Jodi Carson

The effect of ice warning signs on ice-accident frequencies and severities.

Signing of non-permanent road surface conditions, such as ice, is difficult because hazard formation, location, and duration are unpredictable. Subsequently, many state transportation departments have begun to question the sensibility of expending material and personnel resources to maintain ice warning signs when little proof exists of their effectiveness in improving highway safety. This research statistically studies the effectiveness of ice warning signs in reducing accident frequency and accident severity in Washington State. Our findings show that the presence of ice warning signs was not a significant factor in reducing ice-accident frequency or ice-accident severity. However, we were able to identify significant spatial, temporal, traffic, roadway and accident characteristics that influenced ice-accident frequency and severity. The identification of these characteristics will allow for better placement of ice warning signs and improvements in roadway and roadside design that can reduce the frequency and severity of ice-related accidents.

AN ALTERNATIVE ACCIDENT PREDICTION MODEL FOR HIGHWAY-RAIL INTERFACES

Safety levels at highway/rail interfaces continue to be of major concern despite an ever-increasing focus on improved design and appurtenance application practices. Despite the encouraging trend towards improved safety, accident frequencies remain high, many of which result in fatalities. More than half of these accidents occur at public crossings, where active warning devices (i.e. gates, lights, bells, etc.) are in place and functioning properly. This phenomenon speaks directly to the need to re-examine both safety evaluation (i.e. accident prediction) methods and design practices at highway-rail crossings. With respect to earlier developed accident prediction methods, the Peabody Dimmick Formula, the New Hampshire Index and the National Cooperative Highway Research Program (NCHRP) Hazard Index, all lack descriptive capabilities due to their limited number of explanatory variables. Further, each has unique limitations that are detailed in this paper. The US Department of Transportations (USDOT) Accident Prediction Formula, which is most widely, also has limitations related to the complexity of the three-stage formula and its decline in accident prediction model accuracy over time. This investigation resulted in the development of an alternate highway-rail crossing accident prediction model, using negative binomial regression that shows great promise. The benefit to be gained through the application of this alternate model is (1) a greatly simplified, one-step estimation process; (2) comparable supporting data requirements and (3) interpretation of both the magnitude and direction of the effect of the factors found to significantly influence highway-rail crossing accident frequencies.

ARE INCIDENT MANAGEMENT PROGRAMS EFFECTIVE? FINDINGS FROM WASHINGTON STATE

The development of an incident response team (IRT) program has been touted to improve incident response and clearance times, as well as to improve interdisciplinary cooperation. To determine the effectiveness of its IRT program, the Washington State Department of Transportation (WSDOT) commissioned a comprehensive study that considered both quantified and perceived benefits. The average duration of incidents to which the IRTs responded was reduced by 20.6 min from 1994 to 1995. The ability to statistically attribute this reduction in incident duration to the IRT was limited because only 2 years of data were available (i.e., reduction may be attributable to temporal variations in incident characteristics). Nonetheless, the implications of this reduction can be quantified. This reduction results in a monetary savings of

FACTORS FOR RATING CONDITION OF CULVERTS FOR REPAIR OR REPLACEMENT NEEDS

20,600 to

Preservation of Infrastructure by Using Weigh-in-Motion Coordinated Weight Enforcement

61,800 per incident and an annual savings of

MONTANA REST AREA PLAN

3.09 million to

AN EVALUATION OF MONTANA'S STATE TRUCK ACTIVITIES REPORTING SYSTEM

9.27 million in King County. Comparing these monetary benefits to the IRT program, costs in the Northwest Region result in a benefit-to-cost ratio of 4.3:1 to 12.9:1. Given these values, even minor reductions in incident duration attributable to IRTs can justify the program. Public support for WSDOT’s incident response team program was high, with 62 percent of the respondents thinking it is a good idea. IRT program support from other response personnel was also high. WSDOT’s IRT was viewed as an important service for improving scene accessibility and improving the safety of both the motoring public and the incident responders. Despite the positive feedback, inconsistency in operation among individual IRT members makes it difficult to draw conclusions as to the effectiveness of different operating styles, for other response personnel to work effectively with IRT members, and to build a positive consensus among the motoring public for continued program support.

INFRASTRUCTURE PRESERVATION USING WIM COORDINATED WEIGHT ENFORCEMENT

Many aspects of transportation infrastructure have benefited from the use of full-scale management systems to quantify condition and predict useful life estimates. Although culvert management models have been tested in the past, none has proven functional. In this study, a condition rating system for culvert repair or replacement was developed. Parameters that describe the condition of an existing culvert were tested for potential as predictors of overall culvert condition. These 33 parameters were recorded at 460 culverts distributed geographically throughout Montana. An ordered probit statistical model indicated that 9 of the initial 33 potential predictors were statistically significant. Measurements of these nine parameters can be used in the resulting model to classify a culvert into a 1-to-5 condition ranking, in which 5 is the best condition and 1 is the worst.

UTILIZING ROAD WEATHER INFORMATION SYSTEM (RWIS) DATA TO IMPROVE RESPONSES TO ADVERSE WEATHER CONDITIONS

The Montana Department of Transportation (DOT) has completed a pilot project in which data from a statewide network of weigh-in-motion (WIM) sensors were used to assist in scheduling weight-enforcement activities of patrol personnel. The purpose of the project was to determine if one of the division’s objectives—reducing infrastructure damage from overweight vehicles—could be better realized by using WIM data when dispatching officers. Data for the project were obtained from Montana’s state truck activities reporting system (STARS), which consists of WIM sites deployed around the state to collect information for a spectrum of Montana DOT activities. In this case, the STARS data were processed to determine the pavement damage caused by overweight vehicles each month during the baseline year. The trends identified from this analysis were used in the subsequent year to direct patrol efforts each month to the five sites that historically had experienced the greatest pavement damage from overweight vehicles. Officers were directed to the specific vehicle configurations historically responsible for the damage, as well as to their direction of travel and time of operation. During this year of WIM-directed enforcement, pavement damage from overweight vehicles decreased by 4.8 million equivalent single-axle load miles, and the percentage of vehicles operating over weight decreased by 20% across all STARS sites (both enforced and unenforced). While changes in loading patterns were observed during the enforcement activities (fewer overweight and more weight-compliant vehicles), the effectiveness of the focused enforcement in producing long-term changes in loading behaviors was uncertain.