You could say that Mesquite is creating a bit of state history with the West Mesquite I-15 Exit 120 Interchange project. It's the first time a new construction method for building road bridges is being used in Nevada.
Alan Preston, Project Manager for the construction contractor, W.W. Clyde, explained the bridge construction process process his company is using at a Public Information Meeting hosted by the Nevada Department of Transportation Thursday, Nov. 3, at Mesquite City Hall. "It's called ABC, short for Accelerated Bridge Construction," Preston said.
"We are building the bridges right now, on-site. This past Tuesday night we placed five girders across Falcon Ridge Parkway on the I-15 southbound side. The whole bridge will be built on-site and then we'll slide it into place," Preston said. "We'll place the girders for the I-15 northbound lanes Friday night [Nov. 4]."
If he makes it sound so easy, that may be because Preston has done it before on several construction projects with W.W. Clyde in the Salt Lake City, UT, area. But, it's really a fascinating process that requires a lot of juggling and a lot of work.
(Click here to access a diagram of the bridge construction.)
"On Monday, Jan. 10, barring any unforeseen glitches, we're going to close Falcon Ridge Parkway completely. We'll divert the I-15 southbound traffic off the regular road and have it go down the off-ramp and back up the on-ramp lanes. We're building a second travel lane on those ramps now so we'll have a continuous, non-stop flow of traffic on I-15," Preston said as he continued his explanation of the process.
"Once we've closed the regular interstate lanes, we'll tear out the old bridge on the southbound lanes by Tuesday. Then Tuesday night we'll slide the new bridge into place. On that Wednesday we'll lay the asphalt to tie it to the existing road. Then on that Thursday before 5:00 am we'll open the interstate lanes back up for regular traffic. The whole process will take 56 hours. And, it will be a busy 56 hours," he remarked. "After that, we all go sleep for two days."
(Click here to access the six phases of the bridge slide)
Preston explained that moving the new bridge into place is "a little like watching grass grow, but don't blink or it's over. It takes about two to three hours for the actual slide, but while you're watching it, it seems much slower."
"There are specially made Teflon pads that are built right into the bridge," Preston continued. "There are also Teflon pads built into the area where the bridge will eventually sit. We use a lubricant that helps the slide. It's actually dish soap."
There's been so much interest in the process that the company and NDOT have actually planned out a viewing place for the public to watch the process. "We will set up an area behind Wal-Mart for the public to come and watch us do this if they
want," Preston commented. "We don't want anyone to take chances within the construction site but we want to give them a safe place to watch."
(Click here to access the planned viewing areas for the bridge slide.)
"We've been putting in the 'soil wall' that everyone has seen. Then we drove 'piles' into the ground anywhere from 25 feet deep to 50 feet deep next to where the permanent bridge will be located. Those are just temporary supports to build the new bridge on. Then we put the girders in which is what we're doing this week," Preston continued.
"Once we get that done, we'll pour the concrete on top of the girders and finish off the bridge. While all that is being done, we're pouring new footings and new abutments under the existing bridges that the new bridge will slide onto.
"The only place that bad weather will affect us is tying in the asphalt on the interstate roads. If we have a really bad cold spell we may have to delay it," he commented. "We expect to be finished with the whole project by May and open it to the public."
"It's a fun project," Preston said. "We've had a great team with NDOT. That makes it fun to come to work."
If W.W. Clyde finishes the project before the 12 month deadline in June, they'll receive a $400,000 bonus. If the project runs late however, the company will be fined $10,000 a day.
Greg Graham, Landscape Architect with EDA Land Planning, explained the new landscaping that will accompany the project.
"We are excited about the new look the interchange will have because it will add character to the City's entrance. The colors we're using are repeated in other places in Mesquite so it will all tie together," Graham explained.
(Click here to access a diagram of the wall landscaping.)
Explaining the 'design-build' concept being used for the whole project, Graham said, "As the architects finish with the design, the construction workers immediately start working on it. They know what needs to be designed first. That gets put into place and they start designing the next part. The design professionals work hand-in-hand with the contractor and the State to get it done. It's really a fun and fascinating process."
"We helped design the texturing on the walls of the project and the monuments in the center of the roundabouts. Some of the pieces are actually being constructed now. They are on a fast track with the ABC process," Graham remarked.
(Click here to access a diagram of the roundabout monuments and landscaping.)
He added that the soil areas around the new interchange will be seeded with native grass plants that won't require special irrigation. "The only irrigation we'll need is for the palms trees in the center of the roundabouts. We're going to let Mother Nature take her course and let the plants develop on their own."
(Click here to access a diagram of the landscape materials.)
[Editor's note: The PDF files made available in this article are the actual display diagrams used in the NDOT Public Information Meeting.]