Louisiana DOTD Drops Plans to Build Couplet to Solve Thibodaux Traffic Woes

Wed November 09, 2005 - Southeast Edition
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The Louisiana Department of Transportation and Development has dropped plans to upgrade traffic flow through Thibodaux using a “couplet,” or one-way pairing system between LA 1 and LA 308.

Secretary Johnny B. Bradberry sent a letter announcing DOTD’s decision to the Thibodaux City Council in October.

He said the department opted for its “no-build” option, a rare occurrence, for two reasons. The first was the Lafourche Parish Council’s opposition to the couplet concept. The second was the Thibodaux City Council’s support only if four new bridges were included rather than the two planned and budgeted for in Phase 1.

Discussions have been under way since as early as 1994 on how to improve traffic flow through Thibodaux in Lafourche Parish. LA 1, known as St. Mary Street in Thibodaux, lies on the natural levee of Bayou Lafourche. LA 308, or Bayou Road in Thibodaux, lies parallel on the other side of the bayou. Six bridges provide access from one to the other.

Both highways are emergency evacuation routes for the parish and also get heavy recreational and commercial/industrial traffic to Grand Isle and Port Fourchon.

DOTD considered three alternatives:

• Widening LA 1 to add one two-way, left-turn lane, for a total of three lanes

• Widening LA 1 to add three lanes, for a total of five. Two lanes would travel in each direction, with the center lane used as a two-way, left-turn lane

• Changing the travel pattern to have LA 1 become one-way eastbound while LA 308 would be one-way westbound, known as a “couplet.”

After assessment and traffic studies in 1996 and a supplemental traffic study in 1997, the department concluded that only the couplet alternative would provide an acceptable level of service through the life of the project (2020).

The LA 24 couplet system, between Thibodaux and Houma in Terrebonne Parish, was fully implemented around 1995 and was considered a success by the DOTD.

The department proposed having the couplet end at the existing bridges at LA 3185 and Percy Brown Road/La. 648 Spur. Phase 1 would have included construction of two fixed bridges within the couplet area — one to the west on Ridgefield/Coulon Road and the other to the east on Davis Drive. This phase also would have realigned a dog-leg section of LA 1 from SP Drive to Jackson Street. The total cost of this phase, for which funding had been programmed, was $2.5 million.

During Phase 2, DOTD proposed to build two new bridges as new terminal points to the couplet. The couplet would have been extended about a half-mile west of the LA 3185 bridge and to the east of the Percy Brown Road bridge, and new bridges constructed at those points.

Bradberry suggested that the City Council consult with the South Central Planning Development Commission, of which the council is a part, to pursue traffic flow improvements. Another option would be to seek a specific request at annual legislative hearings.

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