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OHIO STATE EDITION
A Supplement to:
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6
4
71
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199 30 30 75
68
30 77
71 23 22 68
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70 70
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75
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November 9 2013
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Vol. XVIII • No. 23
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“The Nation’s Best Read Construction Newspaper… Founded in 1957.” Your Ohio Connection: Ed Bryden, Strongsville, OH • 1-800-810-7640
Treating I-270 Interchange Hot Spots With Diamonds By Lori Lovely
crashes, while fewer points of contact theoretically improve safety. However, because there were no DDIs in this country until June 2009, when the first opened to traffic in Springfield, Mo., there is no safety record available. Potential disadvantages of the DDI include driver unfamiliarity with the configuration and merging maneuvers on the left side of the road and the reversed flow of traffic. Exiting traffic cannot reenter the freeway in the same direction without leaving the interchange. This prohibits emergency vehicles from using the ramps to bypass crashes at the bridge, and oversize loads from using the ramps to bypass low bridges.
CEG CORRESPONDENT
Roberts Road over I-270 on the west side of Columbus, Ohio, was identified as a “hot spot location” — a 2 mi. (3.2 km) segment of the freeway or non-freeway with more than 250 crashes over three years. In addition, its bridges over the interstate loop needed new bridge decks and more clearance in order to meet federal highway standards. “The last major work on this section of roadway was in 1988, when an additional concrete layer was placed over the original 1967 pavement,” said Breanna Watzka, of the Ohio Department of Transportation. At that time, the mainline bridge decks also were overlayed. “The original subgrade constructed in 1967 had failed severely,” Watzka continued. “Existing roadway drainage had also failed over time. This led to numerous pavement failures and sunken concrete roadway slabs.” The 1988 bridge overlays were overdue for replacement, having exceeded their design life. This section of roadwork was originally planned for the early 2000s, but got passed over due to funding issues at the time. Instead, several “bandaid” projects were done to try to keep the road together during the 2000s prior to the start of this project. “The overall ride quality of this section of road was terrible prior to construction,” Watzka said. Because this section of road is a direct link for any oversize and overweight loads that are headed from Cleveland or Dayton to Cincinnati, it sees a lot of heavy traffic as these loads are routed from I-71 and I-70 around this sec-
Along with other projects around the state, this project is a testing ground for the concrete dowel bar inserter paving process. Additional work includes upgrading drainage, signing, lighting, vertical clearance improvements, and rehabilitation of overhead and ramp bridges. Designated bike lanes also will be provided.
tion of I-270 and then back onto I71 to Cincinnati. Diamond in the Rough ODOT’s highway safety programs focus on freeway and nonfreeway, high congested locations. Each year, the department prioritizes these locations for improvements using available funding. A mixture of federal and state funding will be used on the $81.5 million contract. Initially, ODOT presented four proposed alternatives to the public in November 2010. Based on comments from the public meeting and further evaluation, the diverging
diamond interchange (DDI) was selected because of its projections to eliminate all the congestion at the interchange, one of ODOT’s goals, along with improved safety. The diverging diamond interchange, also called a double crossover diamond interchange, was listed by Popular Science magazine as one of the best innovations in 2009 in the engineering category. It’s a type of diamond interchange in which the two directions of traffic on the non-freeway road cross to the opposite side on both sides of the bridge at the freeway. It requires traffic on the freeway overpass to briefly drive on
the opposite side of the road from what is customary. The diverging diamond interchange at Roberts Road/I-270 is intended to reduce congestion and improve traffic flow by switching traffic to the opposite sides of the road as it passes over the freeway and constructing entrance ramps to I-270 that are free-flow turns. Benefits include elimination of congestion and the need for arrows on traffic signals. Two-phase signals significantly reduce delay. In addition, by removing turn lanes, capacity is increased. Reduced horizontal curvature is thought to reduce risk of off-road
By the Numbers Construction began Aug. 22, 2011 and is scheduled for completion July 31, 2014, according to Watzka. “This project involves the reconstruction of pavement and mainline bridges for 7.02 mi. (11.3 km) of I-270 in southwest Columbus. The work also includes reconstruction of all ramps and widening the median and outside shoulders on I-270.” Additional work includes upgrading drainage, signing, lighting, vertical clearance improvements, and rehabilitation of overhead and ramp bridges. Designated bike lanes also will be provided. On the surface, it’s not a unique project, Watzka said. “The project is basically rip out the old and rebuild new. However, to stabilize the bad subgrade, the project did perform a 12-in. (30 cm)-deep cement stabilization using the existing subgrade material. While not unique, it’s not something we do on every project.” This led to an see ODOT page 5