Cover Story — May/June 2005

DIGGING IT

Trenching Across the 'Biggest Little City' in the World

By Tony Illia

The mammoth channel will use 10,000 truck loads of concrete and require 661,000 cu yds of excavation, 140,000 cu yds of backfill and 9 million lbs of reinforcing steel. Roughly 80,000 cu yds of concrete will form the 2.5-ft-thick, U-shaped trench. PHOTO COURTESY OF DAVID ROBERT

Reno gets a new railway trench that will ease congestion, improve aesthetics and increase access through its busy downtown corridor.

Reno, known for its glittering casinos, headliner celebrities and lively nightlife, is removing an unsightly blemish from its downtown landscape by building a depressed rail trench similar to the Alameda Transportation Corridor near Los Angeles.

The $265.4-million design-build project, called ReTRAC (Reno Transportation Rail Access Corridor), will neatly tuck away heavy train traffic that has run at-grade for decades through the heart of the city, making the area more tourist friendly.

The 42-month ReTRAC project will alleviate traffic congestion, improve visitor safety and boost property values by creating a 33-ft-deep, 54-ft-wide rail trench along the existing Union Pacific railroad tracks. The 2.21-mile-long job runs from the intersections of Fourth and Second streets, east to Sutro Street and Commercial Row. It consists of two mainline tracks that can handle train speeds up to 60 mph, with 11 at-grade bridge crossings above for vehicle traffic and an access road.

The city hired the Truckee Meadows ReTRAC Team, a joint-venture between Moffatt & Nichol Engineers, Long Beach, Calif., and DMJM+Harris, a New York City-based Aecom subsidiary, in June 2001 to facilitate the design-build procurement process. The team developed bridging documents from 20 to 30% completion, outlining the trench depth, alignment, width and other performance/ design criteria. The city later hired Jacobs Engineering Group Inc., Pasadena, Calif., as project manager under an $8.8-million contract.

Truckee Meadows ReTRAC Team, the joint-venture contractor on the project, is installing a waterproof cutoff wall and seal slab across the trench bottom, consisting of 30,000 cu yds of tremied concrete and eight miles of foundation piles. PHOTOS COURTESY OF DAVID ROBERT

"Very early on it was our judgment that design-build would be the best procurement method," says Steve Varela, city public works director. "We saved about 18 months over a traditional design-bid-build method. Due to the number of different construction concepts and possibilities, we didn't want to restrict the contractor."

The city launched a two-step design-build competition in the late 2001, evaluating the eight teams' experience, financial strength and backgrounds. The field was then narrowed down to four teams that detailed costs, design, schedule and construction. The winner was ultimately selected on a best-value basis, where price accounted for 70% of the decision.

Granite Construction Co. Inc., Watsonville, Calif., with Parsons Transportation Group, Pasadena, Calif., was awarded a $170.7-million guaranteed maximum price design-build contract in July 2002, which has grown by $2 million due to owner-driven scope-of-work additions, including utility mitigation and a 700-ft trench extension.

"ReTRAC is going to help tremendously in keeping traffic moving through the downtown area," says Varela. "[Union Pacific] is talking about having 24 trains a day run through downtown by next year and up to 36 trains daily by 2030."

Historic Priority

The idea of lowering the downtown railroad tracks dates back over 60 years to the Great Depression when the U.S. Bureau of Public Roads proposed elevating the railroad. That idea was quickly nixed in favor of depressed tracks. By 1942 the local chamber of commerce called the project the "number one civic improvement for the readjustment period after the war." Despite this, the rail upgrade never materialized due to its cost and complexity.

Project Details Cost: $265.4 million Duration: 42 months Design-Build Contract: $170.7 million Trench Length: 2.21 miles Trench Depth: 33 ft Trench Width: 54 ft Trench Thickness: 2.5 ft Bridges: 11 Average Bridge Width: 80 ft Average Bridge Length: 59 ft Average Bridge Thickness: 2 ft Excavation: 661,000 cu yd Pilings: 3,000 Backfill: 140,000 cu yds Concrete: 179,000 cu yds Steel: 9 million lb Paving: 1 million tons Peak Work Force: 250 Track Speed: 60 mph Economic Impact: $350 million

But the 1995 merger of the Union Pacific and Southern Pacific railroads gave the project new life. Union Pacific agreed to turn over its 54-ft-wide easement rights and contribute $60 million to the undertaking, making the project a reality. Other contributing funds came from a $50.5-million Transportation Infrastructure Finance and Innovation Act loan from the Federal Highway Administration and Nevada Dept. of Transportation funds. The remaining funds are from city revenue bonds, issued by New York-based Goldman, Sachs & Co., with the debt being retired over 40 years through a combination of a sales, room and property taxes.

