Detour plans unveiled for Grand Avenue Bridge document
November 20, 2014
Most of the planned, two-year-long Grand Avenue Bridge construction will not significantly impact the flow of Highway 82 and city traffic that will continue to use the existing bridge over the Colorado River to Sixth Street and the Interstate 70 interchange, according to project officials.
The vast majority of the new bridge construction will be done "offline" in the area where the Glenwood Shell station is and over the top of the Hot Springs Pool parking lot, I-70 and the river, explained project engineer Craig Gaskill during a public hearing on the bridge plans Wednesday night.
Some traffic delays will occur when work starts on the reconfigured intersection and roundabout at Sixth and Laurel streets, according to the project's formal environmental assessment that was released earlier this month.
By far, the biggest impact would be during a 90-day detour period, now planned for spring 2017, when the existing bridge is to be taken out of commission to make way for the final segment of the new bridge.
That's when motorists as well as businesses and residents along both the closed section of Highway 82 on Sixth Street and the planned detour route along Midland Avenue and the west side of downtown "will really notice," Gaskill said.
The Colorado Department of Transportation's Grand Avenue Bridge assessment details how that and one other detour would work.
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Two separate detour routes are proposed during the bridge construction, including one for I-70 traffic during about 10 short, nighttime periods when overhead work is to be done, bridge demolition and installation of large segments of the new bridge.
The half-mile long I-70 detour will occur at various points during the bridge construction between 8:30 p.m. and 5:30 a.m., when both eastbound and westbound traffic is to be diverted onto Sixth Street between exit 116 and the Yampah Vapor Caves.
The more extensive detour, however, involves diverting Highway 82 and city traffic heading to either side of the Colorado River during the full bridge closure. That detour will be in place for approximately three months in the spring 2017, according to the construction schedule outlined in the project assessment.
During that time, eastbound traffic is to be rerouted onto Midland Avenue at I-70 exit 114, where several upgrades to handle the extra traffic are planned, and will proceed to Eighth Street and across the existing Roaring Fork River bridge.
From there, traffic would continue onto a new, temporary connection to what's now a dead-end portion of Eighth Street west of Glenwood Springs City Hall and into the downtown area.
At that point, a one-way "squareabout" will be in effect. Eastbound traffic will turn from a temporary traffic signal onto Colorado Avenue to Ninth Street, where it will then reconnect with Grand Avenue/Highway 82.
Westbound traffic, meanwhile, will stay on Grand and turn left at Eighth Street, continuing along the detour route to west Glenwood.
Other options considered
Other detour options were also considered as part of the three-year bridge study, and the Colorado Department of Transportation's project team had originally planned to keep the detour on Midland Avenue all the way to 27th Street and back to Highway 82 at that point.
However, at the urging of city officials, it was decided to instead pursue the Eighth Street connection, all or part of which the city may use for a permanent new street connection once the new Grand Avenue Bridge is built.
"The analysis determined that motorists would experience unacceptable delay without some temporary improvements to intersections and roadways along the route, and a voluntary reduction of peak hour trips," states the section of the bridge assessment devoted to the detour plans.
It also calls for finding ways to reduce the existing level of traffic, both from within and passing through Glenwood Springs, by about 20 percent during the construction period in an effort to minimize traffic congestion.
"We do feel like we have a solid plan," Joe Elsen, CDOT's lead official on the project, said. "The challenge will be to try to get rid of some of the single-occupant vehicles you see out there."
That will mean doing public education and providing incentives to encourage carpooling and riding the Roaring Fork Transportation Authority bus system that runs between Aspen and Rifle as well as the city's "Ride Glenwood" bus system, which is operated by RFTA, Elsen said.
Project planners have been working with RFTA to provide more buses during the detour period in particular. Because it would be the offseason for the Aspen ski resorts, Elsen said RFTA has indicated it would have the extra equipment and drivers available during that time to devote to easing the traffic strain in Glenwood.