With most construction work conducted off Interstate 5 during the winter, motorists might be inclined to think the I-5: Glendale to Hugo Paving and Sexton Climbing Lane project is finished.
However, that’s not the case. Work continued on curbs, inlets and erosion control.
Once the weather improves (drier and warmer), prime contractor Knife River Corporation of Central Point will tackle a short list of items to wrap up the $28 million improvement project.
“When it warms up, we’ll work on the Sunny Valley (exit 71) and Glendale (exit 80) bridge decks, along with some final paving, striping and fencing,” said ODOT Project Manager Ted Paselk, “and then the project will be a wrap.”
By late last summer, the most visible work — excavation and rock blasting to construct a new, northbound Sexton Mountain truck climbing lane — wrapped up, allowing Knife River Corporation to transition into paving and striping work and making safety improvements along the project’s
17-mile stretch of I-5 from Hugo north to Glendale.
The project’s safety improvements included adjusting the southbound curves located south of Smith Hill.
The new 12-foot climbing lane for commercial trucks, notorious for a slow climb over Sexton Mountain, extends 2.8 miles from the northbound on-ramp at the Hugo (exit 66) interchange and ends just beyond the crest of the Sexton Mountain pass. The climbing lane was partially built on the former shoulder, which was replaced with a new, 10-foot shoulder built to the right of the truck climbing lane.
Last summer, ODOT used rolling slowdowns to keep traffic moving during the blasting stage. Pilot vehicles slowed I-5 traffic to roughly 30 miles an hour from both Glendale and Rogue River. I-5 on-ramps in the project area were also temporarily closed during the rolling slowdowns.
“The rolling slowdowns gave Knife River about 20 minutes to blast and clean up any rock that blew onto the highway,” Paselk said.
Climbing lane construction required closing the I-5 emergency shoulder and placing concrete barriers to separate traffic from construction work. According to Paselk, an estimated 250,000 cubic yards of soil and rock were moved to clear room for the new northbound truck climbing lane.
Knife River transferred the material to three locations along I-5 — the Merlin interchange, the Hugo interchange and slightly north of the Hugo interchange along Old Highway 99.
“There was enough material to fill nearly 14,000 18-yard dump trucks,” Paselk said. “Most importantly, these fill locations reduced the hauling cost and, by extension, reduced the overall project cost.”
Motorists encounter many of the steepest grades on the interstate highway system in southern Oregon.
The I-5 shoulders, designed to provide a safe refuge for disabled vehicles, are sometimes used by commercial trucks to navigate southern Oregon’s mountain passes. Trucks using the shoulder cause significant damage that requires frequent repair.
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.
When one truck attempts to pass another slow-moving vehicle, both lanes are blocked, forcing traffic to brake or change lanes to avoid a collision. Some trucks drove along the shoulder but this left no room for disabled vehicles.
ODOT expects the new climbing lane will reduce the frequency of I-5 closures related to commercial trucks, especially during winter driving conditions. The new climbing lane is built to today’s engineering standards, thereby reducing the need for ongoing shoulder maintenance.
More truck climbing lanes
Over the past couple of years, ODOT added 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 (exit 136) and Oakland (exits 138 and 140).
Truck climbing lanes are also located further north on I-5, where a three-mile section exists south of Salem, and on Interstate 84, which has a seven-mile section east of Pendleton.