SUSTAINABILITY: Tender lava

John Ochwat and Ted Stewart, P.E. / February 10, 2011

The Dalles-California Highway, also known as U.S. 97, is central Oregon’s busiest highway, running north-south through the entire length of central Oregon east of the Cascade Mountain range.

Along the way it bisects the city of Bend, Ore., (pop. 82,000). Just south of Bend, the highway passes through the environmentally sensitive Deschutes National Forest and Newberry National Volcanic Monument, near the forested resort community of Sunriver.

The highway serves as a limited-access expressway through Bend and near Sunriver, but almost 4 miles of two- and three-lane highway between the two destinations did not satisfy existing travel demands or safety standards. At several important recreation sites such as Lava Lands Visitor Center, Lava River Cave and Cottonwood Road, there were not safe ways to access and exit the highway. With the volume of traffic on the corridor between Bend and Sunriver predicted to increase from 20,000 daily vehicles in 2008 to 33,000 in 2028, the highway needed improvements.

The Portland, Ore.-based civil engineering firm of David Evans and Associates Inc. (DEA) was selected to design an $18 million safety and capacity upgrade of approximately 3.8 miles of U.S. 97. The project presented a number of challenges, including working in a national forest, working in lava fields, excavating lava rock and protecting wildlife habitat—but along with the challenges came some innovative solutions to meet them.

Deer in spotlight

Long before alternatives were considered and design began, DEA biologists were out in the field, surveying the vegetation and wildlife habitat. DEA Ecologist Phil Rickus undertook surveys to compile a biological resources technical report as part of the environmental assessment and did a separate biological evaluation for the Forest Service, a requirement for any work on Forest Service land.

Rickus surveyed goshawk, a bird of prey, mule deer, elk, black bear, American marten, and even lizards, snakes and frogs that migrate from the nearby Deschutes River. Because of all the animal species affected by the road, one of the challenges was to fully document the impacts of the no-build and build alternatives.

A major issue on that stretch of highway is millennia deer crossing the road. They spend the winter east in southeast Oregon and spend the summer west of the highway in the Cascade Mountains. When the deer migrate, they tend to move east-west in a particular corridor between two lava fields, but they avoid the lava fields themselves.

The Oregon Department of Fish and Wildlife has been conducting a long-term study of the deer population and found that lately the deer’s movements have changed. Much fewer were crossing in the project area, and instead were crossing the highway farther south where the traffic is lighter. Despite the change in their migration pattern, many deer were getting killed on the road, and other crashes were caused by vehicles attempting to avoid the animals. Thus, one of the project’s challenges was to accommodate the predicted growth in traffic without further decreasing the animals’ ability to migrate east and west.

Dealing with crashes head-on

But the local fauna was only one part of the safety equation. To accommodate more traffic, the design called for the highway to be divided and separated by a forested median that is 100 ft wide. Dividing the existing two- and three-lane highway will increase capacity to four lanes, two in each direction.

Dividing the highway also eliminates the safety issue of crossover and head-on accidents. “That stretch of U.S. 97 has the highest north-south mountain pass in central Oregon,” said Jay Davenport, P.E., who is managing the project for the Oregon Department of Transportation. “At an elevation of 4,510 ft, it gets a decent amount of snow and ice. If you had two-way traffic, you can just imagine the severity of the accidents.”

Limiting direct access to the highway also makes the road safer. Prior to the new design, there were intersections at the Lava Lands Visitor Center and the Lava River Cave area on opposite sides of the highway a little more than a mile apart. The design eliminated direct highway access to Lava River Cave, reconnecting the site’s original entrance to the Forest Service road that had served as the highway until it was relocated in 1953. The mostly gravel highway is being improved and paved for over 1.5 miles to serve as a frontage road to connect the Lava River Cave site to a new Cottonwood Road interchange. The frontage road extends to a new bridge crossing under the highway that will allow vehicles, bicycles and pedestrians to move between the cave site and the Visitor Center without accessing the highway.

Davenport said the facilities, part of the Newberry National Volcanic Monument, are a “huge tourist attraction for the area, and a huge safety concern, especially for traffic trying to get back to Bend.” Before the project, vehicles heading from the Visitor Center back to Bend had to make a left turn across a four-lane highway. The Visitor Center still has limited access to the highway, but the junction at the Visitor Center is now right-in only, with a gated right-out access to allow winter use of the site without plowing the frontage road. During most of the year, vehicles returning north will use the frontage road to access the highway at the Cottonwood interchange.

With the wide median and safer accesses addressing the most severe intersection and head-on accidents, the design team sought ways to reduce the number and severity of the other most common crashes on the highway. The design improved the highway’s clear zone to reduce the likelihood of serious run-off-the-road accidents. The team also worked closely with the Forest Service and other agencies to reduce the number of animal collisions to make the road safer for people as well.

