Hurricane Rita may have slowed down progress on the reconstruction of the Interstate 10 twin span over Lake Pontchartrain, but its too early to tell. On Sept. 22, crews began demobilizing in preparation for the second hurricane to threaten New Orleans within a month. They probably wont finish remobilizing until Sept. 25, said John Horn, vice president and project engineer for David Volkert & Associates Inc., the Mobile, Ala.-based consulting engineer hired as the Louisiana Dept. of Transportation and Developments on-site representative. Damage caused by Rita was nothing compared to the original devastation caused by Katrina. We had one span that was teetering on the edge of the bent and it fell off, Horn said. We wouldnt have used that one anyway because there wasnt any way for us to lift it back into place.

Andrew Mancuso, assistant construction manager, prepares to coordinate barge-mounted crane pick. (Photo: Angelle Bergeron for ENR)

Lost time is probably the biggest consequence of Rita. We had to move our equipment to safe harbor, said Al Flettrich, bridge division manager for Boh Bros. Construction LLC, the New Orleans-based repair contractor. We were granted an extension of four days. Except for this all is going well and we are on schedule. Flettrich added that the bridges sustained additional damage from Hurricane Rita. The contractor and state inspectors were performing an assessment on Sept. 27.

On September 12, the 45-day clock started ticking on a $30.9-million emergency repair contract to rebuild the eastbound bridge of the I-10 twin span over Lake Pontchartrain that was rendered impassable by Hurricane Katrina.

"Basically, when the storm moved into the lake, the water rose, air pockets formed under the bridge and floated the spans off the caps," said Flettrich. Boh Bros. won the public bid to repair one span and construct a temporary steel bridge to replace the other span until new, permanent structures are built.

Because the storm entered Lake Pontchartrain from the east, winds coming from the north-northwest combined with the elevated water levels to batter the bridges until they slid off the girding pads, hitting adjacent pedestals, said Horn. That explains why the westbound bridge suffered the most damage. Some of the spans floated just a little, and some came completely off the caps, said G.J. Schexnayder, field project manager for Boh. On the eastbound side, 38 spans fell off and 170 were misaligned. The westbound was worse, with 20 spans missing and 303 misaligned.

Additionally, 13,000 ft of barrier railing is missing from the westbound span, which is why Volkert targeted the eastbound span for repairs first. Were cannibalizing good spans from the westbound bridge and putting them on the eastbound to make a complete bridge, Flettrich said. Boh hired HNTB Corporation of Kansas City, Mo., to consult on the design for bearing pads, missing cap piles and alignment procedures, he added.

Boh will use two procedures to realign spans. The first involves two hydraulic steerable trailers, which are set on a barge and positioned beneath the spans. Sliding plates are placed underneath the span, which is lifted and moved back into place, explained Andrew Mancuso, assistant construction manager. Using the steerable trailer gives us a little more maneuverability so we dont have to rely on that tug captain with a barge between two bents, Mancuso said. We can maneuver the span around on top of the barge itself.

Hurricane Katrinas surge formed air pockets that floated spans from their caps, inspectors say. (Photo: Angelle Bergeron for ENR)

The second method that will be used to realign spans is a jack-and-slide system. This involves placing Teflon plates on the underside of the span and jacking it up from underneath. At the same time, hydraulic rams, positioned on top of the spans and braced against the curbs of the adjacent spans, nudge the spans into alignment. Were trying to do what we can to get it done, Mancuso said.

To pick the spans from the westbound bridge, Boh is using a Manitowoc 4600 crane with spreader bars that have been specially rigged to increase the traveling block. Although the technology has been used in other areas of construction, it is certainly a first for bridge repairs, Horn said. It hasnt been done so much to realign bridges because we havent had that many circumstances where bridges were knocked off their foundations. I dont know of any situation where you have had hundreds of spans knocked out of alignment.

To pick the spans from the westbound bridge, Boh is using a Manitowac 4600 crane with spreader bars that have been specially rigged to increase the traveling block. Although the technology has been used in other areas of construction, it is certainly a first for bridge repairs, Horn said. It hasnt been done so much to realign bridges because we havent had that many circumstances where bridges were knocked off their foundations. I dont know of any situation where you have had hundreds of spans knocked out of alignment.

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  • These bridges fared much better by comparison than those over Escambia Bay, Horn said. Over there, we had a substantial amount of substructure damage, and we replaced a lot of pilings and bents, he said. On this one, the substructure is in good condition and we think we will only have to replace one of the bents.

    Everyone is hoping Boh finishes the job early. The DOTD is offering a $75,000 daily incentive/late penalty for the job. There is a 15-day ceiling on how much they get extra but, if they get it done within 30 days, they will get $1,125,000 extra, said Mark Lambert, communications director with the DOTD. Its a 24/7 job now, and its going well.

    Many people are anxious to see the twin spans reopened. Although LADOTD has no average daily traffic count on the twin spans, in 2004 the department did record 55,439 vehicles eastbound I-10 between I-510 and the Highway 11 Bridge at ADT. Presumably, the lions share of the traffic traversed the larger, newer twin spans instead of the Hwy. 11 Bridge.

    With the route out of commission, motorists desiring access to Orleans parish must travel across the older, one-lane Hwy. 11 Bridge and take Highway 90 into the eastern part of the city, take the Causeway through Jefferson Parish or travel the perimeter of Lake Pontchartrain. The route entails passage, for at least part of the journey, along I-12. Evacuees that are seeking temporary refuge in Baton Rouge have nearly doubled the population of the capitol city and placed an added burden on I-12, which is almost constantly jammed with traffic.

    With the route out of commission, motorists desiring access to Orleans parish must travel across the older, one-lane Hwy. 11 Bridge and take Highway 90 into the eastern part of the city, take the Causeway through Jefferson Parish or travel the perimeter of Lake Pontchartrain. The route entails passage, for at least part of the journey, along I-12. Evacuees that are seeking temporary refuge in Baton Rouge have nearly doubled the population of the capitol city and placed an added burden on I-12, which is almost constantly jammed with traffic.

    When Flettrich detailed the sequence of events leading up to Bohs mobilization, he made an unconscious commentary on the situation. The DOTD sent out the proposal on the 7th, and we bid it on the 9th, Flettrich said. We signed a contract that night at 5 p.m. We would have signed it sooner but we got caught in traffic.

    Once the eastbound span is completed and open for traffic, Boh will begin the 75-day contract for construction of a westbound, temporary steel bridge. A lot of this will be subject to federal regulations, but right now, our plan in the first quarter of 2006 is to let a contract for an elevated replacement bridge, DOTDs Lambert said.