Widening Maple Grove

Story by Stephanie Worrell | September 28, 2010

The $11-million widening of Maple Grove Road in Boise has literally been one of the "hottest" roadway projects in Idaho this summer.

The combination of triple-digit temperatures and upwards of 40,000 cars per day passing the project has turned out to be a hot combination for crews working towards an aggressive fall of 2007 completion date. Even so, the project as remained on schedule under the leadership of general contractor Idaho Sand & Gravel Co., Nampa, Idaho.

Maple Grove Road, a major transportation artery running right down the center of the Treasure Valley, is being widened from two lanes to five lanes between Franklin Road and Fairview Avenue. Work has included to date: construction on two pre-stressed concrete bridges, utility relocation, significant irrigation work, curb,gutter and sidewalk, asphalt and concrete paving of two of Idaho's busiest intersections, and asphalt removal and paving on the two-mile stretch.

From start to finish, Idaho Sand & Gravel and its fleet of subcontractors were given 236 working days to complete the project. Idaho Sand & Gravel Co. (owned by Staker/Parson of Ogden, Utah) started doing construction work in the Boise Valley in 1972 as a small site contractor. The company is now one of the largest contractors in the state of Idaho. Washington Group International (Boise) served as the project engineer.

The project was finally awarded in December 2006 jointly by Ada County Highway District and Idaho Transportation Department. The bid award was delayed by almost two months amid issues related to utility movement and concerns expressed by local business owners related to impending traffic issues.

"For the most part, ACHD has handled the public involvement work," said Ryan Russell, project manager for Idaho Sand & Gravel. "But, we do hold a public meeting on-site right after our weekly subcontractor/utility meetings to answer any questions that the public might have."

Two Bridges

Work officially kicked off in January 2007 as roadway excavation began, along with the construction of the two prestressed concrete bridge structures — one over the Ridenbaugh Canal and the other over the Finch Lateral.

Prestressed concrete decks are commonly used for bridges with spans between 25 meters and 450 meters, providing economic, durable and aesthetic solutions in most situations where bridges are needed. Concrete remains the most common material for bridge construction around the world, and prestressed concrete is frequently the material of choice.

Maintaining traffic flow over the two bridges was a requirement of the contract, so the structures were constructed one half at a time. At the start of irrigation season in the spring, work was halted and work will be completed this fall when the irrigation season is over. The old structures will then be removed and the second section of the new structures will be built.

Even though they have created "hot issues," high temperatures and heavy traffic have not caused any major delays or safety problems. It's been the utility portion of the job that has continued to pose the major challenges. Regular communication and training has been effective in terms of addressing the safety of the crew and the public —related to extreme heat and traffic flow.

Unknown Dimension

Utility relocation and discovery has added an unknown dimension to the project because Maple Grove Road has provided numerous utility-related surprises from the start, which has posed major coordination challenges. Qwest Communications was the only significant player that relocated its utility (fiber optic lines) prior to the start of the project — a relocation that took place during the summer and fall of 2006.

"The contract states that utilities will require a 10-week window to complete their relocations," said Russell. "We are currently in our eighth month of utility impacts and, somehow, the project is still primarily on schedule."

Right out of the gate, 5,000 feet of new water main line had to be installed during the first four months of the year. The new line was installed while keeping the old water main in commission. The old line was in conflict with the new storm drains and the structures, which slowed the project. Power poles also had to be moved and communication fiber optic lines still unexpectedly continue to be found.

"It looks like spaghetti some days," added Russell. "There are 25 years-plus of utility placement on this road, and because many of the utility companies — especially communication companies — have changed hands over the years, there is sometimes little historical documentation of what was installed."

Generally, each utility company knows what it has in the ground and (for the most part) where it has facilities. Russell noted that the challenge has been to look at all the utility locations collectively to ensure that one utility relocation will not create a problem with another utility relocation.

"Just imagine fitting 10 different underground lines in an area the size of most people's backyard (everything from 4-inch to 24-inch size lines)," said Russell. "To add to the challenge, each utility type has certain requirements they must follow. For example, the water line must be at least 10 feet away from the sewer line when they are running parallel. Also realize that different utilities require different depths underground."

Waterlines typically are 4 feet below ground (or 4 feet of cover) and sewer lines are placed below waterlines, while maintaining certain separation requirements. The challenge is not just fitting them into a horizontal space, but also vertical planning.

"This is why we meet with all the utility companies weekly," added Russell. "We always have a new utilityissue/conflict to discuss."

