Jensen Causeway Project Eliminates Drawbridge

Thu November 27, 2003 - Southeast Edition
Cynthia W. Wright

Offering the charm of “old-time” Florida, Jensen Beach is an important tourist destination of Martin County.  But as time passes and visitors come and go, some of the most notable landmarks on the beach need to be rebuilt and even replaced.

This is the case with a drawbridge that connects the mainland and Hutchinson Island and makes up part of the Jensen Beach Causeway. Crews are constructing a $31.7 million two-lane bridge that is expected to last for the next 75 years –– 55 years longer than the usual 20-year projection.

There are a variety of reasons for building the new 2,523-ft. (769 m) Frank A. Wacha Bridge.  The first is capacity.  With a growing influx of people moving to the state, local population numbers are soaring. Secondly, the existing bridge doesn’t have the updated safety rails or shoulders and is considered to be structurally deficient.  Finally, the annual cost of operating the drawbridge is approximately $300,000.   With a 65-ft. (19.8 m) vertical clearance, the new bridge will eliminate the need for a drawbridge, cutting costs.

Building in Shallow Waters

Surrounded by sea grasses and other marine lifeforms that breed in the shallow waters, the project is very environmentally sensitive, said George Denti, Florida Department of Transportation (FDOT) project manager. “[The bridge] was designed using temporary work platforms –– trestles –– to be built to allow for construction without barges, due to prop dredging potential.  We designed the bridge around temporary trestles adjacent to the new structures.

“[The project] is actually a series of three bridges including the Frank Wacha, creating a challenge,” Denti said.  “Right now we’re dealing with two flat relief bridges and the main structure.  Just a slue type of bridge.”

When it came to the east relief bridge, which is approximately 600 ft. (182.9 m) long, FDOT found significant utility interferences with submarine cables that ran in the area of the proposed trestles. 

“No accurate locates could be made.  No realistic relocations could be accomplished,” said Denti. “As a result, we were unable to install the trestle foundations.  We had to come up with an innovative way to construct the bridges, and still maintain traffic while staying out of the water.  We came up with a top down method.” 

Crews moved cranes onto the shore and drove a set of pilings into the ground. They then put a temporary steel frame around the pilings, walked the crane up on it and just kept moving forward with driving pile, Denti explained. “Behind us, we poured cap and deck.”

FDOT is building the new bridge on top of the new foundation, using it to support the equipment.  “In essence, some work is ahead of us, some work is behind us,” Denti noted. “Two important advantages:  no negative environmental impact and no utility interferences.”

Currently, crews are setting beams and pouring cast in place. “ The number of workers ranges from 50 to 100 at any given time, working five days a week, occasionally six,” said Randall Scott, project engineer, explaining that the substructure is complete. 

“The girders we’re putting on are some of the longest and heaviest that FDOT has erected,” Scott noted. “At 161 feet long from pier to pier and weighing 93 tons, the new Frank A. Wacha Bridge center span will hold the world’s record for the longest Florida Bulb Tee pre-stressed beam.” 

The new bridge is expected to eliminate backups due to openings and burned-out circuits or broken locks.

In total, 1,228 tons (1114 t) of reinforcing steel will be used in the bridge, more than 57,000 ft. (17,400 m) of piling and more than 54,000 cu. yds. (41,300 cu m) of fill.

The prime contractor is Archer Western, a subsidiary of the Walsh Group of Chicago. Robert Novynka is the project manager. Equipment is both owned and leased.

The project also includes the construction of a roundabout (rotary circle) at Jensen Beach Boulevard and A1A, eliminating the present traffic light.  New seawalls to protect the recreation islands from future erosion, picnic pavilions, a fishing pier under the main bridge, a new boat ramp with three docks, four scenic overlooks with benches and decorative street lights are among other amenities. 

Reconstruction of the bridge fender will widen the Intracoastal Waterway Channel by an additional 40 ft. (12 m).

The level of service the new bridge will provide will remain at “C” according to the engineers’ traffic grade measurement system of A to F, meaning the bridge should be sufficient for decades. 

The bridge is expected to be completed in January 2005.