Crossing in

Just to the west of U.S. 97 at the north end of the project sits Lava Butte, a steep, conical hill of volcanic fragments known as a cinder cone, the result of a volcanic eruption roughly 7,000 years ago. The eruption’s lava flows permanently changed the terrain, leaving lava caves (one runs under the highway), and a series of channels in the terrain. While the lava cave presented some challenges to building the road, the channels gave DEA a unique opportunity to accommodate both wildlife and motorists in the forest. Since the channels cut across the path of the road, the migration patterns of the deer and elk follow the slope. DEA’s solution was to construct bridges to carry the highway over two of these channels to provide crossings for animals. One of these locations was already being designed for the frontage-road crossing, so the bridge designs were enlarged to create one of the wildlife crossings parallel to the frontage road. The second pair of bridges was designed exclusively for wildlife use about 2.5 miles south of the crossing shared with the frontage road.

Though the crossings are the first in the state of Oregon, they are not the first in the U.S. There are specifications from the states of Washington, Alaska and other sources that guide the minimum size and emphasize that the crossings have to look as natural as possible to the animals that use them. To ensure that the deer use the crossings, an 8-ft fence is planned on both sides of the highway for the entire length of the project. But since the highway is divided, and there are interchange roadways the fence cannot cross, another challenge is preventing the deer from getting inside the fences or onto the median.

To prevent that, the roadways crossing the wildlife are being equipped with Electromats, a 4-ft-wide electric mat that is embedded in the roadway. The mats function like cattle guards at the access points, extending across the road shoulders to the wildlife fencing on each side of the roadways to shock animals that start to cross into the fenced area.

Greening the road

Well into the alternatives analysis, DEA Project Manager Mike Hohbach received photos of the project one of his clients had taken from a helicopter. The photos showed that during construction of the adjacent South Century Drive interchange, a separate contractor had stripped every tree in the vicinity. ODOT’s project manager during the design called Hobach and said, “Our project had better not look like this.”

“So that set the tone for our projects,” Hohbach said. “We tried to make it the least impact to the area and the forest as possible. We saved median trees as much as we could, so in theory, you couldn’t see from one side of the road [to] the other. As a result, from Lava Butte you can’t really see the highway, so that’s a good thing.”

The commitment to preserve trees also drove the selection of the old highway roadbed for the frontage road, eliminating the need to clear another corridor. Preserving the visual and habitat resources of the forest was an important consideration during the project’s development. In addition to the wildlife crossings and the pedestrian and cyclist access, some of the project’s other environmental and sustainable innovations included:

  • Processing the cleared vegetation from the project on-site to use as duff material;
  • Designing the bridge structures to provide crevices for bats to roost; Texturing and pigmenting the bridge abutments to make them blend with the natural geology; and
  • Coordinating the project’s frontage road and accesses with the Forest Service to allow them to close and revegetate some of their roads so that the revegetated area is roughly equivalent to the new pavement that was added.

    These efforts are not surprising for three reasons: First, the project is in a national forest. Second, sustainability is part of DEA’s core purpose. And third, because ODOT included Lava Butte as one of four statewide pilot projects to evaluate the Greenroads sustainability rating system.

    “What we’re doing now is analyzing how well Greenroads works with our projects,” said ODOT Research Coordinator Lyn Cornell. “A major concern is whether compliance increases our costs unreasonably.”

    Greenroads, developed by the University of Washington and CH2M Hill, is one of several proposed sustainability rating systems, and it encourages projects to move beyond minimum compliance by recognizing innovation. Thus, the program has 11 project requirements, currently another 37 voluntary credits and also allows organizations to propose custom credits. It is similar to LEED in that way and the way it awards certificates with four levels of recognition: Certified, Silver, Gold and Evergreen.

    The Lava Butte project earned enough overall points to qualify for the silver rating, except that three Greenroads project requirements were not met. The Greenroads case study was a retroactive application of the new metrics after the project design and specifications had already been completed and construction half completed, so they could not be added. One example is that the project incorporated noise-mitigation procedures in the project specifications, but did not require the contractor to produce a formal Noise Mitigation Plan, as required by the current Greenroads Manual. The Greenroads Pilot Project Report stated one other requirement was not met because it is “not a standard practice for ODOT projects,” and two other required plans could have been included in the contractor requirements with “very little time and effort.”

    Even though the project did not achieve formal certification, Cornell is positive about the experience and optimistic about the program’s future.

    “I think Greenroads will be really beneficial to ODOT and other departments of transportation,” she added. “It brings up options you may not have thought about, like different methods of handling water removal and drainage. Different choices have various points assigned, and some choices are worth more than others. There’s also a category you can customize for each project, to include items that don’t fit into standard categories. Greenroads works as a designing and construction tool.”

    Initial work on the project began in April 2009. The new northbound separated lanes are complete and started carrying traffic in October 2010. The old highway is in the process of being converted from two-directional to single-direction for southbound traffic.

    The wildlife crossings on the northbound side of the highway are complete, but the crossings under the southbound side are being constructed. The last step of the project will be to install the fencing on the sides of the highway to route the wildlife through the crossings. The entire project is scheduled to be complete in November 2011.

About the Author

Ochwat is a communications manager and Stewart is a senior transportation design engineer with David Evans and Associates, Portland, Ore.

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