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Sexton climbing lane construction a blast on Interstate 5

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This summer, Interstate 5 highway construction is a blast. Literally.

A $28 million project repaves 17 miles of I-5 from Hugo north to Glendale, improves the curves in the southbound lanes south of Smith Hill, and builds a northbound climbing lane over Sexton Summit.

Climbing lane construction requires several nights of blasting through mid-July.

Rock blasting, especially next to I-5, requires good planning and timing.

“The contractor prefers to blast in the evening when there is still daylight,” said ODOT Project Manager Ted Paselk. “The trade-off is traffic volumes are higher at that time than if we were blasting in the middle of the night.”

To keep traffic moving, ODOT employs rolling slowdowns. Using pilot vehicles, ODOT slows I-5 traffic to about 30 miles an hour from both Glendale and Rogue River. I-5 on-ramps in the project area are temporarily closed during the rolling slowdowns.

“The rolling slowdowns give the contractor at least 20 minutes to blast and clean up any rock that blows onto the highway,” Paselk said.

Climbing lane construction required the closure of the emergency shoulder on I-5. Prime contractor Knife River Corporation of Central Point placed concrete barrier in the work zone so equipment can begin the widening process.

“Driving on I-5 may take a little longer,” said ODOT Project Information Specialist Dan Latham.

Latham said northbound I-5 traffic, depending on the time of day and season, may encounter delays and congestion as slow moving vehicles remain in the slow lane.

“Until we transition into the paving stage on the climbing lane, traffic will remain separated from the heavy equipment needed to excavate the slope for a new travel lane and shoulder,” Latham said.

The 12-foot climbing lane will run on about 2.8 miles, starting as an extension of the Hugo

(exit 66) interchange’s northbound on-ramp, ending just beyond the crest of the Sexton Mountain pass. The climbing lane is being built where the shoulder currently exists. A new 10-foot shoulder will be built to the right of the climbing lane.

“Drivers need to keep an eye on the flow of traffic and watch out for slow-moving vehicles and quick lane changes,” said Latham.

Prime contractor Knife River Corporation is also currently working on Old Highway 99 and around I-5 exit 66. Motorists should use caution and watch for workers and equipment along the highway.

“The project is moving about 250,000 cubic yards of soil and rock to make room for the climbing lane,” Paselk said.

The material is being transferred to three areas along I-5 — the Merlin interchange, the Hugo interchange and slightly north of the Hugo interchange along Old Highway 99 — enough to fill nearly 14,000 18-yard dump trucks.

“These fill locations reduce the hauling cost and, by extension, reduce the overall project cost,” said Paselk.

Steep climbs

Some of the steepest grades on the Interstate Highway System are located on I-5 in southern Oregon.

Commercial trucks have used the I-5 shoulders, designed to provide a safe refuge for disabled vehicles, to navigate southern Oregon’s mountain passes. Trucks using the shoulder cause significant damage that requires frequent repair.

“Southern Oregon’s mountain passes are a weak link on the corridor,” said ODOT Project Leader Mark Leedom, who managed design for the I-5: Glendale to Hugo Paving & Sexton Climbing Lane project. “On each steep climb, trucks slow down in the outside lane, which results in immediate congestion on the pass, increasing the possibility of crashes.”

While most freeway climbs are built on grades of 5 percent or less, the northbound I-5 lanes on Sexton Mountain present a 6.13-percent grade. Trucks frequently slow to less than 30 mph during the climb. The speed difference relative to other traffic can be hazardous.

“The Federal Highway Administration identified that some of the worst truck bottlenecks in the nation are caused by steep grades on I-5 in southern Oregon.”

When one commercial truck attempts to pass another slow-moving vehicle, both I-5 lanes are blocked, forcing traffic to brake hard or suddenly change lanes to avoid a collision. Some trucks drove along the shoulder but this left no room for disabled vehicles.

The new climbing lane is expected to reduce the frequency of I-5 closures related to commercial trucks, especially during winter driving conditions. The new climbing lanes are being built to today’s engineering standards, thereby reducing the need for on-going shoulder maintenance.

More truck climbing lanes

ODOT recently constructed three short climbing lanes, each roughly one-mile long, on I-5 in Douglas County. The truck climbing lanes are located southbound at Rice Hill (milepost 147) and one in each direction on ‘Gumby Hill’ (milepost 137) the steep grade located between Sutherlin and Oakland.

Climbing lanes can also be found further north on I-5 (a 3-mile lane south of Salem) and on Interstate 84 (a 7-mile lane east of Pendleton).

Other potential truck climbing lanes have been identified in southern Oregon, although no other projects are currently funded. ODOT will continue to build on its past success of incorporating truck climbing construction into I-5 repaving projects.

“The benefits of truck climbing lanes extend well beyond Oregon to the neighboring states of Washington and California,” Leedom said.

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