Building Better Roadside Rest Areas in Montana

Rest areas are important fixtures along American highways. They offer drivers and their passengers a place to rest and refuel before returning to the road. In heavily populated states, options for stopping tend to appear frequently on interstate highways. In rural locations, however, the distance between rest areas tends to be greater. In a state like Montana—the nation’s fourth largest by land mass but 44th by population—it is critical, then, that these facilities are up to date to fully serve the needs of travelers.

Three of Montana’s rest areas—the Divide Rest Area on Interstate 15, Columbus Rest Area on I-90 and Hysham Rest Area on I-94—were constructed in the 1970s. The Montana Department of Transportation (MDT) wanted to overhaul each to increase public safety, decrease maintenance costs and provide more aesthetically pleasing and functional break locations for drivers. To achieve those goals, MDT hired CDM Smith’s integrated design-build team to lead the effort.

Calling All Experts
Each rest area had an accelerated schedule of approx­i­mately 1 year. CDM Smith’s team began with the $5.19 million Divide Rest Area, continued with $6.9 million Columbus and finished with $7 million Hysham.

According to CDM Smith project manager Darrel Stordahl, diverse technical expertise was required to success­fully deliver each facility: archi­tec­tural, civil, geot­ech­ni­cal, structural, electrical, mechanical, envi­ron­men­tal, water and wastewater, utilities, and traffic control and signage. “These projects were great,” he said, “because they let us combine a lot of what we do best as a company.”

The three projects had many simi­lar­i­ties. CDM Smith’s trans­porta­tion engineers expanded site parking lots signif­i­cantly to account for both cars and trucks, while considering safety and func­tion­al­ity, snow removal activities and stormwater management. Each site included LED lighting of the parking areas, as well as two well-lit picnic shelters with tables, benches and space for pets.

The rest area buildings, which were designed by CDM Smith team member CWG Architects, were engineered to be safe, durable and cost effective, with safety features including Americans with Disabil­i­ties Act compliant private and family-style restrooms, spacious vestibules, adequate windows to increase natural lighting and three exits per building.

CDM Smith’s envi­ron­men­tal engineers completed stormwater pollution prevention plans for the rest areas, applying erosion and sediment control management practices throughout construc­tion to prevent sediments from leaving the construc­tion sites.

Another important shared component was wastewater treatment. “At rest areas,” said Stordahl, “starting wastewater biological concen­tra­tions are much higher than what is treated in residential areas, where the addition of grey water from showers and washing machines dilute the wastewater concen­tra­tions.” Stordahl noted that because of their remoteness, Divide, Columbus and Hysham could not tie into city sewer systems. Adding to that fact, Montana has non-degradation laws that set strict discharge limits to protect against watershed pollution. To overcome these hurdles, CDM Smith’s team installed wastewater treatment systems underground at each location, including three 15,000-gallon tanks where waste is aerated and denitrified. “These systems are pushing the limits of the tech­nolo­gies,” said Stordahl, “removing 95 percent of the nitrogen to send water into the drain fields that will meet Montana’s stringent require­ments.”

Addressing Unique Challenges
Though the facilities ultimately resembled each other, the team had to contend with certain site-specific constraints and require­ments. For example, soil composition differed by location, requiring varying levels of earthwork design and exploration. At Columbus, subgrade soil char­ac­ter­is­tics encountered on the westbound side of I-90 did not match initial testing results, so CDM Smith’s team had to redesign the facility’s pavement structure to address the existing conditions.

Hysham’s remoteness created logistical challenges for the team. Because it is an hour away from the closest major city, it was vital to maintain the quality of materials, like concrete and asphalt, as they traveled to the site. To keep costs down, CDM Smith’s experts identified oppor­tu­ni­ties to reuse existing site materials. 

Divide’s scope included construc­tion of a MOVE (Mobile Officer Vehicle Enforcement) scale to allow MDT officers to weigh commercial trucks. CDM Smith’s design had to flexibly incorporate the portable scale without interfering with site parking plans, rest area buildings and other civil design components. The MOVE scale was dropped into a concrete approach pad, which MDT staff can easily hook into at any time via a mobile operations trailer that was fabricated as part of the project.

Proving the Power of Design-Build
“CDM Smith has a strong design-build history,” said Stordahl, “but we had not served as the sole design-builder on a trans­porta­tion project before.” MDT was in a similar situation; the department had completed design-build projects before, but with mixed engineering and construc­tion teams delivering the work.

Bringing its integrated team to bear, CDM Smith amped up its collab­o­ra­tive efforts. Under­stand­ing that MDT builds roads and bridges for a living, it was important for the CDM Smith team to communicate clearly about parts of the project that are not as common for them, like the wastewater systems, and to maintain a high level of teamwork throughout.

“CDM Smith and its team demon­strated the full value of an integrated design-build team,” said Jake Goettle, Bureau Chief of MDT’s engineering construc­tion contracting bureau. “The teamwork was so valuable that MDT has made the team integration/project kickoff meeting, first performed on one of these projects, mandatory for all future design-build contracts.”

The focused collab­o­ra­tion took each rest area from permitting to design to construc­tion within a year—an accom­plish­ment that did not escape the team. “Each rest area is slightly different, and you want to keep build costs low while still providing the best alternative,” said CDM Smith’s design project manager Shaheen Siddiqui, PE, P.​Eng. “It was great to see it all come together three times in a row and the little improve­ments we added to each rest area.” “It’s rewarding to watch your design concepts come to life in just a few short months,” stated CDM Smith trans­porta­tion engineer Jake Gunther, PE. “Having that flexibility to make improve­ments during construc­tion helps us provide our client and the public with a great finished product.”

“Typical trans­porta­tion designs can sometimes stretch 3 to 4 years and then you’re not involved during construc­tion,” said Stordahl. “With design-build, you see the results of your work very quickly. In the end, MDT was happy from cost, schedule and quality standpoints. You can’t beat that.”

“These three rest area projects were awarded to CDM Smith on a best value process and they delivered,” said MDT’s Goettle. “Travelers now have safe, clean, appealing rest areas to take a break. MDT now has new low maintenance facilities, well-built with innovative state-of-the-art systems that will be in place for many years to come and serve our customers very well.”