Reconstruction of what is known as the “Stretch” of U.S. 1 between Key Largo and Florida City began in April 2005 under the direction of the Florida Department of Transportation (FDOT), District Six. Once known as the Overseas Highway, U.S. 1 spans 127.5 mi. (205 km) through the Keys.
The two-lane highway has a long history of safety concerns due to speed and traffic volume, with a higher than usual number of crashes, including head-on collisions and vehicles running off the road. The roadway is being reconstructed to include one travel lane in each direction divided by a concrete median barrier wall to prevent future head-on collisions.
Another key reason for the project is to improve hurricane evacuation. As the only route out of the Keys, the completed roadway will be equipped with a 10-foot-wide northbound shoulder that can be used for hurricane evacuations when necessary. This allows for two lanes of traffic to travel north during emergencies.
Florida Folly
U.S. 1 is a major north-south U.S. highway along the country’s east coast. From Key West, it runs more than 2,000 mi. (3,218 km) north to Fort Kent, Maine, on the Canadian border. Along the way, it connects many important cities, including Miami; Raleigh, N.C.; Richmond, Va.; Washington; Philadelphia; New York City; Boston; and Portland, Maine.
Much of the portion in the Keys was built on the former right-of-way of the Overseas Railroad, part of the Key West Extension of the Florida East Coast Railway. The Railroad, completed in 1912, was heavily damaged by the Labor Day Hurricane of 1935 that took the lives of 800 people, including 200 WWI veterans who were building bridges for the new highway as part of a government relief program. Extensive damage was sustained in the Middle Keys after the Category 5 hurricane — then considered “the storm of the century” — blew through.
Dubbed “Flagler’s Folly” during construction, in honor of its builder, Henry Flagler, the Florida East Coast Railway introduced several engineering innovations and required extensive amounts of labor and funding. At one point during construction, 4,000 men worked on the project. Three hurricanes slowed work during its seven-year construction, but it was finally completed in 1912 for $50 million. Bankrupt and financially unable to rebuild damaged and destroyed sections after the 1935 hurricane, the Florida East Coast Railway sold the roadbed and remaining bridges to the State of Florida for $640,000.
Many of the remaining railway bridges and other infrastructure were incorporated in construction of the Overseas Highway. The roadway was built on top of old truss bridges in some locations. In the 1980s, several of the original bridges were replaced and the entire roadway was rebuilt, but some of the bridges, now listed on the National Register of Historic Places, have been left for use as fishing piers.
Extensive Reconstruction
FDOT spokesperson Abbie Kelley, with Parsons Brinckerhoff Inc., explains that the project includes the reconstruction of the existing two-lane roadway north of Jewfish Creek with a median barrier wall and a new 1.5-mi.-long (2.4 km) high-level bridge over Jewfish Creek that extends as a low-level bridge/causeway over Lake Surprise that will replace the existing 1944-era Jewfish Creek bascule bridge. The portion of bridge over the Atlantic Intercoastal Waterway stretches 160 ft. (48.7 m) over the waterway and is elevated to provide a 65-ft. (19.8 m) vertical clearance for navigation. As a fixed bridge, it will no longer delay motorists traveling on U.S. 1 due to the raising and lowering of the drawbridge for watercraft, which so often caused traffic backups during heavy traffic flow.
The reconstructed section of the roadway will feature two 12-ft. (3.8 m) travel lanes, a 10-ft. (3 m) northbound shoulder that can be converted to a travel lane during hurricane evacuations and an 8-ft. (2.4 m) southbound shoulder. The existing roadway will be widened for five mi. (8 km) north of the bridge and two mi. (3.2 km) south of it.
Construction also includes two new fixed-span bridges over Manatee Creek and Crocodile Creek and the installation of nine 6 by 10 ft. (1.8 by 3 m) wildlife box culvert crossings and associated wildlife fencing. This two-lane safety project includes a number of environmental enhancements designed to improve safety on the corridor.
