Project Overview
In the low-lying river delta of Port Sulphur, La., a major liquefied natural gas (LNG) export facility faced a complex challenge: transporting cryogenic LNG at temperatures around -260°F from storage tanks to a marine terminal nearly half a mile away. The solution required a 2200-ft-long pipe bridge spanning swamp terrain and a highway, with structural demands that included seismic resistance, blast protection, and extreme thermal movement. Originally designed as a cast-in-place concrete system, the bridge’s substructure was re-evaluated early in development, with precast concrete becoming the clear choice for the effort.
Super Bents, Super-Fast
Tindall Corporation, which had already engaged with the owner on additional site infrastructure, proposed a design-build solution for the bridge’s substructure bents. Partnering with KBR | Zachry, the general contractor and engineer of record, Tindall developed an emulative precast concrete design that met all performance requirements—including Federal Energy Regulatory Commission approvals—while cutting weeks off the timeline. The system leveraged grouted couplers and proprietary advancing bar connectors to eliminate closure pours and simplify assembly.
Two massive, 700-ton super bents support the 260-ft highway span. Each super bent includes segmented beams and columns weighing up to 52 tons apiece. Using mass grouting and innovative connections, crews installed the behemoth bents without scaffolding or mixer trucks, which was critical to supporting a project in a remote location with limited access. This fully grouted, super-bent-supported precast concrete assembly for accelerated bridge construction is a first in North America.
Because the pipe bridge was located on the critical path for plant commissioning, speed was everything. Sole plates—massive bearing components embedded deep into the beams—were detailed, fabricated, and galvanized in less than a week to stay ahead of schedule. Once pile caps were ready, the team averaged one bent installation per day. Grout reached design strength in less than 48 hours, allowing steel bridge modules arriving by barge to be set immediately. In total, 128 precast concrete components traveled 700 miles to the site, including 23 bents.
Pivoting from cast-in-place to precast concrete proved to be a game changer. The approach reduced site labor, improved safety, and allowed precise coordination in a challenging environment. By combining emulative design with smart connection systems, the team delivered a critical piece of the $12-billion LNG export facility on time and under budget, positioning this key element of Louisiana’s infrastructure up for long-term success and reliability with the power and versatility of precast concrete.
Mason Nichols is a Grand Rapids, Mich.-based writer and editor who has covered the precast concrete industry since 2013. |