against highway agencies. The workbook also sets out solutions, and reviews actions which can decrease the exposure of highway agencies to these suits. The risk management concept is emphasized throughout the workbook.

U-TURNS AT SIGNALIZED INTERSECTIONS

The objectives of the study were to examine the safety consequences from the installation of U-turns at signalized intersections in Kentucky and to develop a set of guidelines for using this alternative in the future. The literature review indicated that the use of U-turns is very effective in reducing delays as well as crash rates. The most efficient configuration is that of stop-controlled median U-turns. An analysis of the crash data shows that the U-turn design in the Kentucky locations did not result in a large number of crashes involving U-turning vehicles. Also, at the Somerset location where the design eliminated median crossovers between intersections, there was a decrease in total crashes. Potential factors that could affect the implementation of U-turns at intersections were examined. Using delay time as a measure of effectiveness, it was concluded that the presence of the U-turn enhances the operation of the corridor, most likely due to the more efficient processing of vehicles at the downstream intersection. The study recommends that U-turns should be considered for corridors with peak volumes greater than 1,500 vph or for cases where the expected total turn volume is greater than 20% of the total approach volume.

EVALUATION OF SHRP WORK ZONE SAFETY DEVICES

The objective of this study was to use and evaluate various Strategic Highway Research Program (SHRP) work zone devices. Experience with the use of these devices was obtained through trial use by the Kentucky Transportation Cabinet and various city, county, and private agencies. The devices included in the study were: Flashing Stop/Slow Paddle; All-Terrain Sign and Stand; Portable Rumble Strip; Opposing Traffic Lane Divider; and Intrusion Alarm. The experience with the flashing stop/slow paddles was very positive indicating the potential for expanded use in the future. Six different models of flashing paddles were evaluated with some having better results than others. While the all-terrain stand and sign was effective, its future use is limited by both its cost and difficulty to use. The use of the portable rumble strip will be limited by its difficulty to use, related to both its weight and inability to stay in place on high speed roads. The opposing traffic lane divider shows potential for use as a supplement to the standard tubular marker but must be used at locations where it is not routinely hit by traffic. Lane dividers from three manufacturers were tested with varying degrees of success. The intrusion alarm has the potential for use on major projects with its cost limiting its use. The continuing modifications made to the intrusion alarms during the study period made it difficult to obtain a complete evaluation or recommendation for a specific unit. Intrusion alarms from five manufacturers were evaluated.

PROPOSAL FOR DEVELOPMENT OF A RESOURCE AND COMMODITY HIGHWAY SYSTEM.

In 1986, the Kentucky General Assembly established the Extended Weight Coal and Coal By-Products Haul Road System. The system includes approximately 3,200 miles of the most significant coal-haul roads in the state and permits coal trucks to carry much larger payloads than trucks with other commodities. In many ways, the extended-weight system has been very successful. Coal-transportation productivity has been substantially increased, and Kentucky coal continues to remain competitive in the marketplace. The study, conducted by the Kentucky Transportation Center, concluded that development of a statewide trucking network, herein named the Resource and Commodity Highway System, was both feasibile and desirable.

Analysis of Traffic Accident Data in Kentucky (1986-1990)

This report includes an analysis of traffic accident data in Kentucky for the years of 1986-1990. A primary objective of this study was to determine average accident statistics for Kentucky highways. Average and critical number and rates of accidents were calculated for various types of highways in rural and urban areas. These data can be used in Kentuckys procedure to identify locations that have abnormal rates or numbers of accidents. Another objective of this study was to provide data which can be used in the preparation of the problem identification portion of Kentuckys Annual Highway Safety Plan. County and city accident statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented. These general areas include alcohol, occupant protection, speed, pedestrians, bicycles, motorcycles, and vehicle defects. Other areas included in the analysis are drugs, school bus accidents, and truck accidents.