•Germany’s Autobahns: Speed Harmonization via VSL
Signing
•Implementation
highlights:
•200 km of roadway covered
•Loops for traffic flow
conditions, weather (fog) detectors
•VISSIM microscopic traffic
simulation to tune VSL algorithms
•Advisory (non-enforced)
speed limits
•Findings:
•20-30% crash rate reduction
in speed harmonization zones
Netherland’s A2 and A16: Speed Harmonization via VSL
Signing
Implementation
highlights:
•Loop
detectors every 500 m; automatic incident
detection
•Mandatory
speed limits enforced by photo radar
•System
revises posted speed limit every minute
•Objective
to keep the posted and average actual speeds aligned
Findings:
•Increased
traffic flow homogeneity (reduced speed variations)
•Less
severe shockwaves and reduced average headways
•High
compliance rates due to enforcement and public awareness of system
•