| I-10 Twin Span Bridge | |
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The high-rise portion of the current I-10 Twin Spans under construction near the North Shore of Lake Pontchartrain, February 2009, with the old eastbound span also visible |
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| Other name(s) | The Twin Spans |
| Carries | 6 lanes of Interstate 10 |
| Crosses | Lake Pontchartrain |
| Locale | New Orleans and Slidell, Louisiana |
| Maintained by | LaDOTD |
| Total length | 5.4 miles (8.7 km) |
| Width | 60 feet (18 m) each span |
| Vertical clearance | 30 feet (9.1 m) and 80-foot (24 m) at the bascule bridge section |
| Opened | July 9, 2009 (eastbound) April 7, 2010 (westbound) September 9, 2011 (completed) |
| Daily traffic | 55,000 |
The I-10 Twin Span Bridge, known locally as the Twin Spans, consists of two parallel trestle bridges. These parallel bridges cross the eastern end of Lake Pontchartrain in southern Louisiana from New Orleans, Louisiana to Slidell, Louisiana. The current twin spans were constructed in the second half of the 2000s after the original bridges were extensively damaged by Hurricane Katrina in 2005. The first span opened to eastbound traffic on July 9, 2009.[1] On April 7, 2010, the second span was opened to traffic and the old twin spans were permanently closed to traffic.[2] The approaches to the westbound lanes were completed with a ribbon cutting ceremony on September 8, 2011 and the opening of all 6 lanes the next morning.[3] The original Twin Span bridges will be demolished in the near future, with portions being used for a public pier in Slidell, LA, and the rest as an underwater reef.[4]
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The original bridges were opened at a short ceremony on December 21, 1965[5] and were each constructed with 433 65-foot concrete segments. Each span was two lanes wide, and they had a clearance of 8.5 feet (2.6 m) for most of the bridge, with a 65 feet (20 m) clearance at the bascule bridge section.
After Hurricane Katrina on August 29, 2005, the old Twin Spans suffered extensive damage, as the rising storm surge had pulled or shifted bridge segments off their piers. The eastbound span was missing 38 segments with another 170 misaligned, while the westbound span was missing 26 segments with 265 misaligned. The damage to the Twin Spans and to U.S. Route 90 to the east left only one route into New Orleans from the east, the U.S. Route 11 bridge just west of the Twin Spans. The Louisiana Department of Transportation & Development (DOTD) accepted a bid of $30.9 million from Boh Brothers Construction Company on September 9, 2005 to reconstruct the bridges, starting with the less damaged westbound span. Phase 1 of the project was to reestablish two-way traffic on the eastbound span within 45 days. Scavenged bridge segments from the westbound span were used to fill in the gaps in the eastbound span. On October 14, 2005, the east span was reopened to traffic with one lane in each direction. Phase 2 of the project was occurring concurrently with Phase 1 and involved repairs to the westbound span. Prefabricated steel bridge spans were used on the westbound bridge in two areas to replace destroyed segments and segments used on the eastbound span. The west span reopened on January 6, 2006, returning four lanes of traffic to flow once again. Due to the prefabricated steel segments, there were both a 45-mile (72 km)-per-hour speed limit and weight restrictions on the westbound span. Additionally, the span was closed periodically for maintenance work, which is covered by Phase 3 of the original contract.
Following the extensive damages from Hurricane Katrina, it was decided that the old Twin Spans were too vulnerable to storm surge and that the long term solution would be to construct two new spans. Ground was broken on July 13, 2006 on the project which constructed two new bridges 300 feet (91 m) east of the old spans. This $803 million project constructed two three-lane bridges 30 feet (9.1 m) above the surface of Lake Ponchartrain, with an 80-foot (24 m) high rise near Slidell. Each span is 60 feet (18 m) wide, consisting of three 12-foot (3.7 m) lanes, and 12-foot (3.7 m) shoulders on each side.
The wider bridges eliminated the bottlenecking that occurred at both ends of the old bridges and also will be able to accommodate 50 percent more traffic than the old twin spans, according to the Louisiana Department of Transportation and Development.[6] The current bridges also feature traffic cameras and electronic message boards to alert motorists of any potential problems on the bridge, much like the Lake Pontchartrain Causeway bridge.
On October 30, 2008, as construction workers were preparing a form for a concrete pour, a girder collapsed sending 10 workers plunging into Lake Pontchartrain approximately 30 feet (9.1 m) below. One of the workers, Eric Troy Blackmon, who was tethered to the girder died in the accident.[7]
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