(Dave Duke/DelDOT photo) Crews drill a hole for the casing unit of a pile.
Work began this fall on a project involving the largest single contract in the history of the Delaware Department of Transportation (DelDOT). The department has been in operation for more than 90 years.
Bids were first opened for the project, which involves the new Indian River Inlet Bridge, in February 2008. The $150 million design build contract was awarded to Skanska USA Civil Southeast Inc. in August. According to DelDOT, Skanska had a combination of the lowest price, highest technical score, and fastest proposed completion time. Their project manager is Jay Erwin Jr.
Tina Shockley, DelDOT’s community relations officer, noted that funds for the project are coming from the Federal Highway Administration (80 percent) and the State of Delaware through DelDOT Transportation Trust Funds (20 percent).
Work began in September 2009, and is currently on schedule for an expected July 2011 completion.
The project is unique in that it is design-build, which allows for one contractor to design, construct, and inspect the bridge structure in one contract rather than multiple contracts. Ultimately, this saves time and money.
“It is a rare opportunity for this generation to see a cable stay bridge of this size and magnitude being built,” said Shockley. “It will be a signature bridge for the East Coast, and certainly Delaware. It is also one of the few design-build contracts DelDOT has undertaken.”
Shockley noted that having a design-build project means that the construction process is concurrent or parallel with the design process.
“While the fluidity of the design is a normal occurrence, the construction team must be ready to adapt to final design changes to keep up with the schedule,” she said. “As the construction of the bridge progresses, tracking and minimizing quantity escalation with progressing design, extreme weather conditions, and market price deviations are all challenges that the construction team will be faced with.”
According to DelDOT, the new design is both dynamic and functional. The bridge is a signature stay cable bridge with a total bridge length of 2,600 linear ft. (792.5 m) across the Indian River Inlet in the middle of Delaware Seashore State Park. It will include a 900-ft. (274.3 m) clear span over the inlet, with 1,700 ft. (518.2 m) of bridge decking over the land. All supports will be out of the water, which will eliminate conditions that are currently found with the existing bridge.
“The reason for replacing the bridge is the severe scouring that has taken place over the years,” said Dennis O’Shea, assistant director of design of DelDOT. “The Army Corps first reported evidence of significant scouring in the 1980s after an underwater survey indicated that the bridge supports, also know as piers, in the inlet were exposed and undermined.”
In 1965, there was an inlet depth of approximately 28 ft. Today, that depth is greater than 100 feet. An additional concern is the exposure of the steel H piles to salt water. DelDOT noted that they attempted to control the condition of the steel piles by installing a protection system. However, the system has been problematic, and the exposed steel support piles continue to corrode and lose strength.
“To ensure the bridge remains stable before a new bridge is built, DelDOT performs underwater diver inspections on a regular basis and the Corps has continued to provide DelDOT with their periodic bathymetric surveys,” O’Shea said. “In addition, land survey equipment on the bridge monitors movement.”
The new bridge will reportedly have a minimum 100-year design life. It is a four pylon tower suspension bridge design that incorporates cast in place concrete and epoxy-coated reinforcement steel. The foundations will be supported on 36-in. (91.4 cm) square piles.
Once complete, there will be four traffic lanes and a pedestrian walkway. The bridge will include two 12-ft. (3.6 m) wide travel lanes, a 10-ft. (3 m) wide outside shoulder, and a 4-ft. (1.2 m) wide inside shoulder in each direction. Additionally, a 12-ft. wide sidewalk will be accessed from the east side of the bridge.
A separate contract will be initiated to build new roadway approaches for the new bridge, and to permit the removal of the entire existing bridge structure down to the stream bed. The schedule for this project will coincide with the completion and opening of the new bridge structure.
New construction will include 35,000 cu. yds. (26,759 cu m) of concrete and 6,000,000 lbs. (2,721554 kg) of reinforcement steel. There will be 291 concrete pilings, each of which is approximately 110 to118 ft. (33.5 to 35.9 m) long and weigh 50 to 60 tons (45 to 54 t). The finished bridge also will include 22,700 ft. (6,919 m) of wire.
Major subcontractors include Interlock Steel Workers Inc., Md., for reinforcement steel; PB America’s Inc., N.Y., for quality control; Freyssinet, LLC, which is a French-based company with U.S. affiliates, for stay cable; and AECOM, Va., for design.
Major equipment used on the project includes two 300-ton (272 t) Manitowoc 2250 crawler cranes, two Bauer BG 24 drilling rigs, two 217,000 lbs./ft. HHK 205 Junttan hydraulic pile driving hammers, two Potain 415 tower cranes, one Junntan PM20 pile rig with a Junntan HHK 7S hydraulic hammer, one Manitowoc 3900 W crawler crane, and one Terex HC 150 crawler crane.
Originally, the Indian River Inlet Bridge project was delayed in October 2005, when DelDOT decided not to accept bids for the signature arch bridge as scheduled. At that time, only one bidder expressed interest, and the bid was higher than DelDOT was willing to accept.
Delaware Seashore State Park is operated and maintained by the Delaware Department of Natural Resources (DNREC). DelDOT noted that since it encompasses both the north and south sides of the Indian River Inlet, the proposed realignment of the bridge and roadway approaches have required substantial coordination between DelDOT, the DNREC Division of Parks and Recreation, the local community, and several other groups and agencies. As a result, several park enhancements have been proposed. They will include day-use facility improvements, campsite improvements, new and enhanced bathhouses, a park office, contact stations, additional recreation areas, new lighting and landscaping, handicap access to the new bridge, and marina improvements. CEG