Location: Between Bristol & Blountstown, Florida Designed by:  FDOT Central Structures Design Office CEI:  Parsons Brinckerhoff Construction Services Inc. Prime Contractor:  Odebrecht Contractors of Florida, Inc.

Looking East over Apalachicola River from West Approach. Old SR20 Bridge on the Left.

Project Name: The New State Road 20 Bridge over the Apalachicola River.

Location: Between Bristol (Liberty Co.) & Blountstown (Calhoun Co.) Florida (District 3)

Bridge Statistics:

• Length: 8362 feet
• 3 Main Spans 225', 280', and 225' (Steel Plate Girders)
• Typical Approach Span Length 110' (72" Prestressed Concrete Bulb Tee Girders)

The new SR 20 Bridge between Bristol and Blountstown in the Florida panhandle crosses the Apalachicola River, a major state waterway, and its wide, wooded floodplain. The new bridge is 8362' long and when completed will carry two lanes of east bound traffic. The new bridge is on an alignment parallel to the existing historic Blountstown Bridge which was built in the late 1930's. The existing bridge will be rehabilitated as part of this project and when completed will carry two lanes of west bound traffic. Odebrecht Contractors of Florida was the low bidder on the project at $27 million.

Trestle Bent Cap form work.

First prestressed beam being delivered to west end of bridge.

The superstructure of the new bridge is a combination of steel and concrete girders both supporting a conventional reinforced concrete deck. The river crossing is accomplished using a variable depth three span continuous steel plate girder with 225', 280' and 225' spans. The long approaches over the floodplain consist of 72" deep simple span prestressed concrete bulb-tee girders. The approach spans are 110' long typically with several 87' and 99' spans at each end to match the length of the existing bridge. Galvanized steel stay in place deck forms were utilized to support the casting of the deck. The prestressed concrete bulb-tee girders were cast in nearby Blountstown. The steel girders were fabricated in Montgomery, Alabama. Both the steel and concrete girders were trucked to the bridge site.

The substructure of the new bridge consists of two different foundation types. The low level western approach spans are supported on pile bents consisting of 30" square prestressed concrete piles driven plumb with cast in place reinforced concrete caps. The high level approaches and steel plate girder river unit are supported by cast in place reinforced concrete piers founded on 5', 6', 7' and 9' diameter drilled shafts. The 9' diameter drilled shafts, the largest ever used on an FDOT bridge, support the two piers in the river. An extensive geotechnical load test program was part of this project. A lateral load test will be performed on a 9' diameter shaft. Axial load tests were performed on each different size of shaft using 3000 ton Osterberg cells or Statnamic testing. The axial load test on a 9' diameter drilled shaft set a world record of 15,000 (fifteen thousand) tons. Cross-hole sonic logging and SID (the Shaft Inspection Device, a video camera inspection device) were used to monitor the construction quality of the drilled shafts.

Shaft Inspection Device (SID)  Rebar cage for 9' Shaft being placed.

Lifting back span girder.

The new bridge accommodates a 150' wide navigation channel with a vertical clearance of 55' over the river. A sidewalk is provided on the new bridge to allow hikers on the Florida Trail to easily cross the Apalachicola River. The reverse curvature of the new bridge alignment creates a pleasing "S" shape when viewed from the lower existing bridge.

Special thanks to Marcus Kelly of Parsons Brinckerhoff for Photos and Site tours.

Looking West showing 9' Diameter Shafts with Columns	Osterberg cells for testing of 9' Diameter Shafts.
Gabion Mats being placed in channel for erosion protection.	225' Back Span.
River view looking west.	Placing main span girders.
Mid-air splice over river channel	Eastern bridge approach.
Rebar cage for 9' Diameter Shaft.	Rebar cage for 9' diameter shaft.
The old and new main spans looking east.	The new and old western approaches looking west.