OR126/Tom McCall

Intersection Improvements

August 2, 2016

Traffic Engineering Analysis

Operational Analysis– Utilize Highway Capacity Manual

• Volume-to-capacity ratio• Delay• Level-of-service• Queues

Safety Analysis– Utilize Highway Safety Manual and supplementing research

• Crashes per year• Severity

Existing Intersection Operations

Existing Intersection Safety Performance

5 years of historical crash data– Total Number of Crashes: 12– Total Injuries: 12

How does a roundabout compare to a signal?Year 2035 Operations – Average Delay per Vehicle

> 80s

~ 29s (With left-turn lanes)

29s (Single-lane roundabout)24s (With NB right-turn lane)

OR126/Tom McCall

Vehicle stackingQueues are approximately half as

long with roundabout vs. signal

How does a roundabout compare to a signal?Future Safety Performance over 5 Years

6.5 Total Crashes 3.4 Fatal/Injury

3.6 Total Crashes 3.3 Fatal/Injury

1.9 Total Crashes 0.4 Fatal/Injury

71% reduction87% reduction

OR126/Tom McCall

44% reduction3% reduction

Questions?

73’

130’

112’

113’

73’

Roundabouts reduce crashes

Over 90% reduction in fatalities 76% reduction in injuries 35% reduction in total crashes

* NCHRP Report 572

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Safety Performance (NCHRP Report 572)

78% reduction in injuries 48% reduction in total crashes

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