Dive Brief:

• The $2.7 billion, 170-mile Brightline high-speed rail extension from West Palm Beach, Florida, to Orlando International Airport (OIA) will see the construction of a train tunnel in two weeks instead of almost one year thanks to an innovative box-jack system suggested by general contractor Granite Construction. This is the first time the box-jack system will be used for a train project outside of the Northeast United States.
• The developer of the box-jacking system, Italian company Petrucco, is using special hydraulic jacks to push two precast concrete boxes — one 146 feet long and the other 126 feet long and both with 42-foot-long sidewalls — under a roadway east of the airport while an excavator digs out a path from inside the box and from the opposite side. Each box weighs more than 3,000 tons, and the installation will take a 40-person crew working 12-hour shifts around the clock. 
• Rail officials also plan on using the box-jack system next year to create a second train tunnel underpass along the South Florida-to-OIA route in Cocoa, Florida, avoiding shutting down traffic for almost a year in that location as well. 

Dive Insight:

Commonly used in Europe for rail construction, the box-jacking method was first used in the U.S. earlier this year on the Long Island Railroad expansion project in New York City. In this project, similar precast concrete boxes were installed under roadways eliminating the need for at-grade railroad crossings. 

Richard Brown, project manager for Granite, which cast the boxes on site, told Construction Dive that traditional tunneling wasn’t an option on the Florida project because of the existing grades of the roadway and the proposed track grades. In addition, conventional construction methods would have created an approximately 10-month detour for motorists, Brown said, as opposed to the two-week detour that is now planned.

Beyond the Brightline project, Brown said Granite will look at box-jacking on future jobs.

Granite's $557 million portion of the project is the 37-mile, Zone 3 section that runs from Cocoa to OIA, according to Brightline spokesperson Katie Mitzner. Other contractors on the job include:

• Hubbard Construction and Wharton-Smith Inc., which will perform site preparation and building on about 70 acres south of OIA, are the contracting team for Zone 1.
• The Middlesex Corporation will handle site and infrastructure work in Zone 2, which stretches 3 miles through the airport. 
• HSR Contractors, a joint venture between Herzog, Stacy & Witbeck and RailWorks, will upgrade approximately 130 miles of existing track in Zone 4. This improvement from Class IV to Class V track will allow trains to travel up to 110 miles per hour.

Last month, Mitzner told Construction Dive that more than 750 workers are currently manning the expansion and that the company expects to add more in the months ahead. 

Work on the expansion's bridges and 155 at-grade crossings is also underway. At the airport, contractors have laid rail and have broken ground on a 109,000-square-foot vehicle maintenance facility.