GLENWOOD SPRINGS, Colorado - Running a Highway 82 detour on Midland Avenue during construction of a new Grand Avenue bridge is not as simple as taking the traffic that's currently on Grand and transferring it to Midland.
"We will need to look at ways to strategically reduce the existing traffic by about 20 to 25 percent during that 30- to 60-day period," Colorado Department of Transportation project study team member David Woolfall said.
That could be accomplished by providing incentives for commuters to take Roaring Fork Transportation Authority buses, running more in-city bus routes during that period, and relocating bus stops to make them more convenient for locals who are just out running errands, Woolfall suggested during an open house sponsored by CDOT Wednesday evening.
"We will have to see a drop in the level of traffic in order to get the volume into a range that we can accommodate on Midland," he said.
Midland Avenue from Exit 114 on Interstate 70 south to 27th Street is being studied as the likely detour route to be utilized during a two-month period to be determined in 2015 or 2016 when the Grand Avenue/Highway 82 bridge is expected to be under construction.
At some point during construction, a full bridge closure of up to two months would be needed in order to complete the bridge connection from one side of the Colorado River to the other.
Project planners are targeting either a spring or fall shoulder season for the detour. That's when total traffic volume on Highway 82 is usually at its lowest, Woolfall said.
The proposed detour route and related traffic and neighborhood impacts were among several topics discussed in various "conversation circles" during the open house, held at the Glenwood Springs Community Center.
The open house, one of several hosted by CDOT since the bridge planning began in late 2011, drew the largest crowd so far, at more than 150 people.
Many were there simply to learn more about the project, view design options for both the highway bridge and a new pedestrian bridge, discuss a range of side issues and offer their comments.
Among those who attended were residents living along the portion of Midland Avenue at the base of Red Mountain, who were concerned about the prospect of running highway traffic onto the normally quiet, two-lane neighborhood street.
"I'm worried that two months could turn into six months, and what that will do over the long term," said one area resident, George Wear. "For the whole two-plus years of construction, I don't see how they're going to be able to keep that traffic off of Midland."
Despite traffic-control measures, Wear also said he's afraid the 25-mph speed limit on Midland will not be adhered to, same as it's ignored on Grand Avenue currently.
Use of Midland Avenue as a detour route would require several temporary improvements at key intersections in order to accommodate truck traffic and control the flow of vehicles, according to project officials.
Among them would be additional striping, temporary removal of the speed humps between 10th and 13th streets, a temporary traffic signal at either 10th or 13th, and modifications to the 27th Street roundabout to allow for larger trucks.
Left-hand turns from 27th Street onto Highway 82 (South Glen Avenue to Grand) would also be prohibited during the detour period in order to avoid traffic back-ups.
The open house was also heavily attended by citizens who are part of the newly formed "Save Grand Avenue" group. The group is trying to convince CDOT and city officials to halt the bridge planning process in favor of a new bypass/alternate route study.
"Our biggest concern is finding a way to move the highway traffic off of Grand Avenue for good," said Glenwood Springs resident Pam Szedelyi. "The bridge is one thing, but my concern is more about the access control plan and what it is going to do to our city."
Among the recommendations in a separate, draft Highway 82 Access Control Plan are to limit movements onto and off of Grand Avenue from side streets, and to limit pedestrian crossings at some downtown intersections.
"That would completely dissect our city," Szedelyi said during one of the evening's conversations about the process necessary to start a bypass study aside from the current bridge study.
Though the access plan and bridge projects are separate, the planned new bridge would likely be one of the triggers for implementing the access limits.
Replacing the bridge would not preclude a bypass or alternate route option in the future, CDOT's Region 3 program engineer, Joe Elsen, explained.
However, it would be a much more involved, more expensive study, involving a much larger study area than does the current bridge project, he said.
To start that process, bypass proponents would need to work with CDOT, as well as Glenwood Springs and Garfield County officials, to determine the focus of the study and identify funding sources.
It's possible such a study could be included in ongoing discussion with CDOT's Intermountain Transportation Planning Region group, which prioritizes various highway and transportation related projects for future funding, Elsen said.
CDOT is about to enter into a formal Environmental Assessment to further study and refine the bridge replacement plans. The project is in line to receive up to $59 million from CDOT's special Colorado Bridge Enterprise Fund.
A preferred alignment identified by CDOT for the new bridge would carry traffic from Grand Avenue on the south side of the Colorado River and curve west over the Hot Springs parking lot to a reconfigured intersection at Sixth and Laurel streets.
The new alignment would remove highway traffic from the two-block stretch of Sixth Street between Pine and Laurel.
The environmental review is expected to continue throughout this year and into early 2014. After that, another seven months or so would be needed to complete the final design. Bridge construction would not actually begin until early 2015.