|
 Preliminary
Recommendations (Summary)
I. Introduction
Over the past several months, the Ohio Department of
Transportation has been conducting an analysis of eight concepts
that may help reduce accidents and congestion on the Interstate 270
North Central Outerbelt between State Route 315 and Interstate 71.
The concepts were identified and evaluated based on
input from the public and an Advisory Committee made up of community
and business representatives. The evaluation criteria placed
importance on reducing congestion and accidents, minimizing
environmental and community impacts and maximizing cost
effectiveness.
II. Background
Today, the North Central Outerbelt in Columbus is the fourth
most congested, high-crash freeway location in Ohio – serving
about 180,000 vehicles per day and experiencing 542 accidents per
year.
The interchanges at S.R. 315, U.S. 23 and I-71 were
built in the ‘60s and serve about 10 to 20 percent more traffic
than they were designed to handle. The outdated design and the close
proximity of interchanges, particularly at S.R. 315 and U.S. 23,
cause excessive driver weaving and merging that create congestion
during peak hours and contribute to hundreds of accidents each year.
About 36 percent of all crashes occur during the
evening rush hours between 3 p.m. and 7 p.m. and 42 percent of the
crashes are rear-end collisions, which is typical of stop-and-go
traffic.
III. Summary of Recommendations
State Route 315 Interchange
Recommended: Replace "loop" ramps with flyover ramps
that reduce weaving and merging.
ODOT recommends Alternative 1, which would replace
loop ramps at S.R. 315 south to I-270 east and S.R. 315 north to
I-270 west with flyover ramps that reduce almost 80 percent of
weaving and merging at the interchange.
Loop ramps located in adjacent quadrants at an
interchange cause intense weaving because motorists exiting and
entering a highway must share a lane. As traffic volume grows higher
at the interchange, this weaving leads to congestion and accidents.
Flyover ramps reduce weaving and accommodate higher speeds by
separating different traffic movements and flattening curves. Loop
ramps have tighter curves and slower design speeds.
Other improvements include:
-
Improving the safety of the I-270 ramps to S.R.
315 south by flattening the curve to better accommodate
high-speed travel. The lane configuration would also be changed
to eliminate merging at the ramps before joining S.R. 315.
-
Creating dedicated lanes and ramps that separate
through traffic on I-270 east from ramp traffic to and from S.R.
315 and U.S. 23.
Not Recommended: ODOT also analyzed a similar
concept called Alternative 2, which would replace the same loop
ramps using a different flyover ramp design with more sweeping
curves. This concept operated equally well compared to Alternative
1, but it was more costly and time consuming to build, and had more
environmental impacts.
U.S. Route 23 Interchange
Recommended: Replace exit "loop" ramps with a ramp design
that brings traffic to a signalized intersection.
ODOT recommends Alternative 1, which would reduce
nearly 90 percent of the weaving and merging by replacing the exit
ramps from I-270 west to U.S. 23 south and I-270 east to U.S. 23
north. Instead, the ramp design would eliminate the loops and bring
traffic to a signalized intersection on U.S. 23. The ramp design
would be similar to the Sawmill Road interchange, except there would
be two signalized intersections instead of one.
Other improvements include:
Not Recommended: ODOT also analyzed a similar
concept called Alternative 2, which would replace the entrance loop
ramps from U.S. 23 to I-270 with a directional ramp that merges with
oncoming traffic. This concept is not recommended because it would
not reduce weaving and merging, which contributes to congestion and
accidents.
U.S. Route 23 North
Recommended: Separate through and local traffic by creating
northbound express lanes down the center of U.S. 23
The U.S. 23/I-270 interchange cannot be fixed
without addressing the bottleneck on U.S. 23 north of the
interchange. ODOT recommends Alternative C, which would eliminate
all weaving and merging by separating through and local traffic. In
addition, the design would accommodate future traffic growth well
beyond 2028.
The concept would construct two through lanes
northbound in a trench down the center of U.S. 23, which would allow
traffic to bypass signalized intersections. Two lanes for local
traffic would be maintained on the outside, with caps at the
intersections for turn lanes.
Not Recommended: ODOT also analyzed two other
alternatives. Alternative D would separate through and local traffic
by placing through traffic on elevated structures through the
corridor. The design is not recommended because it would require
multi-span bridges and piers, which would complicate turning
movements and reduce sight distance.
In addition, ODOT analyzed Alternative A, which
would add an additional lane in each direction on U.S. 23. This
design was not recommended because it would not reduce merging and
weaving on U.S. 23, which contributes to congestion and accidents.
Interstate 71 Interchange
Recommended: Replace the "loop" ramp from I-270 east to
I-71 north with a flyover ramp.
Replacing the ramp will eliminate 100 percent of the
weaving and merging and nearly all of the congestion at the
interchange.
Other improvements include:
-
Improving the safety of the I-71 ramps to I-270
west by flattening the curve to better accommodate high-speed
travel. The lane configuration would also be changed to
eliminate the inside merge as the ramp joins I-270.
-
Increasing the capacity of I-270 west to I-71
north by widening the ramp to two lanes.
IV. What's Next?
ODOT will continue to solicit public input on these
recommendations over the next month. Final recommendations will be
made in March.
The preferred alternatives will then advance to
further preliminary engineering and environmental screening, before
moving to detailed design and construction. The estimated cost of
construction is between $150 and $200 million. Construction on the
I-71 interchange could begin as early as 2006. Construction on the
S.R. 315 and U.S. 23 interchanges and U.S. 23 north could begin in
2008.
Preliminary
Concepts Alignment Presentation (Aerial Views) :
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