In the fall of 2003, the Arizona Department of Transportation and its contractor, Edward Kraemer & Sons, Inc., began improving State Route 260 from Payson to Heber.
The project involves widening the two-lane roadway to a four-lane, divided highway and adding five new bridges. Two of the bridges are designed as wildlife crossings to help large animals, such as elk and deer, roam their habitat safely without entering the highway. Reclamation of the old highway and a number of environmental improvements are also part of the $23-million project.
After less than two years, the improvement project is nearly complete. An unusually wet winter caused some delays, but since then the project team has worked hard to make up for lost time. The westbound lanes and bridges are complete. Paving of the eastbound lanes began in September and should be finished by the end of October.
As with previous projects on State Route 260, ADOT has worked closely with the U.S. Forest Service, the Arizona Department of Environmental Quality, the Army Corps of Engineers, the Arizona State Historic Preservation Office, the Advisory Council on Historic Preservation, the U.S. Fish and Wildlife Service, and the Arizona Game and Fish Department to preserve and protect the natural resources contained in this beautiful area.
Not all bridges are alike
You might have noticed that the five new bridges along the new and improved State Route 260 don't all look alike. That's because two different bridge types were chosen based on variations with the project area. The two bridges spanning Tonto Creek are post-tension bridges, meaning the bridges were tensioned with cables -- they run horizontally through the bridge for strength and support - after the bridges were in place. Post-tensioning is costly because it's very labor intensive, but this approach brings an important benefit to sensitive environments. The strength of a post-tension bridge gives it a long "clear span," meaning fewer piers are needed to support the bridge from below. This is especially important near Tonto Creek, where the goal is to cause as little disturbance as possible to this delicate area.
In contrast, the two wildlife bridges (near milepost 268) and the bridge at Thompson Draw are I-girder bridges. I-girder bridges cost far less than post-tension bridges because they're prefabricated and pre-tensioned before they are placed -- a process that requires far less labor than post-tension bridges. I-girder bridges are a cost-effective solution when there aren't as many environmental sensitivities to consider.
The eastbound bridge over Tonto Creek has approximately 360,000 feet of steel cable running through it. On the westbound side, more than 315,000 feet of cable gives the bridge strength and support.
Safe crossings for wildlife
Collisions with wildlife are one of the biggest threats to motorists on SR 260 in the Tonto National Forest near Payson. Several major traffic accidents occur each year when large animals, such as elk and deer, attempt to cross the busy highway in search of food and water. Reducing this threat to motorists, while preserving habitat connectivity for the deer and elk, was one of the major motivators for the SR 260 project.
ADOT and the Arizona Game and Fish Department (AGFI) began by studying the animals' movement patterns, using GPS collars and infrared video systems. Based on their findings, the project team decided to construct a wildlife bridge in the project area of Indian Gardens near milepost 268. The bridges elevate traffic at these strategic locations (where deer and elk were found to cross most often), allowing the animals to pass safely underneath without being exposed to traffic. Below the bridges, "elk fencing" and escape ramps prevent wildlife from climbing the embankment and entering the highway.
Reclaiming the road
As new segments of SR 260 are completed and put into use, the old roadway is being reclaimed so that it blends into the surrounding landscape. The first step is removing all traces of the old asphalt, guardrails and bridges. Next, these areas are replanted with native plants and trees -- mainly ponderosa pine, juniper and oak -- that were removed from the site before construction began. (They've been housed in a nursery throughout construction until it was time to return them to the project area.) As a final measure, the reclaimed areas are covered with a thin layer of straw that serves as mulch, protecting the plants as they grow and become established. This substance also acts as a stabilizer to prevent erosion.
For more information, contact Arizona Department of Transportation, Payson Construction Office, 200 N. Colcord, Payson, AZ 85541, Dallas Hammit, Prescott District Engineer.
Community information toll-free: 1-888-472-1930, Kathy Jirschele or Carol Oaks.
Source: ADOT Press Release