The southern tip of Puget Sound in Washington is a buzz of transportation with boat traffic — both for commerce and for pleasure — railroad tracks, road traffic on Interstate 5 and activity flowing north to Tacoma, Seattle and beyond.
The Washington Department of Transportation (WSDOT) has focused on a project in this area between the city of DuPont and Joint Base Lewis-McChord (JBLM).
Working with contractor Atkinson Construction, WSDOT has supervised work that will decrease congestion and bring new safety measures in a $240 million design-build project that is about 85 percent complete.
This project, the I-5 - Mounts Road to Steilacoom-DuPont Road - Corridor Improvements job, will extend high-occupancy lanes in both directions on I-5, and improve access between the city of DuPont and the military base.
The work also will include constructing a more efficient interchange, which will make traffic smoother and easier for people who walk, ride or roll between the city and the military base. Pendleton Avenue, a key road for the base, will now have more vertical clearance for the bridge over I-5.
The joint base, operated by the Army and Air Force, is a combination of Fort Lewis and McChord Air Force base. It is home to the 62nd Airlift Wing. The base location provides rapid access to deepwater ports for deploying military equipment.
Construction Equipment Guide spoke with Atkinson Construction Manager Mannie Barnes regarding the complex project. One of the major elements of the job involved setting 17 precast girders over the railroad tracks. These girders varied significantly in size, with lengths ranging from 148 ft. to 156 ft. and a maximum weight of 171,000 lbs.
"The team executed a sophisticated hand off girder pick, using two 330-ton crawler cranes in an hour by hour planned operation to safely launch and transfer these large, varying length girders over the tracks," Barnes said. "This precision was matched during the deck pour, where the irregular shape necessitated the use of 1,200 linear feet of screed rails to manage the Bidwell screed and accommodate the unique geometry."
Workers will remove an at-grade railroad crossing, which will increase safety in this busy area. The surrounding roadways will have more capacity, and motorists will no longer have to wait for trains to pass before entering the city of DuPont while merging onto I-5. The new diverging diamond interchange overpass will feature a protected shared-use path for a safe passage for non-motorized users between both communities.
"The design build team developed an innovative solution that combined two planned I-5 crossings into one bridge over I-5," WSDOT spokesman Doug Adamson told Construction Equipment Guide. "This was achieved by building a unique intersection at the JBLM gate and the new interchange."
Materials
The Atkinson team and contractors laid down more than 100,000 tons of asphalt for the project and used 3.2 million lbs. of rebar. Workers also placed 450,000 cu. yds. of embankment and 120,000 sq. ft. of retaining walls.
The team partnered with JBLM to repurpose used materials for current and future use. The construction team diverted timber, wood chips and brush to support on-base landscaping activities. This collaborative recycling program reduced disposal costs and was used as part of the work at the base.
"The new Steilacoom-DuPont Road overpass work that spanned railroad tracks was a major achievement," Adamson said. "The construction team managed a complex, three-stage abutment pour while avoiding conflicts with underground utilities."
Adamson called the concrete pour one of the team's defining challenges, testing the team's mettle to build a deck and splayed wing walls with trapezoidal geometry. The 80-ft. difference between the piers required close work among the builders for the final 750 cu. yd. deck pour. The new deck is approximately 3 in. thicker than a standard bridge deck.
Safety
Safety is often an area where technology can play an important role. Atkinson said it is committed to an "Innovation First" safety culture, seeking out technologies that keep people out of harm's way. A primary focus continues to be minimizing worker exposure to live traffic, which continues to be one of the most significant risks in modern infrastructure projects.
Using advanced portable traffic signals, the Atkinson team was able to replace traditional manual flagging by removing workers from the roadway where they are most vulnerable to inattentive drivers, Barnes said. By using high-definition cameras and sensors, site managers can oversee complex work zones without requiring a constant physical presence on the shoulder or median. Atkinson hopes to use this combination of automation and real-time monitoring to maintain efficient traffic control while ensuring every worker returns home safely.
The project is already making an impact for motorists coming on and off I-5, as well as those needing access to the military base. Workers are rebuilding a major gate at JBLM, reducing congestion for service members, contractors and civilians.
Adamson summarized the activity by saying, "Rebuilding the gate builds on the opening of the new I-5 overpass, which takes people to both northbound and southbound I-5. The new interchange, the new bridge over the railroad, along with the reconstruction of the gate, will greatly improve traffic flow for military and local traffic." ♣
