Oregon DOT Eases I-5 Congestion with Auxiliary Lane Project
Better Commuter Connections: Oregon DOT Greatly Reduces Travel Time with I-5 Paving and Auxiliary Lane Project Near Portland
When determining how long it will take to get somewhere during rush hour, the answer always begins with the words, “It depends on traffic.” Along I-5, in the Portland Metro Area, the route was regularly backed up. Hence, the I-5 Paving and Auxiliary Lane Project, which will significantly reduce the amount of congestion along the route and give commuters more certainty.
Just how congested was I-5? There was regular congestion for five hours each day. The Oregon Department of Transportation (ODOT) defines congestion as 75 percent of free‐flow speed, which in this case is about 44 miles per hour.
ODOT conducted a Corridor Bottleneck Operations Study (CBOS) that identified areas where congestion was recurring. The CBOS recommended low-cost, highly effective solutions to improve safety and reduce congestion at these locations. In this case, auxiliary lanes were the recommended solution.
Auxiliary lanes, which typically provide a direct connection from one interchange ramp to the next, reduce bottleneck congestion. Because auxiliary lanes separate on- and off-ramp merging from through traffic, they require less weaving and merging, reducing congestion in all lanes. They also improve safety since many bottleneck locations are also high-crash sites. Crash incidents increase congestion levels, causing more delay and longer recovery time for the freeway.
The I-5 Paving and Auxiliary Lane Project extends an already existing lane. Other aspects of the project include adding a second lane at an exit ramp and other on- and off-ramp lane modifications. Retaining walls, lighting, striping, and sign bridges are also being added, and an overpass structure is being widened.
Another major aspect of the project is the repaving of 5.5 miles of I-5. This repaving is not part of the typical schedule for ODOT. However, doing this along with the project was opportunistic. “We typically repave every 10 years,” says Matt Freitag, an Area Manager for ODOT.
Freitag, who is overseeing this project and has a team of project managers under him, added, “We accelerated the paving schedule for this portion of the road because we determined that doing all the work in a single project minimized construction related disruptions for commuters and would lead to a cost savings.” It is expected that the work on I-5 will extend the service life of the road for another 10 to 15 years.
Budget and Schedule
The construction budget for the project is just over $30 million. The project, which is being funded primarily by federal funds, is on budget.
In addition to being on budget, the project is one year ahead of schedule. Opened for bidding in October 2017, construction began in early 2019. Freitag, says construction was essentially completed by the end of 2019. The original expectation was that the project would take two full construction seasons.
However, the contractor made a proposal to knock off one year from the construction. “We looked at their proposal and ultimately accepted it,” says Freitag. The proposal included a financial incentive, of $2 million, which the contractor would collect if they managed to take a year off.
Cutting the time in half is a significant reduction. Freitag says the solution to getting the work done was straightforward, “They threw more manpower at it.” The contractor had multiple paving crews and grading crews operating simultaneously. “This was possible since the project was straightforward in terms of staging,” says Freitag. “Not a lot of innovative staging was necessary.”
While the staging may have been simple, dealing with the massive amounts of traffic was complex. The interstate, which leads to the southern suburbs of Portland that have grown a great deal in the last 20 years, experiences an average daily traffic volume of 151,000. An added complexity was the team was limited on lane lost hours with closures only happening at night.
Real time signs were added to the route. These signs give commuters valuable information they can use to inform their decisions on the best route to take. “With these variable signs, commuters are informed about congestion, so they know when to start slowing down and what’s coming up ahead,” says Freitag.
The signs are an expansion of the network that is already in Oregon. Earlier deployments of the signage led to significant benefits. “Real time signs were added on an area on Oregon 217,” says Don Hamilton, a Public Information Officer for ODOT. “The first year the signs were installed, the area saw a 21 percent decline in crashes.” Because of this, Hamilton and ODOT see the signage as an important piece of the transportation puzzle.
With all the changes, it is expected that average hours of congestion will drop to one hour. The CBOS study found that this would mean $4.2 million in annual savings for commuters. While this figure comes from many considerations, they include loss time at work and personal time. No surprise then that ODOT has already received a great deal of positive responses from the public who are noticing significant benefits.
The I-5 Paving and Auxiliary Lane Project in the Portland metro and the Clackamas, Multnomah, and Washington Counties area will mean the end of regular backups for commuters. There will be improved connection, less weaving, a reduction in lane changes, and greater safety. The project will increase trip reliability. “Commuters can more reasonably expect when they leave their home and what time they’ll arrive at their destination,” says Freitag. Certainty, or at least near certainty, is priceless.