Keys to Environmental Concerns
Not a simple dredging and filling job like the original railway construction in the early 20th century when environmental issues in the delicate Florida Keys weren’t a concern, current reconstruction makes preserving the ecosystem and various life forms inhabiting the region a top priority.
“This particular stretch of U.S. 1 traverses an environmentally sensitive area,” Kelley indicates. “The Florida Department of Transportation has been committed to maintaining the environmental integrity of the project area. Great attention has been focused on the unique natural character of the area.”
The Florida Keys are actually the exposed portions of an ancient coral reef, with some small transitional keys and barrier islands built up of sand around areas of exposed reef. The Upper Keys are remnants of large coral reefs that fossilized as the sea level lowered, exposing them. The Lower Keys are composed of accumulations of limestone and sand produced by plants and marine organisms.
“Addressing environmental permit requirements has been the most challenging aspect of the project,” Kelley reports. “The main concerns fall into two broad categories; environmental protection during construction and maximizing long-term enhancements.” The project is located in a particularly sensitive region, located in or adjacent to a National Park, National Marine Sanctuary, Federal Crocodile Refuge and within an area designated as Outstanding Florida Waters.
To address environmental concerns, numerous environmental and hydrological enhancements have been incorporated into the project, such as the installation of storm water run-off treatment/retention facilities, a restoration program to help restore original flows in the Everglades, wetland mitigation including sea grass, mangrove and freshwater emergent habitat restoration, and the construction of wildlife crossings and box culverts throughout the corridor, with fencing to direct endangered panthers, crocodiles, manatees and other wildlife to the crossings.
“Long-term environmental enhancements were designed into the project from the beginning,” Kelley notes. Culverts were located in areas to allow historic surface water flow as part of the larger comprehensive Everglades Restoration Program designed to help restore original flows in the Everglades and throughout the Keys. Additionally, Kelley explains that near Key Largo, a causeway originally built for Flagler’s railroad has been removed to restore flow across a saltwater lake, a critical habitat for Manatees. “These culverts also serve as crossing points for the endangered Florida panther and American crocodile, alligators and other wildlife.”
Because the job borders the Everglades National Park, special care was taken to protect wildlife in the area. Granite Construction of Tampa, a unit of the Watsonville, Calif.-based contractor, took additional steps to avoid disturbing resident fauna. Michael Derkson, project manager with Granite, told Southeast Construction, “Environmental issues are a major concern. We’ve had to take a proactive approach.” Part of that approach involved educating its workforce about how to deal with manatees, sea turtles, dolphins, osprey, crocodiles, snakes and other wildlife they might come into contact with.
Due to the narrow footprint permitted on this project and the sensitivity of the surrounding area, Kelley elaborates, construction activities have been closely monitored. Daily inspections on environmental controls are conducted. Periodic reviews of all environmental permits are also conducted to ensure compliance.
In addition to protecting the many species of aquatic life, crews were careful to remain within clearing limits and not to disturb indigenous and endangered mangroves. Storm water runoff treatment/retention facilities have been added throughout the project to protect adjacent water bodies. The new roadway and bridge rise higher over the channel and the bridge can stay open during dangerous storms, unlike the previous bascule bridge. Also, leftover excess material from the project was used to restore several acres of sensitive habitat at the nearby Florida Department of Environmental Protection and Crocodile Lake National Wildlife Refuge properties.
In the Works
FDOT reportedly had plans in the works for almost two decades — plans that ranged from two-lane enhancements to three-lane and four-lane designs. Finally let for bids in 2004 as a design-build project, final plans included a two-lane replacement bridge over Jewfish Creek. Granite Construction, experienced in both bridge and roadwork, was awarded the $147.8 million contract that year, with a January 2005 start date.
The state-funded project had run up a tab of $156.4 million by June 2009, according to Kelley, and has the potential for additional incentive money to be paid out if project deadlines are met. The first bonus date was extended due to hurricane impacts during the course of construction. The milestone bonus for $2 million was for completion of the roadway. The second bonus for $2.4 million is for final completion.
