Washington DOT Gives Interstate 5 New Life
Roadways don't last forever. In northwest Washington state, Interstate 5 is 50 years old and in need of a refresh. Enter the Washington State Department of Transportation (WSDOT)'s #ReviveI5 project. This $31 million low-bid effort, funded primarily by a nickel gas tax launched in 2003, stretches from Kent in the south to the Duwamish River in Tukwila to the north, and is intended to fix some age-related issues that have arisen over the years.
Though the materials used in the original construction of I-5 were designed to last only about 25 years, they held up better than anyone anticipated. However, the time has come to rehabilitate a section of the northbound freeway and improve conditions for the 100,000 vehicles that use the segment each day. "The project is pretty broad," explains Mike Askarian, Project Engineer for WSDOT.
Multiple Approaches, One Goal
One continuous stretch of roadway is impacted by the project, but the work being done has been broken into several chunks based on the repair processes each section requires. The project's full length encompasses 8.6 miles of I-5 and has two primary facets.
The center section, about 4 miles long, will be revitalized using crack, seat and overlay. "You break the concrete panels, and then you pave over it with asphalt layers," Askarian explains, adding that, after the broken substrate is compacted, "You put about 2 inches of layers of asphalt on top until the thickness reaches about 9 inches." It's a process that includes an opportunity to reduce waste, which WSDOT takes advantage of as much as possible. "Our contractor recycles the concrete material into the substrate," Askarian says. "By breaking the concrete panels in place, we reduce the amount of concrete that's taken to landfills."
Another 4.6 miles - a little more than 2 miles at each end - features diamond grinding of the concrete panels that currently make up the road surface. The grinding will help to get rid of the ruts that have formed over the years, which hold water and reduce traction for drivers.
Scattered across the entire project, WSDOT expects to replace a total of about 440 individual broken concrete panels.
The #ReviveI5 project also includes two bridges within its scope. One is the Duwamish River Bridge, the other is the Interurban Avenue overpass. Both are in the city of Tukwila, near the project's northern end. "We're replacing the expansion joints and doing some deck repair on those two bridges," Askarian says. Decades of wear have degraded the expansion joints, eight of which are scheduled for replacement during the project. Improvements to the road surface are also part of the planned rehabilitation. Additional components in the project range from ADA improvements on the bridges to the installation of traffic volume counters.
Complex Scheduling in the Heart of Commute Territory
This project, focused on the northbound lanes, follows earlier efforts on the southbound side of the freeway. "Over the last two years we were working on southbound, but doing the same kind of work," Askarian says. Now it's northbound's turn. "We've scheduled it as funding has become available and we have the time to program it." Often planned two to four years in advance, the WSDOT team still needs to work around inclement weather and budget availability. As for mitigating effects for drivers, Askarian says, "Our weather means most of the work is done in the summer, but the impact to traffic will be there no matter the time of year."
Given the scope of the lane closures necessary to complete the work, WSDOT has tight limits on when and how much traffic can be impacted. Much of the work takes place at night, plus some weekends. And though lanes can generally be closed beginning at 8 p.m., they must be open again to traffic by 5 a.m. Additional constraints come into play when large events are occurring in the area, such as concerts or games. "If more than 25,000 people are attending those events, we need to work with the venues or the teams," explains Tom Pearce, Communications Consultant for WSDOT. "There are times when we can't work a weekend because it will create too much traffic." Outreach to the public has helped significantly, with travelers being reminded of available alternate routes and kept up to date whenever a closure is planned.
Though drivers may find the long stretches of construction work tedious, Askarian says there are advantages to bulking up on the amount of work that's done within a single project. "If you break it into smaller pieces, you're coordinating different contractors and that timeline might extend to three years instead of 18 months." Traffic mitigation may also be more problematic if multiple contractors are staging work a simultaneously. "This way, it removes that kind of conflict by working at the same location," Askarian explains. Advertising costs are reduced when the work is folded into one broader project. Similarly, the team can dedicate fewer hours to tackling the various approval and planning processes, as opposed to conducting those same efforts several times to cover everything.
A few disadvantages come along with larger projects such as #ReviveI5, but Askarian stresses they're minimal and still offer a good trade-off for all the benefits that are gained. One is simply the sheer amount of work that must be coordinated and executed. "The impact to construction offices like ours is needing to provide the workforce to manage all the different types of work," he explains. Another is partnering with a contractor who has the resources to identify and efficiently schedule the various activities. "Overall, I think the advantages far exceed the disadvantages," Askarian says.
Accomplishing an expansive project takes solid teamwork and expertise. "We have a good team with the experience to do this kind of work," Askarian says. "We have a good inspection crew, a chief inspector and office people who are really dedicated." With around-the-clock field work occurring over 10 non-consecutive weekends, good communication has also been crucial. Pearce and the rest of the communications team have helped Askarian's group maintain contact with the media, as well as facilitating weekend conference calls to ensure the top management is aware of the project's status, any pending issues and how traffic impacts are being handled. Keeping everyone informed - within the project team and across the public who count on I-5 for their daily travels - can be a complicated undertaking, particularly when weather cancels planned work at the last minute. "We can be planning to begin work on Friday, but our project is weather dependent and some things can't be done in the rain," Askarian says
Valuable Lessons from the Program
WSDOT's prime contractor, Gary Merlino Construction, has helped to bring down the amount of time needed to accomplish certain portions of that work. "They decided to have some initiative to build some precast concrete panels," Askarian explains.
The panels, which are 12 feet wide, 15 feet long and 9 inches thick, can be quickly put in place as a temporary measure after a damaged panel is removed. This has helped accelerate the replacement process significantly in a project where the ability to impact lanes of travel is limited. By using these precast panels, the old panels can be removed and temporary panels used until the next night, when the contractor is able to complete the process by removing the temporary panel and pouring the permanent concrete replacement. "It has improved efficiency, so instead of doing only three panels each night, they've been doing six or eight panels," Askarian says.
The approach has been so successful on the #ReviveI5 project he hopes to leverage it the next time WSDOT's work calls for concrete panel replacement. "It's not all engineering," Askarian says. "It's related to impacting the traveling public, as well."