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, according to project officials.

The vast majority of the new bridge construction will be done “off line” in the area where the Glenwood Shell station now sits, and over the top of the Hot Springs Pool parking lot, Interstate 70 and the river, project engineer Craig Gaskill explained Wednesday night during a public hearing on the project.

Some traffic delays will occur when work starts on the reconfigured intersection and roundabout at Sixth and Laurel, 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 of 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.

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, including 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 right involves diverting State 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 of 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 downtown.

At that point, a one-way “square about” will be in effect. Eastbound traffic will turn right 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 weighed as part of the three-year-long bridge study, and CDOT’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.

“We do feel like we have a solid plan,” said Joe Elsen, CDOT’s lead official on the project. “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 car-pooling 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 also 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 off-season 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.

Glenwood Springs Police Chief Terry Wilson said the detour period will present some challenges in terms of both keeping traffic moving and maintaining public safety.

“There will have to be a lot of public awareness done just to advise people about things like keeping speeds down and dealing with the sheer volume of traffic,” Wilson said.

As long as traffic continues to move, even if its slow but steady, the frustration will be minimized, he said.

Ensuring that police, fire and other emergency vehicles can respond to calls will be another challenge, Wilson said.

But Glenwood Springs has dealt with similar traffic disruptions in the past, such as the Grand Avenue Paving Project a few years ago when the old asphalt surface was replaced with concrete

“We take a zoned approach where we stage vehicles on either side of the detour,” Wilson explained. “Once the detour is operating, we’ll evaluate things to see what makes sense to get people through in the smoothest way possible.”

Neighborhood concerns

Several residents of the downtown neighborhoods along Colorado and Pitkin avenues were on hand for the open house and public hearing Wednesday, offering comments and suggestions about how to make the detour as painless as possible.

Pitkin Avenue resident Bob Gish suggested placing a barrier at Pitkin and Eighth to prevent detour traffic from taking a side route through the residential areas. Such a barrier is already proposed for the corner of Ninth and Colorado, to prevent traffic from continuing onto the one-way section of Colorado.

“Temporary as the detour may be, we are concerned about those impacts,” Gish said. “Not only do we have residents in that area, there’s also a school.”

Gish has already been spearheading an effort to limit the number of U.S. Postal Service semi trucks coming to the downtown post office in that same block. He said he would also like to ensure that any additional large trucks would not be allowed to deviate from the detour route.

Similar concerns regarding the detour have been expressed by residents of the Red Mountain neighborhoods, where access in and out of their homes also stands to be impacted by the diverted highway traffic.

The bridge assessment also acknowledges that some motorists will likely choose to stay on Midland Avenue to 27th Street, although large trucks will still be prohibited due to weight limits.

That would result in a “potential difficulty entering Midland from adjacent driveways and neighborhoods during peak hours,” the document states.