Bridge D-a-s-h-e-r-s

Feb. 1, 2006

The state of Ohio has the second largest number of bridges in the U.S. and the seventh largest highway system. Like many states, portions of the system are outdated, overburdened and in need of repair. Many areas of the Buckeye State are becoming highly populated and developed, resulting in increased traffic volumes.

The state of Ohio has the second largest number of bridges in the U.S. and the seventh largest highway system. Like many states, portions of the system are outdated, overburdened and in need of repair. Many areas of the Buckeye State are becoming highly populated and developed, resulting in increased traffic volumes.

The additional motorists on the roadways necessitate adding lanes on many of the routes. To accomplish this task, road crews have to close or restrict lanes during the construction process. Such closures and restrictions negatively affect motorists in terms of lost time, higher fuel costs and lost revenues. The Ohio Department of Transportation (ODOT) is committed to the continuous movement of traffic through all work zones by the elimination or reduction of delays.

In 2003, ODOT replaced an aging bridge on U.S. Rte. 22 over the Scioto River—just west of Circleville, approximately 30 miles south of Columbus. The existing 630-ft-long structure was a 45-year-old concrete-slab-on-steel-stringer bridge. It was a six-span structure—90-ft approach spans with 112-ft 6-in. main spans—consisting of four girders supported by concrete hammer-head piers. The three western spans bridged the main channel of the river, while the remaining spans bridged the river flood plain. The deck was 29 ft 4 in. wide, accommodating a two-lane roadway and 3-ft-wide sidewalks on both sides.

The existing structure was in need of replacement because of severe deterioration of the girders and to provide a wider roadway that would accommodate local farm equipment and the ever-increasing traffic.

The U.S. Rte. 22 bridge is used by more than 10,000 vehicles per day. Using conventional, phased construction, the bridge would have been restricted to one lane for up to 18 months. Because of the narrow width of the existing structure, the work zone would not have been able to accommodate most farm equipment, trucks and emergency vehicles. These vehicles would have been forced onto the posted detour.

In 2001, ODOT benchmarked with other states that were utilizing various types of accelerated bridge construction techniques. Using some of these ideas under ODOT’s new “Fast Track” bridge program, the bridge was completed and opened to traffic in 48 days. This was one of Ohio’s first and largest fast-track bridge projects to be completed.

The project was sold as design-build to encourage the bidders to develop a design that would minimize construction time. Some of the techniques the project incorporated to reduce time included prefabricated materials, stay-in-place forms, high-performance materials and contractor incentives and disincentives to speed the pace of construction.

Smile for the camera

In August 2002, ODOT released a preliminary scope of work to potential bidders through the Ohio Contractors Association. On Sept. 12, 2002, ODOT held a pre-bid meeting for interested contractors and consultants, and the bid package was released during the last week of September. Bids were due Dec. 6, 2002.

The winning bid was submitted by and the contract awarded to a design-build team of the Ruhlin Construction Co. and E.L. Robinson Engineering Co. The final design of the replacement structure was 44 ft 2 in. wide and consisted of five girders, instead of four, fabricated from high-performance steel supporting a metal stay-in-place deck-forming system. The girders were designed as simple spans to simplify erection but were made continuous during construction by pouring integral concrete diaphragms over the piers. The abutments also were designed integrally, resulting in one of Ohio’s longest bridges without expansion joints.

Reconstruction of the bridge was a major event for the residents of Circleville. It was recognized from the start that community relations was an important aspect for this project. Several articles documenting the progress of construction were published in local newspapers throughout the life of the project and a live web cam was installed on site so that anyone with Internet access could monitor the progress. This camera also proved very useful for ODOT personnel and the members of the design-build team for documentation of the project.

Fabrication of the steel is often one of the most critical tasks in steel projects with regard to the scheduling. With this in mind, the design-build team created a relationship with Stupp Bridge of Bowling Green, Ky., early in the planning process.

The posted detour was approximately 20 miles long and required a left turn off of a heavily traveled road at an intersection without a traffic signal. ODOT decided to install a signal at this intersection to relieve traffic congestion and improve the overall safety of the detour. Additionally, informational signs were placed at strategic locations throughout the county to help through traffic avoid the construction site and the detour altogether.

A second detour route was available to motorists familiar with the secondary roads in the area. This second route, although much shorter than the posted detour, required crossing a single-lane, load-rated truss bridge that was constructed in 1913. This was recognized as the local detour for vehicles that were under the load restrictions.

