The Bruce SGH-3013 successfully completed the pile driving of Hathaway Bridges at Fl, USA
By Florida State University College of Engineering, Fall Semester 2008
A Thesis submitted to the Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the degree of Master of Science and The Office of Graduates Studies has verified and approved.
History of Hathaway Bridge
The First Hathaway Bridge was built in 1929 and was originally known as the St. Andrews Bay Bridge.
It was later renamed The Hathaway Bridge after Franz Hathaway,whowas Chairman of Florida’s State Road Department, the predecessor to the Florida Department of Transportation (FDOT).
For its time the St. Andrews Bridge was a remarkable achievement in engineering. It utilized 16 Parker through-truss spans that were 160 to 225 feet in length and 31 to 38 feet high with a 20 foot-wide roadway.
To 14 accommodate shipping traffic the bridge encompassed a 200 foot long Warren through truss “swing span” that would open and close as needed. (Bridgepros)
By the mid 1950’s the Bridge was becoming functionally obsolete and structurally deficient.
So in 1960 the second Hathaway Bridge was opened to the public, this new bridge was more than three times wider than the original with double the number of lanes on a 62 foot wide roadway, four 13-foot lanes with two in each direction of traffic.
However, like many other bridges built in the 1950’s the Hathaway II Bridge as its affectionately known was built with a sense of practicality and economy.
It was a utilitarian structure with three foot outside shoulders, a four foot raised center median,no pedestrian access, no dedicated bicycle access, and no “refuge lane” for broken down vehicles.
A small accident or a stalled vehicle could create huge traffic snarls and bring traffic to a standstill. (Bridgepros)
With the population boom in Florida after 1960 the Hathaway II would become obsolete by the 1980’s. In 1970, an average 15,600 vehicles were crossing the bridge 15 each day.
The number doubled by 1982 and approached 57,000 by 1998 By the late 1990’s after many failed efforts to alleviate the traffic with trolleys and ferry boats, Panama City wanted to attach a bicycle and pedestrian structure to the bridge but when the price tag jumped $3 million to $8 million dollars the idea was dropped.
So in 1997 the Bay County Bridge Authority, the Panama City Metropolitan Planning Organization and the Bay County Tourist Development Council all voted to support the construction of a new bridge.
In 1999 the third Hathaway Bridge came to life as theFlorida State Legislature appropriated over $80 million dollars for the construction of the new bridge.
By 2020 an estimated 97,700 vehicles will be using the bridge daily.(Bridgepros)
The New Bridges
The new Hathaway Bridge consists of twin, 80-ft-wide segmental concrete box girders.
These precast, single-cell bridges have haunchedmain spans of 330 ft with shorter (approximately 200-ft), constant-depth approach spans.
The new bridge is actually two bridges, which will both carry three lanes of traffic, one auxiliary lane and one pedestrian/bicycle lane in a single direction. The new bridges will be built just north of the existing bridge and within existing state right-of-way.
No additional property was required for the new bridges, and environmental impacts would be minimal.
• Two separate bridges, each consisting of an 80-foot wide bridge deck
• Four 12-foot wide lanes of traffic in each direction
• 10-foot inside and outside shoulders
• 8-foot lane for pedestrian/bicycle traffic on the outer edge, separated from traffic by a concrete “Jersey style” barrier
• One lane in each direction to be used as a auxiliary lane, providing a “refuge lane” for disabled vehicles
• Total Bridge Length: approximately 3800 feet
• Vertical Navigational Clearance: 65 feet (meets minimum navigational height for the IntercoastalWaterway)
The first step the preliminary design team had to develop was the alignment and profile of the bridge. This was developed electronically within an electronic right-of-way limit provided by the design surveyor.
This alignment and profile was then usedto lay the bridge out and achieve required vertical clearances.
Early on when the design team decided that both bridges would beput on the north side of the existing bridge they knew that they would have tight control requirements.
Once the Granite reamrealized they would be very close to the project right-of-way limit they hired DRMP, who had performed the original survey for the FDOT to confirm that they were in fact within the ROW limits. And in fact they were.
Given the nature of the Design/Build approach, the Granite team had freedom with the design that allowed for much flexibility.
They poured over numerous options that included asking the coast guard if they could use a shorter channel span, and also contemplated constructing just one combined bridge.
Once the alignment had been finalized they had a clearly defined design process that would require the development of geotechnical and scour assumptions that were used to design a preliminary foundation system for the bridge that could be quantified.
Simultaneously, superstructure designs using different span lengths were developed so they too could be quantified.
To find the best combination of superstructure and substructure design both elements were looked at iteratively.
The solutions the design team came up with were then sent to the construction side of the team for input and modification.
This phase of the Design/Build process is why many believe it has huge advantages over the traditional design-bid-build methodology.
As this is when there can be a free flowing exchange of ideas about the planning and design between both those on the construction side as well as the design.