Blessed with dry autumn weather that facilitates highway construction work, the two-year, $28 million project on Interstate 5 is substantially complete.
By late last summer, the most visible work — excavation and rock blasting to construct a new, northbound Sexton Mountain truck climbing lane — had wrapped up, allowing prime contractor 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.
“Erosion control and the draping of the rockfall screens across the slope took us into late autumn,” said ODOT Project Manager Ted Paselk. “We’ve adjusted the concrete barrier and completed storm water drain inlets in the project area.”
The project’s safety improvements included adjusting the southbound curves located south of Smith Hill.
Weather-sensitive bridge deck treatments near Sunny Valley are scheduled for completion in summer 2014.
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.
ODOT used rolling slowdowns to keep traffic moving during the blasting stage last summer. 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 the 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 on I-5 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.
“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,” said ODOT Project Leader Mark Leedom, who managed design for the 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.
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 lane is being 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.