Transcript PowerPoint Module 3 Safety Considerations

Roundabouts in the United States
Module 3
Safety Considerations
Safety benefits of roundabouts
Research has shown there are many safety benefits associated with
roundabout intersection design.
Safety is a major consideration on our highways and roadways
PHOTOGRAPHY SOURCE: Fred Ranck
In the year 2003 there were an average of 6,850 motor vehicle crashes
per day at intersections in the United States.
For transportation professionals, safety is a major concern.
Roundabouts in the United States
Module 3—Safety Considerations
Intersections are the scene of many accidents.
PHOTOGRAPHY SOURCE: Fred Ranck
Transportation professionals are always looking for ways to reduce the
number and severity of crashes.
Roundabouts in the United States
Module 3—Safety Considerations
What is the effect on crash rates after an intersection is
converted to a roundabout?
Conventional 4-way Intersection
Roundabout
1122
726
Data from 55 intersections with at least 2 years of crash data before
and after conversion of the intersection to a roundabout.
Roundabouts in the United States
Module 3—Safety Considerations
What is the effect on severe injury rates after an intersection is
converted to a roundabout?
Conventional 4-way Intersection
Roundabout
296
72
Data from 55 intersections with at least 2 years of crash data before
and after conversion of the intersection to a roundabout.
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
Urban Signalized Intersection
Roundabout
35
14
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
Suburban Signalized Intersection
Roundabout
292
98
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
AWSC intersection
Roundabout
17
13
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
Rural TWSC intersection
Roundabout
248
71
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
Suburban TWSC intersection
Roundabout
358
245
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of crashes compare between conventional
intersections and roundabouts?
Urban TWSC intersection
143
Roundabouts in the United States
Roundabout
102
Module 3—Safety Considerations
Typical types of crashes at roundabouts
Entering
Roundabouts in the United States
Module 3—Safety Considerations
Typical types of crashes at roundabouts
Exiting
Roundabouts in the United States
Module 3—Safety Considerations
Typical types of crashes at roundabouts
Examples of Loss of Vehicle Control
Roundabouts in the United States
Module 3—Safety Considerations
Typical types of crashes at roundabouts
-35%
TOO FEW
Roundabouts in the United States
-76%
-60%
-67%
TOO FEW
SIMILAR
SIMILAR
-72%
-32%
-29%
-87%
-71%
-81%
Module 3—Safety Considerations
Bicycle and Pedestrian Considerations
PHOTOGRAPHY SOURCE: Lee Rodegerdts
Intersections also introduce concerns for transportation professionals
on the safest way to accommodate pedestrians and cyclists.
Roundabouts in the United States
Module 3—Safety Considerations
Pedestrian Considerations at Roundabouts
PHOTOGRAPHY SOURCE: Lee Rodegerdts
Data on pedestrian/motor vehicle crashes is very limited.
Roundabouts in the United States
Module 3—Safety Considerations
How do typical types of pedestrian/motor vehicle crashes
compare between conventional intersections and roundabouts?
PHOTOGRAPHY SOURCE: Lee Rodegerdts
Motor vehicles conflict with pedestrians in the crosswalk areas and can
occur as the vehicles enter or leave the intersection from several
different directions.
A roundabout allows a pedestrian to observe motor vehicles from one
direction at a time as they cross the travel lanes.
Roundabouts in the United States
Module 3—Safety Considerations
PHOTOGRAPHY SOURCE: Lee Rodegerdts
Pedestrian Considerations at Roundabouts
“Personally, I love them, . . . you only have to
stop one lane of traffic, then go to the middle
and wait. The cars can’t go much faster than 20
mph through the roundabout so the crossing
aspect is great”
From the Howard-Suamico—Denise Haltom,
School Crossing Guard, Suamico, Wisconsin
Roundabouts in the United States
Module 3—Safety Considerations
PHOTOGRAPHY SOURCE: Lee Rodegerdts
Bicycle Considerations
Roundabouts in the United States
Module 3—Safety Considerations
Cyclist Movements at Roundabouts – Circulating as a Vehicle.
Bike lanes are not recommended within a roundabout. Instead, cyclists
merge with traffic before entering the roundabout, circulate with
traffic, and then re-enter the bike lane after exiting.
Bikes re-enter
bike lane
Fewer conflict
points with
motor vehicles
Lower motor
vehicle speeds
(15-20 mph)
Bikes merge
with motor
vehicles
Roundabouts in the United States
Module 3—Safety Considerations
Cyclist Movements at Roundabouts – Circulating as a Pedestrian.
If a cyclist is uncomfortable riding with traffic, a cyclist can choose to
travel instead as a pedestrian.
Bikes return
to bike lane
Bicyclists
cross as
pedestrians
Bikes join shared
path with
pedestrians
Roundabouts in the United States
Module 3—Safety Considerations
Summary of the Safety Features of Roundabouts
PHOTOGRAPHY SOURCE: Lee Rodegerdts
• Travel speeds generally reduced by traffic
calming effects
• In almost all cases, the total number of
crashes is reduced when a conventional
intersection is replaced with a roundabout
• And more importantly, the number of
severe injury crashes is dramatically
reduced due to the roundabout’s common
direction of travel and similar speeds
Roundabouts in the United States
Module 3—Safety Considerations