At times during the project, there were up to 150 workers onsite daily. Kelley said Granite used cranes with the capacity to construct a large proportion of the bridge from the existing causeway, minimizing the need for barge-mounted cranes
Despite the manpower and heavy machinery onsite, meeting deadlines has sometimes been a challenge, due to weather and soil conditions. As Kelley points out, the current northbound roadway was built on top of a very soft and highly compressible soil, consisting of a mixture of silt, clay and plant matter that geotechnical highway engineers commonly call organic silt and fibrous peat or muck. “The soil stabilization process that was performed prior to our road construction has no American precedent.” Although the process has been used in Europe, Kelley believes it is “the first time in the history of United States construction that this innovative dry mixing method was used.”
Instead of demucking, hauling muck offsite and backfilling with good fill material, Kelley said, Granite teamed with Hayward Baker, a geotechnical contractor based in Odenton, Md., in adopting a relatively new Swedish technology called soil mixing. The process permits road building on top of the existing muck, allowing crews to widen the roadbed north of Jewfish Bridge using the organic soils rather than have to haul out the soil.
Using a rototiller-like device on a backhoe boom, the contractor injected the in-place muck material with a mixture of 25 percent cement and 75 percent slag, building a 10-ft. (3 m) solid base foundation that anchors the current roadbed to the unyielding caprock below. “In other words,” Kelley explains, “soil mixing is a means of hardening soft soils in place without the necessity for their removal.”
Southeast Construction reports that The Cemex Card Sound Mine in Florida City, Fla., supplied the lime rock for the roadbed and the ready mix for the bridge. Granite milled the old asphalt and blended it with new to reconstruct the existing lanes. Six ft. (1.8 m) of fill was placed on top of the mixture.
Another important advantage of soil mixing over the removal and replacement method of soil stabilization on the project is that soil mixing did not require large fleets of heavy dump trucks traveling back and forth along U.S. 1, which thus minimized impacts to the traveling public and the environment.
Jewfish Creek Bridge
An important aspect of the project involved replacing the low drawbridge over Jewfish Creek in Key Largo with a high-level concrete and steel bridge that has 65-ft. (19.8 m) clearance, eliminating the need to stop traffic for bridge openings to permit marine traffic to pass. The former bridge had to be locked down during storms, delaying traffic exiting the Keys.
The outdated 300-ft. (91.4 m) drawbridge — as well as some of the fill placed by Flagler’s crews nearly a century ago — was replaced by a 7,500-ft. (2,286 m) bridge featuring one travel lane in each direction (plus shoulders), divided by a concrete median barrier to prevent head-on collisions. Four ramps provide access to local businesses. Beams for the ramps were set with the help of a long hydraulic crane perched on the finished bridge. Work was completed in May.
In accord with FDOT’s mandate to minimize environmental impact, crews were granted restricted access while constructing the bridge. They drilled more than 260 48-in. (121 cm) and 60-in. (152 cm) shafts and erected 69 piers for the bridge foundation from floating platforms.
Granite excavated the area, removing the old causeway. This opened up the saltwater lake, improving water quality and enhancing the crocodile and manatee habitat. Nine box culverts were built north of the bridge to allow crocodiles to pass under the roadway. Water quality berms were added for storm water treatment and the elimination of the land causeway section over Lake Surprise helped restore natural water flow. “This minimized the impact to the sea grasses of Lake Surprise by reducing barge traffic, tug boat wash, etc.,” Kelley adds.
Wildlife wasn’t the only thing FDOT didn’t want disturbed. In order to minimize disruption to traffic, a crane set up on a trestle bridge perpendicular to the roadway set 450 beams at night. Standard Concrete Products of Tampa cast the 92 78-in. (198 cm) Florida modified Bulb-T beams, the 343 72-in. (182 cm) Florida modified Bulb-T beams and the 29 AASHTO type IV pre-stressed beams, reports Southeast Construction. Some, including the 160-ft.-long (48.7 m) center span, had to be shipped by barge from Tampa.
Demolition of the old bascule bridge has commenced. Removal of its two foundations from the creek has allowed water to flow and begin restoring the shoreline. CEG
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