01555205

Component

https://doi.org/10.3141/2521-11

Encroachment probability models such as the Roadside Safety Analysis Program (RSAP) have traditionally assumed that heavy vehicles and passenger vehicles share the same encroachment characteristics. This assumption was reviewed in developing bridge railing selection guidelines in NCHRP 22-12(03), where an examination of a specific highway and a national sample of data indicated that trucks encroached at a different rate than passenger vehicles. This paper describes the development of a new vehicle-type encroachment adjustment factor (EAF). The results confirmed previous findings, but this analysis controlled for traffic volumes, highway type, percentage of heavy vehicles [i.e., percentage of trucks (PT)], and segment length. The result was a more robust model that was valid over a wider range of average annual daily traffic and PTs. The large data set included 635,464 segments of data from the states of Ohio and Washington. The proposed EAF was recommended for inclusion in RSAPv3. Ideally, encroachment data would be collected for heavy vehicles to determine the frequency of heavy vehicles encroaching onto the roadside and the trajectories heavy vehicles took during encroachment, but this process proved to be financially challenging. The study used crash data to carry out a comprehensive analysis of traffic volume, heavy vehicle mix, highway type, and segment length. A vehicle-type EAF was developed for divided and undivided roadways. The results provided some indication of how best to incorporate heavy vehicles in the encroachment probability model used in RSAP.

01596466

15-1107

English

pp 103–110

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369619

Print

References (8) ; Tables (9)

Adjustment factors; Annual average daily traffic; Crash data; Heavy vehicles; Highway design; Highway safety; Traffic volume; Vehicle mix

Encroachment

Ohio; Washington (State)

Design; Highways; Safety and Human Factors; Vehicles and Equipment

TRIS, TRB, ATRI

Dec 30 2014 12:27PM

• Combined Crash Frequency–Crash Severity Evaluation of Geometric Design Decisions: Entrance–Exit Ramp Spacing and Auxiliary Lane Presence
• Continuous Speed Profiles to Investigate Drivers’ Behavior on Two-Lane Rural Highways
• Controlling Crest Vertical Curvature Rates Based on Variable Grade Stopping Sight Distance Calculation
• Design and Full-Scale Testing of Low-Cost Texas Department of Transportation Type T631 Bridge Rail for MASH Test Level 2 and 3 Applications
• Design Gap Acceptance for Right-Turning Vehicles Based on Vehicle Acceleration Capabilities
• Development of Socketed Foundations for Cable Guardrail Posts
• Heuristic Approach to Identifying Horizontal Curves and Their Parameters Given Lidar Point Cloud Data
• Innovations in Utility Conflict Management: Lessons Learned from Pilot Implementation of Utility Conflict Matrix Tools
• Installation Enhancements to Common Inlet Protection Practices Using Large-Scale Testing Techniques
• Minimum Effective Length for the Midwest Guardrail System
• Proposed Horizontal Curve and Vertical Grade Encroachment Adjustment Factors
• Quantitative Method for Assessing the Level of Deterioration of Round Wood Guardrail Posts
• Reduction in Fatal Longitudinal Barrier Crash Rate Due to Electronic Stability Control
• Reimagining the Right-of-Way: Designing Streets as Environmental and Economic Assets for Active Living and Healthy Environments
• Safety Effectiveness of Variable Speed Limit System in Adverse Weather Conditions on Challenging Roadway Geometry
• Streamlining of Bridge Piers as Scour Countermeasures: Effects of Curvature of Vertical Profiles (with Discussion and Closure)
• Streamlining of Bridge Piers as Scour Countermeasures: Optimization of Cross Sections (with Discussion and Closure)
• Use of Risk Analysis to Minimize Adverse Consequences in Nonstandard Designs