Construction crews in downtown Milwaukee, WI, implemented an innovative slide rail system to overcome congestion challenges and complete the $3.8 million installation of a new storm-sewer system in September 2005.
The project was a relatively small, but nonetheless vital, aspect of the North Leg phase of a massive $810 million overhaul of the Marquette Interchange, considered the state’s most critical transportation link to the rest of the country by the Wisconsin Department of Transportation (WDOT).
Walsh Construction Company is the primary contractor working on bridge rehabilitation and construction in the North Leg, I-43 construction phase, which began in October 2004 and will wrap-up in December 2006.
The Milwaukee-based company sub-contracted the storm-sewer installation project to Ricci/Welch Inc. of Rolling Meadows, IL.
The new pipeline, running south along south-bound I-235 near W. Fond Du Lac Avenue, was challenging to install because of all the bridge and road work along the adjacent highway.
Project Superintendent Anthony Welch had to stop progress on the pipeline twice to allow other construction in and around the storm-sewer to move out of the way.
This congestion, coupled with the limited space in which it was working, completely eliminated the option of sloping the pipeline’s trench.
Welch needed a different shoring option and contacted Tim Ryan, a sales representative of Fabco Rents, a distributor of trench safety equipment in Wisconsin, for help.
“After consulting with Anthony, I knew right away that a Slide Rail system would be an ideal shoring option when working in such a congested area,” Ryan explained. “Slide Rail is installed at the same time the trench is excavated and requires no sloping. The trench walls remain completely vertical and the cut only needs to be a few feet wider then the pipe’s outside diameter.”
Manufactured by Safe-T-Shore of Chandler, AZ, Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts.
Slide Rail is installed simultaneously as the trench or pit is excavated by sliding the panels into integrated rails on the posts (either two or three rails depending on needed depth), then pushing the panels and posts incrementally down to grade as the pit is dug; a process commonly referred to as a “dig and push” system.
The versatile system can be used in a variety of configurations, such as a four-sided pit or linear multi-bay application.
In a linear multi-bay configuration, which the contractor utilized, spreader pipes are pinned in place to a set of parallel beams with rollers that slid down slotted rails on the inside of two linear posts, providing the cross-trench support.
Ricci/Welch Inc. rented a six-bay linear application Slide Rail system from Fabco Rents. The bays were 14 ft. (4.3 m) long, and the linear posts 24 ft. (7.3) tall. They used 6 ft. (1.8 m) spreader pipes pinned-in-place to the set of 1 ft. (.3 m) wide parallel beams resulting in a total trench width of 8 ft. (2.4 m) to accommodate the 42 in. (106.7 cm) concrete pipe and pre-cast manhole structures.
Slide Rail is installed and removed incrementally, which allows the trench to be properly shored throughout the entire installation or removal process and protect workers from a trench wall collapse.
“The system did work well, and I can see many uses for it in the right situations and ground conditions,” Welch said. “The ground on this job was harder than what we expected, however we moved along fairly quickly after using the system for a while.”
The job started in August 2005, and was completed on time Sept. 17, 2005.
Originally completed in 1968 at a cost of approximately $33 million, the Marquette interchange carried 300,000 vehicles per day by the early 2000’s, according to the WDOT, and connects one-third of the state’s freeway traffic to the rest of the country. The four-year reconstruction project is scheduled for completion in 2008.
Ricci/Welch Inc. used the following equipment on the job:
• A Komatsu 400 excavator for digging, setting the slide rail and laying the pipe;
• A Caterpillar 345 excavator for removing the slide rail system; and
• A Caterpillar 963 front-end loader for backfilling.
Ricci/Welch Inc. specializes in heavy highway underground work. Started in 1988, they are a member of the Underground Contractors Association of Illinois, the Illinois Road and Transportation Builders Association, and Excavators, Inc.
Fabco Rents provides a complete line of shoring and trench shielding equipment available through its 12 Wisconsin locations.
Fabco Rents provides steel and aluminum trench shields; steel manhole boxes; Safe-T-Shore’s Modular Design-A-Shield Aluminum Trench Shielding System; hydraulic vertical shores, walers, and hydraulic aluminum shields; as well as Slide Rail Systems from Safe-T-Shore.