00756132

Component

https://doi.org/10.3141/1635-02

http://scholar.google.com...ncil&publication_year=1998

A vehicle entering or departing a horizontal curve must safely undergo a change in steering angle and a resulting change in side friction forces. The safety-related effects of two alternative designs were evaluated for the "transition" sections of pavement where the curve and tangent meet - a spiral transition, where the tangent and curve are linked by an ever-tightening spiral curve, and a nonspiral transition where the tangent directly abuts the horizontal curve. Using crash and roadway inventory data from over 15,000 transition sections (curve ends) in the state of Washington, contingency table analyses and linear logistic modeling were conducted to explore differences in the probability of one or more crashes on the two types of transitions within each of three types of terrain - level, rolling, and mountainous. At level terrain sites, spiral presence is related to a decrease in crash probability on curve ends with degree of curve greater than approximately 3 degrees. For rolling terrain, a decrease was predicted for all sites on minor arterials and major collectors, and for principal arterials sites with average daily traffic greater than 3,700 vehicles per day. In contrast, in mountainous terrain, an increase in crash probability due to the spiral was predicted for all sites except those with both wider roadway widths and wider shoulders. The models for the mountainous terrain sites did not fit the data as well, indicating the presence of other unmeasured confounding variables.

This paper appears in Transportation Research Record No. 1635, Safety Analysis Related to Highway Design, Crash Costs, and Traffic Records Systems; Methodologies for Evaluating Safety Improvements.

English

p. 10-17

1998

Transportation Research Record

0309065070

Figures (1) ; References (9) ; Tables (2)

Benefits; Crash data; Curves (Geometry); Highway safety; Mathematical models; Probability; Rural highways; Spirals; Transition curves; Two lane highways

Horizontal curvature

Data and Information Technology; Design; Highways; Safety and Human Factors; I82: Accidents and Transport Infrastructure

TRIS, TRB, ATRI

Nov 9 1998 12:00AM

• ACCIDENT MODELS FOR TWO-LANE RURAL SEGMENTS AND INTERSECTIONS
• ALLOCATING THE COSTS OF MOTOR VEHICLE CRASHES BETWEEN VEHICLE TYPES
• APPLYING THE ORDERED PROBIT MODEL TO INJURY SEVERITY IN TRUCK-PASSENGER CAR REAR-END COLLISIONS
• CONFLICT ANALYSIS FOR DOUBLE LEFT-TURN LANES WITH PROTECTED-PLUS-PERMITTED SIGNAL PHASES
• CONSIDERATION OF BOLLARD TREATMENT AT EXIT GORE AREAS
• DEVELOPMENT OF EXPECTED CONFLICT VALUE TABLES FOR UNSIGNALIZED THREE-LEGGED INTERSECTIONS
• DEVELOPMENT OF SAFETY-BASED LEVEL-OF-SERVICE PARAMETERS FOR TWO-WAY STOP-CONTROLLED INTERSECTIONS
• DISAGGREGATE SAFETY PERFORMANCE MODELS FOR SIGNALIZED INTERSECTIONS ON ONTARIO PROVINCIAL ROADS
• EFFECT OF ENVIRONMENTAL FACTORS ON DRIVER SPEED: A CASE STUDY
• EFFECTS OF A TOWAWAY REPORTING THRESHOLD ON CRASH ANALYSIS RESULTS
• EVALUATING MEDIAN CROSSOVER LIKELIHOODS WITH CLUSTERED ACCIDENT COUNTS: AN EMPIRICAL INQUIRY USING THE RANDOM EFFECTS NEGATIVE BINOMIAL MODEL
• EXPLORATORY MULTIVARIABLE ANALYSES OF CALIFORNIA DRIVER RECORD ACCIDENT RATES
• INVESTIGATION OF NATIONAL HIGHWAY SYSTEM ROADWAYS IN THE HIGHWAY SAFETY INFORMATION SYSTEM STATES
• INVESTIGATION OF THE EFFECTIVENESS OF BOULEVARD ROADWAYS
• POLICE REPORTING OF PEDESTRIANS AND BICYCLISTS TREATED IN HOSPITAL EMERGENCY ROOMS
• PREDICTING VEHICLE OCCUPANCIES FROM ACCIDENT DATA: AN ACCIDENT SEVERITY APPROACH
• PREDICTION MODELS FOR TRUCK ACCIDENTS AT FREEWAY RAMPS IN WASHINGTON STATE USING REGRESSION AND ARTIFICIAL INTELLIGENCE TECHNIQUES
• SAFETY EVALUATION OF ALTERNATIVE SIGNAL HEAD DESIGN
• SEASONAL VARIATIONS IN THE AGE-RELATED COLLISION RISK OF ONTARIO DRIVERS
• SPOT SPEED ANALYSIS ON URBAN ROADS IN RIYADH
• TWO PROBLEMS OF AVERAGING ARISING IN THE ESTIMATION OF THE RELATIONSHIP BETWEEN ACCIDENTS AND TRAFFIC FLOW