Roadway Lowered

Excavation of the road took place, which included removing the original asphalt surface using a Cat 325 trackhoe. The contract required that the old asphalt be moved to ACHD's local pit where it's crushed and most likely used for road maintenance in the future.

The roadway grade for the most part is being lowered slightly and there is one area that required fill. A Topcon GPS electronic grade control system equipped with LazerZone is being utilized, which allows the grading work to being viewed in electronic form and ensures better efficiency and precision.

"We are placing subgrade geotextile as designed to ensure stability," said Russell. "The new roadway section includes 570 millimeters of granular subbase (4-inch minus gravel) and then 180 millimeters of 3/4-inch base gravel, and finally 135 millimeters of plant mix (asphalt)."

Russell noted that this is the first project for ACHD where recycled asphalt (RAP) has been used on a county road project. Out of the estimated 15,000 tons of asphalt required for the project, 10-percent RAP will be utilized. ITD's federal guidelines allowed this to happen on this particular project. Concrete Placing Company of Boise, one of the largest general contractors specializing in concrete paving and structures in the region, is providing over 7,100 cubic yards of the concrete on the total project

Approximately 3,500 linear feet of typical manhole-type storm drain pipe was installed during the excavation stage by Sommer Construction Inc. (Nampa, Idaho), the largest privately owned pipe contractor in Idaho. Stormwater drains to two detention ponds that were built with for this project, one at Emerald and one at Irving Street. Pipe size ranged from 300 millimeters to 900 millimeters.

"Sommer used multiple pieces of equipment during installation, including a Deere 450, Deere 330, Deere 225, Deere Loaders, Size 644 and 624," said Russell.

Two Intersections

At the time of publication, work on one the largest aspects of the project — the construction of one of two intersections — was under way. Both intersections are high traffic and among the busiest in the Treasure Valley. Shutting down traffic flow is not an option, so numerous strategies have been employed to keep cars moving. Under construction was the Emerald and Maple Grove Road intersection utilizing asphalt, and later in the summer the concrete-paved Fairview and Maple Grove Road intersection construction will take shape.

Because asphalt can withstand traffic on the same day it is placed, this first intersection was not as logistically difficult to plan as the second intersection. Concrete requires a seven-day cure period, so it will have to be staged much differently to allow traffic flow. The Fairview and Maple Grove intersection calls for concrete because it must handle more traffic, heavier loads and more durability related to traffic turn patterns.

One example of a strategy that has been employed to keep traffic flowing during construction has been the decision to use side dumping trailers at times. Side dumping trailers allow for the deposit of a load beside the truck. Stability problems are eliminated while dumping associated with the long end dump, and trucks are spared the need to run over the load as is required with a belly dump.

"It is becoming more common to build roads while maintaining traffic through the construction site, and this creates challenges," said Russell. "Access and work room is now limited, and side dump trucks are becoming more common for dumping material in tight areas where truck access is not possible. With a side dump truck, the driver can use existing roadways to drive up to the site them dump sideways into the work zone. We do not always use this configuration. Just in tight spots."

Other equipment employed for the Maple Grove Road project has included (but not limited to) a Cat 14H motor grader, a Cat 950 wheel loader, a SD110 Ingersoll Rand roller, a 4,000-gallon water tank, and a Rosco broom. Idaho Sand & Gravel owns most of its own equipment.

Upon completion, the new Maple Grove Road will provide much needed relief to ever-increasing traffic flow issues in the Treasure Valley.

"When the Maple Grove widening project is complete, there will be much more capacity on what was a congested route," said Craig Quintana, communications manager at the Ada County Highway District. "The improvements will result in a better, alternative route to the Boise Towne Square Mall and relieve traffic on Milwaukee. Significant traffic improvements will be seen at the Maple Grove, Fairview intersection portion of the project. That intersection has been a traffic choking point, particularly during the holidays."


Key Project Subcontractors

Specialty Construction Supply — Boise, Idaho (road construction supplies)

Qualitree Inc. — Nampa, Idaho (tree removal and trimming)

Concrete Placing Co. Inc. — Boise (concrete)

Ground-FX LLC — Boise (erosion control)

Hillside Landscape Construction Inc. — Nampa (landscaping)

MarCon Inc. — Meridian, Idaho (guardrails and precast)

Pavement Markings Northwest Inc. — Boise (pavement marking)

Power Plus Inc. — Boise (electrical)

Sommer Construction — Boise (underground utility)

Southfork Construction — Boise (guardrail)

Veasy Seeding Inc. — Meridian (seeding)

Golden West Advertising — Boise (signage)