Safety Elements of Modern Roundabout ProWalk/ProBike September 8, 2004 Michael M. Moule, PE, PTOE
Weaver UNC-Asheville Main Entrance
Crash Statistics - The Netherlands Source: FHWA Roundabout Guide Crash reductions by mode at intersections converted to roundabouts
Intersection Size Affects Safety
Motor Vehicle Conflict Points 4-way intersection Roundabout Source: FHWA Roundabout Guide
Motor Vehicle Conflict Points 4-way intersection 4-way IntersectionRoundabout 32 total conflicts8 total conflicts Source: FHWA Roundabout Guide
Motor Vehicle Conflict Points 4-way intersection 4-way IntersectionRoundabout 32 total conflicts8 total conflicts 8 merging conflicts4 merging conflicts 8 diverging conflicts4 diverging conflicts Source: FHWA Roundabout Guide
Motor Vehicle Conflict Points 4-way intersection 4-way IntersectionRoundabout 32 total conflicts8 total conflicts 8 merging conflicts4 merging conflicts 8 diverging conflicts4 diverging conflicts 16 crossing conflicts0 crossing conflicts Source: FHWA Roundabout Guide
Motor Vehicle Conflict Points 4-way intersection 4-way IntersectionRoundabout 32 total conflicts8 total conflicts 8 merging conflicts4 merging conflicts 8 diverging conflicts4 diverging conflicts 16 crossing conflicts0 crossing conflicts High Speed, High Angle Crashes Low speed, Low angle crashes Source: FHWA Roundabout Guide
Motor Vehicle Crash Statistics Source: FHWA Roundabout Guide
Motor Vehicle Crash Statistics Source: FHWA Roundabout Guide
Pedestrian Conflict Points Source: FHWA Roundabout Guide
Peds threatened from afar by high-speed Red Light Runners Red lights Ped threatened from behind by left-turning vehicle Ped threatened from behind by right-turning vehicle Ped threatened by vehicle turning right on red
Pedestrian Conflict Points 4-way intersection 4-way IntersectionRoundabout 16 conflicts8 conflicts Source: FHWA Roundabout Guide
Pedestrian Conflict Points 4-way intersection 4-way IntersectionRoundabout 16 conflicts8 conflicts High Speed CrashesLow speed crashes Source: FHWA Roundabout Guide
Speed & Pedestrian Crash Severity
Pedestrian Crash Statistics Great Britain Source: FHWA Roundabout Guide
Bicycle Conflict Points 4-way Intersection Source: FHWA Roundabout Guide Conflicts in common with motor vehicles Conflicts unique to bicycles
Bicycle Conflict Points Roundabout Source: FHWA Roundabout Guide Bicyclist traveling as a pedestrian Bicyclist traveling as a vehicle
Bicycle Conflict Points 4-way intersection 4-way IntersectionRoundabout Left turn: 8 veh. confictsLeft turn: 5 veh. conficts Left turn: 2 ped conflicts Source: FHWA Roundabout Guide
Bicycle Conflict Points 4-way intersection 4-way IntersectionRoundabout Left turn: 8 veh. confictsLeft turn: 5 veh. conficts Left turn: 2 ped conflicts Through: 6 veh. conflctsThrough: 4 veh. conflcts Through: 2 ped conflicts Source: FHWA Roundabout Guide
Bicycle Conflict Points 4-way intersection 4-way IntersectionRoundabout Left turn: 8 veh. confictsLeft turn: 5 veh. conficts Left turn: 2 ped conflicts Through: 6 veh. conflctsThrough: 4 veh. conflcts Through: 2 ped conflicts High Speed, High Angle Crashes Low speed, Low angle crashes Source: FHWA Roundabout Guide
Bicycle Crash Statistics Great Britain Source: FHWA Roundabout Guide Crashes per million trips
Crash Statistics - France Source: FHWA Roundabout Guide
Crash percentage per type of user - France Source: FHWA Roundabout Guide
Crash Statistics - The Netherlands Source: FHWA Roundabout Guide Crash reductions by mode at intersections converted to roundabouts
“No design can be made idiot proof. ”
4-way Intersection 32 conflict points High speed impacts High angle impacts
Roundabout 8 conflict points 75% reduction in Motor Vehicle conflicts Low speed impacts Low angle impacts
Questions? Michael M. Moule, PE, PTOE (813)