Eric R. Green

Crash Rates At Intersections

The objectives of this study were to develop a database of intersections, match traffic crashes to these intersections, calculate crash rates for various types of intersections, and identify intersections with the highest crash rates. A procedure was used to: a) identify intersections, b) assign crashes to these intersections, c) determine entering traffic volume, d) calculate a crash rate for each intersection, and e) calculate a critical rate factor (CRF) for each intersection. About 7,000 intersections were identified with almost 19,000 crashes related to these intersections for the three-year period of 2000 through 2002. The analysis identified 428 intersections that had a CRF of one or more while only 36 intersections had a CRF above two. As would be expected, the crash rates are higher in urban than in rural areas. In both rural and urban areas, the rate was highest for four-lane undivided highways and lowest for four-lane divided highways. An Excel spreadsheet containing a list of all intersections of two or more state-maintained roadways was developed. The spreadsheet also contains crash and volume data for each intersection. The intersections with the highest CRFs can be identified. This list can be divided by highway district with the objective of investigating the intersections with the highest CRFs and determining if improvements should be implemented.

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 Work Zone Safety Operations and Issues

The objectives of this research included the following: 1) evaluation of measures and procedures that will alter or control the speed of motorists in work zones, 2) investigate the feasibility of using automated equipment to replace flaggers in work zones, 3) develop policy and guidelines for use of elevated platforms near traffic, and 4) evaluate the safety issues associated with mobile and short-term work activities. In an attempt to determine the effectiveness of various speed control measures in work zones, speed data were collected for several strategies including signs, radar displays, and police enforcement. It was determined that the largest reduction in speed can be achieved with the presence of police enforcement at the work site. The use of automated flagger devices were investigated, and it was determined that these devices have potential for application in long-term lane closures at work zone locations such as bridge deck repairs. Flashing STOP/SLOW paddles were purchased and provided to maintenance personnel for evaluation. The paddles were used by employees with mixed results in terms of their practicality and durability. Guidelines for use of aerial lifts/elevated platforms were developed, in conjunction with a typical application drawing for aerial work within an intersection. Application of the guidelines and drawing were reviewed and discussed with representatives of the Kentucky Transportation Cabinet, with one area of focus being work over an open lane of traffic. A handbook was developed to provide guidelines for traffic control in short duration and mobile work zones, with additional examples provided for short-term maintenance on two-lane and multi-lane roads.

Evaluation of the Accuracy of GPS as a Method of Locating Traffic Collisions

The objectives of this study were to determine the accuracy of Global Positioning System (GPS) units as a traffic crash location tool, evaluate the accuracy of the location data obtained using the GPS units, and determine the largest sources of any errors found. The analysis showed that the currently used GPS unit is capable of obtaining accurate latitude and longitude data at a crash site that would allow the site to be properly located. However, substantial differences were found between the location of some crashes as identified with the GPS and milepoint (CRMP) data. Of a sample of 100 random crashes, 55% were found to have an accurate GPS reading and 58% were found to have an accurate CRMP location. There was a large range in the difference between the GPS and CRMP data by county and police agency. This shows both the accuracy that can be obtained with proper training and use as well as the lack of proper training and/or use of the GPS units at some jurisdictions. The source of errors found for the GPS data was related to the operator rather than the equipment or environment. The actions necessary to significantly improve the accuracy of the GPS data are manageable and relate to training, proper use of the GPS unit, care when placing the GPS data onto the crash report, and a minor modification to the crash report. The source of errors related to the CRMP data primarily dealt with improper interpretation of the milepoint log, inaccurate use of the available mileposts and lack of knowledge of current data available. A few edits of the crash data could be used which would significantly improve the accuracy of both the GPS and CRMP data. Recommendations were made to improve the accuracy of both GPS and CRMP data. These included additions to the GPS procedure pamphlet, a minor modification to the crash report, additional training in the use of the GPS unit, providing up-to-date milepoint logbooks, and using an edit which checks the accuracy of the GPS and CRMP data.