Nolte Associates Inc., Sacramento, Calif., which initially conducted some of the early project studies, performed the $4.4-million environmental impact statement from 1999-2000 for Nevada DOT. The firm was later hired by Parsons as a design subcontractor for the bridges, trench and roadways.

After initial design and right-of-way issues, which included some property condemnations, project construction started in September 2002. Granite used a temporary or "shoofly" track to reroute train traffic in order to excavate the trench. The undertaking, however, uncovered some 80 archeological sites, including a prehistoric Native American habitat dating back 4,000 years.

The discoveries added about $600,000 to the project cost for curating and analyzing the artifacts as outlined under FHWA and State Historic Preservation Office agreements. Reno-based MADCON Consultation Services is the environmental/ archeological consultant under a $6.4-million city contract.

"The unexpected find is unlike any site ever discovered in Nevada," says Mark Demuth, a MADCON principal who helped unearth hearths, rock alignments, shell, bone and other items in what became an archeological dig.

Work continued as historic relics were carefully removed and cataloged. Schnabel Foundation, Walnut Creek, Calif., performed 200,000 sq ft of soil nail wall shoring under a $15-million subcontract. Schnabel used a variety of shoring methods, including conventional layback and tiebacks, to excavate to just above the water table. But the project's location near the Truckee River, Reno's main water resource, created some problems.

"The groundwater level was not being dictated by the seasonal runoff, as we had initially thought," says Ron Dukeshier, Granite's project manager. "Instead, it varied throughout the year, depending on peak consumer usage, which presented us with unique challenges."

The contractor reached an operating agreement with local officials to stabilize the fluctuating water levels as trenching work took place. Granite installed its own well, which pumps out 750,000 gallons of groundwater a day. With dewatering under control, it is performing 70,000 cu yd of wet excavation and will install a waterproof cutoff wall and seal slab across the trench bottom, consisting of 30,000 cu yd worth of tremied concrete and eight miles of foundation piles. Condon-Johnson & Associates Inc., Oakland, Calif., drove approximately 3,000 piles, averaging 2 ft in diameter and up to 49 ft deep, as part of a $16-million subcontract.

Granite used conventional hydraulic excavators to dig the trench, hauling the material offsite. Once a river bed, the site yielded a combination of sand, gravel and clay with some large boulders. Due to the alignment, Applied Geomechanics Inc., Santa Cruz, Calif., was hired to monitor eight buildings along the alignment route, including three historic structures dating to the 1880s. The firm installed 36 digital tiltmeters at various route points to record any settlement during excavation around nearby building foundations. The tiltmeters are connected by a wireless Ethernet system, enabling project officials to query and download data from several hundred feet away

Roughly 80,000 cu yd of concrete will form the 2.5-ft-thick, U-shaped trench. "The channel thickness was needed to withstand the structural loading as well as its location below the water table," says Al Lord, Granite's trench superintendent.

As trains run inside the trench corridor, vehicular traffic will pass overheard on 11 precast concrete, two-way tension bridges. The structures average 80 ft wide, 59 ft long and 2 ft thick, weighing 1.4 million lb each. The bridges vary from two to four travel lanes, but each has decorative, stamped pedestrian sidewalks.

"The goal of the project was to create a low-profile, economic bridge structure that could be erected quickly due to traffic restrictions," says Steve Hiatt, Nolte's vice president. "The bridges each have a cavity for running utilities through them as well."

Meeting Goals

Granite faces stringent traffic restrictions that prevent no two adjacent streets from being closed at the same time. For main thoroughfares, one traffic lane must remain open on Third Street, with two available travel lanes on Plaza Street.

Granite must meet five major project milestones with liquidated damages of up to $10,000 a day. The firm has met its first two deadlines, and ReTRAC is now expected to be operational by November, with final completion in early 2006.

The project is expected to increase property values because of the enhancements around the depressed trench. City ordinances mandate that 2% of the project's value, or $400,000, must be applied toward public art. Other improvements include designer benches, lighting elements and sandblasted artwork on bridge walls and columns.

"Our design and construction people worked very hard to meet the city's goals on this project," says Bill Wimmer, Union Pacific's vice president of engineering. "I'm very proud of the effort they put into this."