New geometric design consistency model based on operating speed profiles for road safety evaluation

Area of Science:

• Transportation Engineering
• Road Safety Analysis
• Traffic Engineering

Background:

• Reducing road fatalities is a critical ongoing effort.
• Existing methods for evaluating road safety may lack accuracy.
• Accurate assessment of road geometric design consistency is needed.

Purpose of the Study:

• To present a novel methodology for evaluating road safety in two-lane rural highways.
• To establish road geometric design consistency as a surrogate measure for safety.
• To develop a more accurate consistency model using continuous operating speed profiles.

Main Methods:

• Utilized an innovative GPS-data collection method for continuous operating speed profiles.
• Collected data from 33 Spanish two-lane rural road segments.
• Developed consistency models considering global and local operating speed, speed decelerations, and speeds over posted limits.

Main Results:

• The new methodology enables observation of actual driver behavior for more accurate speed models.
• The final consistency model incorporates global speed dispersion and local speed variations.
• Crash frequency data was used to link geometric design consistency to estimated crash numbers.

Conclusions:

• The developed consistency evaluation method is an innovative tool for road safety assessment.
• This method provides a reliable surrogate measure for estimating the safety of road segments.
• The findings can assist in designing and redesigning safer rural highways.