COLUMBIA — After years of planning, the City Council approved a list of 15 priority projects that will be funded by federal grant money meant to promote nonmotorized transportation.
The grant would fund the construction of new shared-use paths for bicycling, walking and running.
Annual cost to maintain a quarter-mile of trail:
Gravel in a non-flood area: $1,320
Gravel in a flood-prone area: $4,226
— Considered by some to be more natural looking.
— Good for flat areas out of flood plains.
— Softer on joints (running).
— Cheaper initial installation cost.
— High ongoing maintenance costs.
— Difficult to maintain consistent surface quality.
— Environmental damage caused by gravel erosion.
— More difficult to use in winter because of soft, wet and dirty conditions.
— Gravel migrates on steep trail slopes.
— Difficult to ride bikes on steep slopes and in loose gravel.
— Difficult to remove silt deposits after heavy rains.
— A dirty surface during and many days after it rains.
— Difficult to meet Americans with Disabilities Act surface standards.
— Less stability for running and walking in loose gravel.
— Best initial surface (smooth, no cracks).
— Slightly less expensive than concrete in initial cost.
— Edges crack with vegetation. To get a 10-foot wide trail, a 12-foot wide asphalt trail must be installed.
— Constant maintenance of cracks, filling and sealing with clay soils.
— Must be completely overlaid about every 8 to 10 years.
— Little structural strength to withstand soil problems below.
— Requires greater initial excavation in order to provide the required rock base depth. This is more harmful to nearby vegetation including trees.
— Impervious surface.
— Best long-term ADA-approved surface.
— Best longevity; should last 20 or more years.
— Best consistency of surface. Does not wash away or break apart.
— Does not wash away in flood areas or on steep slopes.
— Steel reinforcements in concrete help prevent shifting, displacement and cracks formations, causing fewer tripping hazards and barriers for wheelchairs.
— Cleaner surface during and after rains, keeping commuters clean and causes less wear and tear on bikes.
— Does not require gravel base rock, resulting in a smaller impact than asphalt would have on trees.
— Does not result in gravel washing into creeks after every rainstorm.
— Initial installation is more expensive.
— Harder on joints (running).
— Less natural looking than gravel.
The next step in the process of extending the trail network is deciding what these new paths will be made of: gravel, asphalt or concrete.
The draft of the Trail Design Guidelines, which lays out building recommendations, includes plans for materials and trail widths. A draft of these guidelines was endorsed earlier this year by the GetAbout Columbia Citizens Advisory Committee.
The recommendations in the draft favor paved trails, particularly a design that would incorporate a 10- to 12-foot-wide concrete path beside a 5-foot-wide gravel path. The trail would be able to accommodate both foot and wheel traffic, City Park Development Superintendent Steve Saitta said.
"That's a really good compromise," he said of the multipurpose design.
Saitta said not all stretches of the new trails will have the same concrete-gravel compromise or the same dimensions, but the design standard, when adopted, will guide the structure of all the new trails based on the anticipated use and location of each one.
But many Columbians have shown in the past that they favor all-gravel trails, as evidenced by the public outcry following a proposal in 2006 to pave the MKT trail, which was later abandoned.
Ted Curtis of GetAbout Columbia said all-gravel trails would not be the best way to fulfill the project's goal of getting people out of their cars and onto their feet or bicycles. Gravel trails are sometimes inaccessible because of weather or flooding, while paved trails are often lower maintenance, safer and last longer.
Curtis said the majority of the proposed trails are in flood plains.
Curtis also cited the Guide for the Development of Bicycle Facilities, published by the American Association of State Highway and Transportation Officials, which recommended concrete surfaces instead of gravel.
"Hard, all-weather pavement surfaces are usually preferred over those of crushed aggregate ... since these materials provide a much lower level of service and require higher maintenance," according to the guide. "In areas that are subjected to frequent or even occasional flooding or drainage problems, or in areas of steep terrain, unpaved surfaces will often erode and are not recommended."
The upkeep of the entire trail system falls on the Parks and Recreation Department and its maintenance budget, Saitta said. The cost of this maintenance can increase when dealing with gravel rather than paved trails. The Parks and Recreation Department currently maintains about 37.43 miles of trails in Columbia.
"What we find most difficult is gravel is prone to washing during flood conditions," Saitta said.
Gravel paths can also be more costly than concrete or asphalt because the gravel has to be replaced frequently. There are different levels of maintenance among the paving options, as well.
"If we go asphalt instead of concrete, it cracks because of the drying out of clay underneath," Curtis said. "We've gotten the most longevity out of concrete for this area because of the high clay content."
According to the Parks and Recreation Department, the average annual cost to maintain a quarter mile of concrete trail is $745, compared to $2,168 for asphalt and $4,226 for gravel in a flood area.
Paved trails also help the city comply with standards set out in the Americans with Disabilities Act.
"It has to be a firm and stable surface," Curtis said of the ADA trail requirements. Not complying with such standards can open up the city to liability, he said.
Columbia does have some all-gravel trails, most notably the MKT trail. But that trail doesn't have the usual flooding problems of gravel trails, Curtis said. The MKT Trail is elevated on an old railroad bed, which helps prevent erosion and standing water. However, this kind of trail is not an option for the city's expansion project.
"We couldn't even get the permits to build a trail like that now," Curtis said. "With all the federal regulations, it would be very difficult and destructive to the environment (to build)."
Currently, plans are being developed for the construction of each individual trail. After being submitted, the plans must go back through public meetings, said Public Works Department spokeswoman Jill Stedem.
"A few projects have preliminary designs, but those have not been approved and could still change at this point," Stedem said.
Although there are currently no meetings scheduled to discuss trail surfaces, Saitta said that discussion will be forthcoming.
"It's got to come," he said. "Standards must be adopted fairly soon to tell consultants what we're going to build the trails out of."