City officials of Clearwater, Florida, envisioned an architecturally significant structure to replace an ailing bascule bridge when they first considered the Memorial Causeway Bridge several years ago. Built in the early 1960s, the original bridge was notorious for getting stuck in the raised position and blocking traffic on the main downtown roadway. The leaders of this tourist-driven community decided that they could not wait until the end of this decade for the bridge to be replaced as Florida Department of Transportation had planned and, instead of a lower cost AASHTO girder bridge, they wanted a signature structure that would leave a lasting impression on the tourists who cross the bridge to get to Clearwater Beach, the city’s main attraction.

To achieve these two goals, the city struck a deal with FDOT — the city would find the money to acquire the necessary right of way and provide the design for the bridge, and FDOT would procure and manage construction. City officials tapped several sources to acquire the funding, including city, county, state and federal funds, and they hired an architect to work with the bridge designer and produce landmark design for the city’s gateway to the beach.

After several years of planning and design, the city presented FDOT with a design for a cast-in-place segmental concrete bridge. It consisted of a twin box girder section 34 m (112 feet) wide and depths varying from 2.7 m (9 feet) in the center spans to 5.4 m (18 feet) at the pier tables. The bridge was 690 m (2,300 feet) long and had nine spans. The main span was 108 m (360 feet) long with a 22-m (74-foot) clearance over the channel at high tide.

Under a joint project agreement, the city deposited its funds with FDOT. The FDOT’s portion of the agreement was to hire a consultant to perform construction engineering and inspection and a construction firm to build the bridge. In May 2001, FDOT selected PBCS as the CEI and in September 2001 put the project out for bid. Much to the city’s surprise, all of the bids came in above the engineer’s estimate. There was much speculation about the contract time given for the project — 800 days — and its effect on the bid prices, which ranged from $47.7 million to $61.0 million.

Initially, city officials were doubtful that the project would be built. They had agreed to put up a contingency amount equal to 10 percent of the bid price, but when the bids came in over the engineer’s estimate, the city did not have the required funding. After a series of City Commission workshops, however, additional funding by FDOT, and indications from the low bidder that there were value engineering savings to be had, the City and FDOT agreed to award the construction contract to PCL Civil Constructors in late November 2001.

As soon as the construction contract was executed in early December, PB, FDOT, the City of Clearwater and PCL had the first round of meetings during which PCL presented a value engineering package that ultimately preserved the aesthetics the City had worked so hard for while reducing the costs by $1.34 million. To PCL’s relief, the agreement also included a 60-day delay to the construction start date and a contract time extension of 60 days. The agreement called for FDOT and PCL to share the savings equally.

The Value Engineering Proposal

PCL’s value engineering proposal called for changes to the substructure and superstructure of the bridge. In fact, the changes were so significant that PCL’s designer became the engineer of record under the agreement.
Substructure Changes. In the substructure, the drilled shafts were changed from 1.5-m (5-foot) diameter to 2-m (6.5-foot) diameter shafts. The original design was bound by guidelines that limited the size of the drilled shafts to ensure competition among the bidders, but now PCL was not bound by the same requirement and was able to capitalize on the abilities of a qualified drilled shaft subcontractor.

As a result of this change, the total number of drilled shafts was reduced from 88 to 24, leading to significant time and cost savings. In turn, the footing sizes were reduced from over 765 m3 to 500 m3 (1,000 cubic yards to 650 cubic yards). Lastly, the shape of the columns was changed very slightly to maintain consistency, allowing the same forms to be used on all of the columns. The total savings for the substructure changes was approximately $577,000.

Superstructure Changes. In the superstructure, the changes were more discrete but no less significant:

• To accommodate the tight construction schedule, the erection method was changed from balanced cantilever construction on each span to a combination of balanced cantilever and construction on falsework. This change allowed the schedule to be met with two pairs of form travelers.
• The overhang portions of the bridge decks were shifted to create a symmetrical box, allowing for a more economical form system.
• The amount of post tensioning was increased and the thickness of the web walls was decreased, resulting is a lighter section, that in turn, reduced the cost of the form traveler and of material.
• The bearings at four of the columns were replaced by Freyssinet hinges at two of the columns and fixed integral connections at the other two.

The total savings from the superstructure changes was approximately $750,000.

Lessons Learned

The purpose for delaying the construction start date was to allow the value engineering design to be completed and reviewed first. We quickly found that the time frames proposed by the contractor for design production were not reasonable. As a result, construction began without a complete set of approved plans and the engineering has been chasing the construction all the way. Without the approved design plans, the construction engineering (the contractor chose a different consultant than the new Engineer of Record), was constantly driving the construction schedule. On more than one occasion, the construction could not proceed because the contractor was waiting for a shop drawing to be produced or approved. In addition, the tight schedule probably resulted in more errors in the shop drawings than would have occurred otherwise.

We also believe, however, that the project would not have gone forward without the value engineering proposal. The additional work and effort by everyone involved in the production, review and implementation of the value engineering change proposal was a good trade.

One of the most overlooked advantages of the value engineering proposal is that the owner was able to transfer design problem risk to the contractor and limit costs for design problems to the roadway portion of the project only. On a project with very little funding for overruns, this was a significant achievement. For future segmental projects though, planners should give serious consideration to the design/build concept. Our experience with the value engineering proposal shows that most of the savings came from changes that were suited specifically to PCL. Under a design-build concept, the owner may have enjoyed even greater savings.