Evaluation of the Use of Snowplowable Raised Pavement Markers

The objective of this study was to evaluate the effectiveness and durability of snowplowable raised pavement markers (RPM) installed on the RPM system in Kentucky. The durability evaluation dealt with the marker housing. The data show that continued use of the currently approved snowplowable RPM can be justified if the castings are properly installed on new pavements with a commitment that the pavement will be maintained. An evaluation of centerline rumble strips installations showed that they should be considered on rural, two-lane roads with 12-foot lane widths (having new pavements) and paved shoulders.

Use of edge line markings on rural two-lane highways.

The objective of this study was to review roadway characteristics and crash data in Kentucky and determine if revisions should be made to current guidelines for the use of edge lines. Recommendations were made concerning the use of edge lines, centerlines, and paved shoulders on rural, two-lane roadways with varying pavement widths.

EVALUATION OF HIGH TRAFFIC CRASH CORRIDORS

The objectives of this study were to: a) determine a procedure to use to identify corridors in each highway district for which a detailed analysis of crash data should be conducted, b) develop a procedure to use to analyze the crash data and recommend countermeasures, and c) conduct a case study analysis for one selected corridor. A method was developed to select high crash corridors, by highway district. The procedure involved obtaining a list of routes in each district which traveled through more than one county, determining various attributes for each route, calculating a relative value for each attribute for each route, and developing a ranking method to select a route for each district. After a specific corridor is selected in a highway district, the crashes should be analyzed based on both a corridor basis and a review of high crash locations.

Analysis of Traffic Crash Data in Kentucky (2004-2008)

This report documents an analysis of traffic crash data in Kentucky for the years of 2004 through 2008. A primary objective of this study was to determine average crash statistics for Kentucky highways. Average and critical numbers and rates of crashes 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 crashes. The other primary objective of this study was to provide data that can be used in the preparation of the problem identification portion of Kentuckys Annual Highway Safety Plan. County and city crash statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented. These general areas include: alcohol involvement, occupant protection, speed, teenage drivers, pedestrians, bicycles, motorcycles, trucks, and vehicle defects. Other areas included in the analysis for which specific recommendations were not made include drug involvement, school bus crashes, and train crashes. The crash data are now contained in the Collision Report Analysis for Safer Highways (CRASH) data base. This data base is updated daily so the number of crashes in a given calendar year will continue to change for a substantial time after the end of that year.

Analysis of Traffic Crash Data in Kentucky (2002 - 2006)

This report documents an analysis of traffic crash data in Kentucky for the years of 2002 through 2006. A primary objective of this study was to determine average crash statistics for Kentucky highways. Average and critical numbers and rates of crashes were calculated for various types of highways in rural and urban areas. These data can be used in Kentucky’s procedure to identify locations that have abnormal rates or numbers of crashes. The other primary objective of this study was to provide data that can be used in the preparation of the problem identification portion of Kentucky’s Annual Highway Safety Plan. County and city crash statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented. These general areas include; alcohol involvement, occupant protection, speed, teenage drivers, pedestrians, bicycles, motorcycles, trucks, and vehicle defects. Other areas included in the analysis for which specific recommendations were not made include drug involvement, school bus crashes, and train crashes. The crash data are now contained in the Collision Report Analysis for Safer Highways (CRASH) data base. This data base is updated daily so the number of crashes in a given calendar year will continue to change for a substantial time after the end of that year.

Analysis of Traffic Crash Data in Kentucky (2001-2005)

This report documents an analysis of traffic crash data in Kentucky for the years of 2001 through 2005. A primary objective of this study was to determine average crash statistics for Kentucky highways. Average and critical numbers and rates of crashes 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 crashes. The other primary objective of this study was to provide data that can be used in the preparation of the problem identification portion of Kentuckys Annual Highway Safety Plan. County and city crash statistics were analyzed. A summary of results and recommendations in several problem identification areas is presented. These general areas include: alcohol involvement, occupant protection, speed, teenage drivers, pedestrians, bicycles, motorcycles, trucks, and vehicle defects. Other areas included in the analysis for which specific recommendations were not made include drug involvement, school bus crashes, and train crashes. The crash data are now contained in the Collision Report Analysis for Safer Highways (CRASH) data base. This data base is updated daily so the number of crashes in a given calendar year will continue to change for a substantial time after the end of that year.