A final concern regarding the detoured traffic centered on response times for emergency personnel. The fire and emergency medical services (EMS) located in Circleville are responsible for a substantial area west of the construction site. The secondary route, with load-rated restrictions, did not permit the fire trucks to cross. EMS was able to utilize the secondary route without weight restrictions, but after further review this detour would add several minutes to response time. To help mitigate this situation, the fire and EMS crews established a temporary station west of the bridge closure. ODOT provided funding for this additional EMS site. Four calls were responded to during the bridge closure.

Beginning the end

The bridge was closed to traffic promptly at midnight on June 16, 2003. The crews worked two shifts, night and day, for two weeks during the demolition. They started saw-cutting the existing deck into manageable sections, torch-cutting the existing handrail and 3-ft metal sidewalk on the north and south side of structure. At the same time the contractor started driving piles on the south side of the structure. The extended portion of the replacement piers was supported by groups of four 18-in. cast-in-place galvanized piles that were driven and capped with concrete. The steel piers and piles were galvanized to reduce corrosion, because during periods of high water they will frequently be submerged.

After the new piles were in place for each pier, the existing concrete deck was removed with track hoes and loaders. The demolition started in the middle of the bridge and proceeded toward the abutments. This process was necessary due to environmental restrictions. The contractor was not allowed to work in the river or place cofferdams. All work had to be done from the existing deck and the northeast side of the stable flood plain area. Sections of the existing deck were placed on the northeast side of the bridge and used to provide a stable base for the crane to safely operate. The existing girders were torch-cut from a man basket and removed with two cranes, one crane placed on the west side approach and the other on the northeast side of the structure.

From a boat, the contractor formed a falsework platform around the three piers that were in the river. The falsework helped the crews with the time-consuming task of saw cutting the pier caps and stem.

Once the caps with stem were cut, a hole was drilled through the cap to allow the cranes to pick the caps with secure cables and not disturb the river. As the tops of the piers were removed, the cut surfaces were prepared with a self-leveling grout. After the grout cured, a template was placed on the surface to show where to pre-drill holes for the steel replacement pier bolts. The galvanized steel-plate girder caps were placed and extended outward to the south side where they were supported by the groups of four galvanized piles with a concrete table top cap.

As the new steel-plate girder caps were completed, working from east to west, the girders were delivered and installed. The girders were designed as simple spans to speed erection and were subsequently made continuous by pouring integral diaphragms over the piers.

Smooth finish

After the girders were placed, prefabricated supports, known as “ladders,” were installed. These ladders consisted of pairs of parallel angles connected by bar stock intended to straddle the top flanges of the girders and support the ends of the stay-in-place forms. The design-build team saved substantial time prefabricating the ladders, since the girder profiles were known in advance. In rehab work utilizing existing girders, the contractor must wait until the existing deck is removed to obtain the in-situ profile of the girders.

After the deck reinforcing steel was installed and the concrete screed was assembled, the deck was poured working from west to east. The concrete placement started at sunset and was completed at sunrise. Two concrete pumps were used during the deck pour. One pump was placed on the west side of the structure and the other on the northeast side of the structure. This arrangement saved the time that would have been spent waiting for the pump to drive the detour to relocate to the east side. The approach slabs and diaphragms were poured continuous with the deck.

The parapets were placed using a slipform machine approximately seven days after the completion of the deck pour. The north parapet is located at the edge of the deck while the south parapet separates the roadway from the pedestrian walkway. A chain-link fence serves as the outside border for the walkway.

The construction crews worked through several moderate to severe thunderstorms but encountered no significant problems. Excessive rain did, however, lead to major flooding of the river several times.

The financial incentive for the contractor to complete work quickly was accomplished by incorporating a liquidated savings/liquidated damages clause to the contract. The liquidated savings allowed for payments to the contractor of $50,000 per day for each day the project finished early. The total incentive was capped at $500,000. The liquidated damages were graduated from $20,000 to $50,000 per day for each day over 60.

The contractor finished the work in 48 days and collected the full $500,000 bonus without a single lost-time injury.

The bridge was completed quicker than any project of its type in Ohio history. Motorists as well as ODOT consider this “Fast Track” design-build project a great success, and since the completion of the U.S. Rte. 22 bridge, ODOT has implemented this innovative contracting technique on other bridge replacements.

About The Author: Howell is a project coordinator at the Ohio DOT. She can be contacted at 740/833-8261; e-mail: [email protected].