01123205

Component

https://doi.org/10.3141/2103-08

http://scholar.google.com...orey&publication_year=2009

Increasingly, road authorities are collecting a variety of data sets related to their networks, including horizontal and vertical alignment, cross section, traffic volumes, crashes, and the location of features such as intersections and passing lanes. These data may be a mixture of point locations, fixed length records, and variable length records. A critical question concerning computational ease and practical usefulness is how best to aggregate or section the available data into appropriate road segments for operational and safety analyses. This issue is becoming more pertinent with the development of tools such as the Interactive Highway Safety Design Model (IHSDM) and the "Highway Safety Manual," which require a logical partition of roads based on many different attributes. The guidance on how to do this, however, is rather scant. Analysis of traffic exposure versus crash risk is also affected by the use of fixed or variable length segments. Research is nearing completion in New Zealand to combine road feature, geometry, and crash data on the national rural state highway network. The resulting database will enable better analysis of crash patterns against different types of road elements and will be used to calibrate IHSDM for New Zealand use. This paper outlines the investigation done to determine a rational method for aggregating the available data into logical road segments. The resulting method uses horizontal alignment, significant cross-section changes, and changes in speed limit. It also attempts to minimize the number of very short segments. The resulting data set contains approximately 83,400 segments generated from 20,900 lane km (13,000 lane mi) of highway.

01138796

09-0178

English

pp 61-68

2009

Transportation Research Record: Journal of the Transportation Research Board

9780309126182

Print

Figures (3) ; References (21) ; Tables (1)

Crash analysis; Crash data; Rural highways; Speed limits

Data aggregation

Highway Safety Manual; Interactive Highway Safety Design Model

Data segmentation; Horizontal alignment

New Zealand

Highways; Safety and Human Factors; I80: Accident Studies

TRIS, TRB, ATRI

Jan 30 2009 4:25PM

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• Analyzing Different Parameterizations of the Varying Dispersion Parameter as a Function of Segment Length
• Calibration of the Highway Safety Manual's Accident Prediction Model for Italian Secondary Road Network
• Comparison of Simulated Freeway Safety Performance with Observed Crashes
• Developing Accident Modification Functions: Exploratory Study
• Elementary Units of Exposure
• Empirical Evaluation of Alternative Approaches in Identifying Crash Hot Spots: Naive Ranking, Empirical Bayes, and Full Bayes Methods
• Incorporating Traffic Operation Measures in Safety Analysis at Signalized Intersections
• Safety Effectiveness of Lane and Shoulder Width Combinations on Rural, Two-Lane, Undivided Roads
• Safety Evaluation of Curve Delineation Improvements: Empirical Bayes Observational Before-and-After Study
• Speed and Safety
• Traffic Microsimulation Modeling to Study a Traffic Signal Incident Reduction Function