6/12/02

Cheryl Cobb, 334/844-4218

AUBURN RESEARCH SPED I-65 BRIDGE PROJECT IN BIRMINGHAM

AUBURN -- "The bridge is toast," weren't the words Fred Conway wanted to hear when he learned that an intense fire caused by an accident involving a fuel tanker truck had shut down the Interstate-65/I-59 interchange in Birmingham the Saturday after the start of the new year.

But when the smoke cleared it was apparent that the bridge carrying I-65 southbound traffic was, indeed, damaged beyond repair.

As the doom and gloom predictions of months of traffic gridlock began, Conway, head engineer for the Alabama Department of Transportation bridge bureau, joined other senior staff to evaluate their options.

The option they chose -- a design based on the use of high performance concrete girders and structure (HPC) recently showcased in a cooperative project with Auburn University -- set the stage for the opening of the I-65 south replacement bridge in record time.

The cooperative research effort is one of many highway related projects that fall under AU's Transportation Peak of Excellence -- one of seven high-priority areas of research identified by the university for emphasis.

The speed with which the Birmingham bridge was completed all began with an Auburn project that involved the replacement of a bridge crossing Uphapee Creek near Tuskegee that was badly undermined by stream scour. It was part of a nationwide effort, funded by the Federal Highway Administration, to advance the use of HPC.

The design and replacement of the Macon County bridge was coordinated by Conway and the research by Michael Stallings, professor of civil engineering in AU's Samuel Ginn College of Engineering

"Our goal was to evaluate the ability of area contractors to meet HPC specifications in a cost-effective manner and to test and showcase the performance of the materials under local conditions," said Stallings. "ALDOT chose to use their usual bid procedures. We worked with the agency to develop the contract specifications and during construction acted as technical advisors to ALDOT and the contractor. We also conducted research on the materials and the structure."

Throughout the construction process, Stallings' group monitored concrete properties such as compressive strength, creep and shrinkage and abrasion resistance. Girders were instrumented to monitor behavior from placement of concrete through long-term service under various types of loading.

"The results from the Uphapee project provided a comfort level with HPC technology that allowed us to make the leap on the I-65 project," says Conway. "I-65 represents the main north-south route through Alabama and carries approximately 140,000 vehicles per day," he said. "Having a bridge out in a major interchange is an emergency situation. The FHWA worked closely with us to secure funding and support."

As ALDOT maintenance crews and crews from a local contractor -- the Morris Group -- started the cleanup, the agency began to figure out how best to reroute traffic.

By Sunday, senior ALDOT staff had made the decision to replace and widen the entire three-span bridge. Five veteran bridge contractors were invited to bid on the project.

ALDOT engineers were given seven days to prepare the plans for a structure that would employ the HPC technology similar to that showcased on the Uphapee Creek project. They worked closely with the contractors and Sherman Prestress of Pelham, the girder maker involved in the Uphapee project, to develop the concrete mix and girder design specs. The design was ready in six days.

"The decision to use pre-stressed high-strength concrete girders and concrete mix was initially driven by our tight timeline," said Conway.

The new HPC attains early strength, greatly decreasing production time, said Conway. As a result, pre-stressed concrete girders could be delivered to the site before steel fabricators could even procure material and begin fabrication of steel girders -- the other girder option considered.

It also meant that time would be saved at each phase of construction. The specifications called for a concrete that attained the same strength in 14 days as conventional concrete attained in 28.

"We were able to save two weeks of time at each phase of the project, resulting in an overall time savings of close to two months," says Conway.

In addition, the concrete girders allowed the engineers to extend the length of the bridge by 20 feet without a loss of strength or a major regrading of the site -- a costly and time-consuming task.

"The Uphapee experience convinced us that HPC was not only the best way to go because of the tight timeline but that it would also provide superior durability and lower maintenance costs than the traditional steel girder structure," says Conway.

Contract specifications were ready on Jan. 14. They included a penalty of $25,000 per day for late completion and an incentive of $25,000 per day for early completion. Construction time was set at 90 days.

On Jan. 16 the low bid was awarded to a joint venture between The Morris Group and Brasfield & Gorrie. Work began on Jan. 21 and was completed on Feb. 25 -- 37 days later and 53 days after the accident.

Conway said the $1.3 million in incentives earned by the contractor (the largest such incentive paid by ALDOT) were more than offset by the savings related to traffic rerouting and project management. In the end, the total project cost was still less than the next lowest bid.

"This project reinforced the importance of teamwork, speedy and clear communications, and of basic research," says Conway. "Were it not for the groundwork done by Auburn at Uphapee Creek, construction times would have been much longer and the construction costs much higher. The resulting structure would not be as long-lived as the one we have today."

"ALDOTıs relationship with Auburn has been a long and productive one," says Conway. "We are excited about the expanded efforts under the Transportation Peak and look forward to continued cooperative efforts."

jun02:AU:bridge