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As the overall fleet of Connected and Automated Vehicles (CAV) continues to grow across our Nation’s roadways, transportation professionals will be looking for new opportunities to build upon the successes of these vehicle technologies to improve overall roadway safety. Some estimates predict that as connected and automated vehicle technology merge (right now they are mostly independent) and become more prevalent within the vehicle fleet, traffic crashes will be reduced by as much as 47 percent for 25 percent CAV fleet penetration and as much as 80 percent when CAV fleet penetration reaches 50 percent (Carlson, 2020). However, these benefits may not be distributed equally by geography, functional class, or road user type.
Even if these potential safety benefits are only partly realized, they introduce a research need to consider how the integration of CAVs may change today’s state of practice regarding the implementation and evaluation of FHFWA’s proven safety countermeasures (PSC).
Research Objective
The objective of this research is to review current countermeasures for potential safety performance effectiveness as the vehicle fleet agencies transition to an increased number of CAV environment equipped vehicles. This evaluation included SAE J3016 Automation Levels L1-3 and a select list of PSCs. For each PSC the researchers assessed if:
- They are expected to maintain its safety effectiveness and no modifications would be needed.
- Their effectiveness would be enhanced with modifications (e.g., V2V or V2I connectivity, smart features, etc.).
- They would remain effective, but at some point in the future would be no longer needed (at Levels 4 and 5) due to technological advancements and CAV saturation.
- They would be less effective due to redundant CV and AV benefits.
- They would no longer be effective for safety, but other notable benefits would remain.
The following list of PSCs that was included in this project:
- Roadside Design Improvements at Curves
- Reduced Left-turn Conflict Intersections
- Systemic Applications at stop-controlled intersections
- Leading pedestrian interval
- Local road safety plan
- USLIMITS2
- Enhanced Delineation and Friction of Horizontal Curves
- Longitudinal Rumble Strips and Stripes on Two-Lane Roads
- Median Barrier
- Safety Edge
- Backplates with Retroreflective Borders
- Corridor Access Management
- Dedicated LT and RT lanes
- Roundabouts
- Yellow Change intervals
- Medians and Ped. Crossing Islands
- Pedestrian Hybrid Beacon
- Road Diets
- Walkways
- Road Safety Audit
Reference
Carlson, P. (2020). Impacts of Automated Vehicle on Highway Infrastructure. McLean, VA: FHWA.