South Salem Off-ramps

South Salem Off-ramps
Final Presentation
CE450 Traffic Safety Analysis
Department of Civil and Env. Engr.
Team members:
Chris Goya
Joe Strobel
Justin Willard
Project Overview
Two southbound off-ramps
Queuing problems at Kuebler
Difficult access to south
Commercial
Kuebler off-ramp
Kuebler off-ramp
Southbound on/off-ramp
Existing
Proposed
Northbound on/off-ramp
Existing
Proposed
VISSIM Model Results
Existing versus Proposed
designs
Future ADTs used for
volumes
Modeled with a fixed time
controller and a ring barrier
controller
Travel time decreases:
Fixed time
16.2%
Ring barrier
14.9%
Stopped delay decreases:
Fixed time
13.7%
Ring Barrier
24.8%
Safety Analysis
9 out of 10 crashes were
rear-end
6 of 10 crashes occurred
during pm peak
Reduction of rear-end
crashes with proposed design
Safety Analysis
Which CMF applies?
CMF of 0.77 for all crash types
(Maze, 2010)
CMF of 0.55 for injury crashes
23% reduction for all crash types
Cyclist and Pedestrian Needs
Two cyclists and two pedestrians used
intersection during two hr. period
Proposed change would give right lane
free access
How do you accommodate cyclists and
pedestrians?
Soutbound Commercial Off-ramp
Off-ramp for southbound
I-5 traffic to Commercial St.
Geometric curve and
elevation concerns
Off-ramp would alleviate
traffic for the previous
Kuebler off-ramp
Proposed Preliminary Design
Design Speeds
Horizontal curve
ODOT’s Highway Design
Manual was referenced
(chap. 9)
65 mph freeway: 35 mph offramp min. design speed
35 mph design speed: max.
curve of 19°
R=10°
R=19°
45 mph design speed: max
curve of 10.5°
Superelevation
Superelevation for 19° curve:
12%
Superelevation for 10° curve:
11%
Existing site superelevation:
7 to 10%
Vertical Grade
Ascending vertical curve 35
mph design speed: 6%
Descending vertical curve 45
mph design speed: 6%
Existing site grade at a max.
of 7%~
May need to soften the grade
by building up the ramp
downhill
Conclusions
Commercial St. off-ramp:
Site appears well-suited to
provide an off-ramp with
minimal earthwork needed
Kuebler Blvd. off-ramp:
Reduction in total
intersection delay of 15%~
Questions?
Questions?