Mobley Contractors Inc.? photo
“Project one is the box culvert, while project two is the overpass and elevated roundabout at Amity and Elsinger,” said Jack Branscum, city of Conway, street and engineering department.
Motorists in Conway, Ark., are dealing with lane closings, as construction of a bridge over Interstate 40 continues. The work, a partnership between the city of Conway and the Arkansas Highway and Transportation Department (AHTD), is tied to a nearby major development, and is one of five different projects included in an overall improvement plan.
“Project one is the box culvert, while project two is the overpass and elevated roundabout at Amity and Elsinger,” said Jack Branscum, city of Conway, street and engineering department. “Project three is the roadway improvements for Bruce Street and 6th Street. Project four is the Oak Street improvements and north portion of Central Landing Boulevard, while project five is the south portion of Central Landing Boulevard.
The approximate start for the bridge and elevated roundabout was mid-2015, with an expected finish of fall 2016. The bridge is located at mi. marker 128.
The project was designed, in part, to alleviate congestion.
“The bridge is meant to connect 6th Street to Elsinger Boulevard,” Branscum said. “It will also help relieve traffic on Oak Street, by providing an alternate east-west corridor.”
There also is a new road, known as Central Landing Boulevard, being constructed to give direct access from Oak Street/Highway 64 to the Central Landing development.
The city of Conway is funding 100 percent of the cost and administering the project, with AHTD oversight. Branscum said the time was right to build.
“Conway just recently built a new airport on the edge of town. With several acres of land in the middle of town ready to be redeveloped, the citizens of Conway saw the opportunity and passed a bond to invest in the new infrastructure, in order to get the most return out of this old airport as possible. There was a lot of planning involved,” Branscum said.
The existing box culvert was in the way of the bridge, so a new box culvert was needed to allow the appropriate space for the bridge, according to Branscum.
The area of interstate serves 48,000 vehicles per day.
Motorists are being cautioned to stay alert, especially in construction zones. A temporary road will be built connecting Elsinger and Amity to detour traffic around the roundabout.
Manhattan Road and Bridge is responsible for the 6th Street I-40 overpass construction. Manhattan Road and Bridge project manager Denis Guilette said the main concerns for his crew involve performing tasks over I-40, as well as protecting the traveling public and all workers.
Construction began in August 2015 and should be completed by November 2016.
“Currently, we are building the west approach and bridge substructure,” Guilette said. “We have placed 30,000 yards of fill to date, and started the west abutment and retaining wall.”
A total of 130,000 cu. yds. (99,392.1 cu m) of dirt is being moved on the job, which also includes 1,200 cu. yds. (917.4 cu m) of concrete and four pre-cast mechanically stabilized retaining walls. Two of the walls are associated with the bridge abutments, the others are for the roundabout, which is 100 ft. (30.4 m) in diameter, with a 10-ft. (3 m) wide inside truck apron.
Specific work on the overpass will involve the construction of three support bents, one in the median and the erection of steel over I-40. The roundabout calls for 75,000 cu. yds. (57,341.6 cu m) of fill to raise the road 17 ft. (5.1 m) above existing conditions.
Equipment being used on the overpass project includes a Link-Belt LS-138 crane, a Terex HC80, a Cat D6 dozer, two articulated dump trucks, vibratory rollers and a grader for finishing.
Utility relocation work and construction being done by other contractors has led to setbacks, although weather has not been a factor, so far.
“We started on the project during the summer and lately have had pretty good conditions. We’re about where we thought we would be.”
Guilette said minimal clearing was needed at the existing location, the old Conway airport, which connects to a retail and restaurant area. The most time-consuming part of the work involves construction on the retaining walls that border a nearby shopping parking lot and steakhouse.
“They’re needed to support the grade raise for the roundabout. They are 400 feet long a piece, and we have to build in conjunction with the embankment, said Guilette.”
“The bridge is 214 feet long. It has 16-foot pedestrian sidewalks with planters for landscaping. Architectural features include a stone finish on the exterior, exposed concrete surfaces, with a dark brown and tan paint scheme. The structural steel and pedestrian handrail will be painted jet black.”
According to Guilette, the project is going as expected.
“The city has been good to work with. We just want to complete everything, and not impact local businesses and the traveling public.”
The general contractor for the box culvert is Mobley Contractors Inc.
Brad Deaver, Mobley Contractors project manager said Mobley is self- performing the majority of the work on this project, including site prep, clearing and grubbing, unclassified excavation, embankment, backfill, concrete barrier wall, reinforced concrete pipe, a double 11 by 6 ft. (3.3 by 1.8 m) concrete box culvert, stone backfill, course aggregate and riprap. Asphalt work is done by a subcontractor.
“The biggest challenge has been coordination with municipalities and contractors working in the same location. This is a relatively small construction site. Underground and overhead utility relocations have been a major delay on this project,” said Deaver.
“This phase began on June 22, and we hope to finish by Thanksgiving. We have completed 60 percent of box construction. The detour road is almost complete. This will allow us to move traffic and complete the remaining 40 percent of the box culvert.”
Approximately 500 ft. (152.4 m) of box has already been built. A total of 5,080 cu. yds. (3,883.9 cu m) of excavation has been hauled out and 3,444 cu. yds. (2,633.1 cu m) of fill dirt brought in.
“The next major milestone is to move traffic onto the detour road, which will allow us to complete the remaining portion of the box culvert. Box culvert work requires water flow diversion or pumping, excavation for the new box culvert, placement of rock subgrade for the bottom concrete slab, formwork, reinforcing steel installation, concrete placement and dirt backfill of the newly constructed box,” said Deaver.
Deaver said the biggest challenge regarding drainage work is moving the existing channel flow by diversion ditches or bypass pumping to allow a dry place to work.
“Our job does not go under the interstate. We are attaching to a box already running underneath I-40. Detour road work consists of excavation to a desired elevation, subgrade preparation, class ’seven’ rock fill, asphalt placement and striping.”
Battling the elements has also been an issue, although not lately.
“Every time we have a rain event, our site floods because we are working in an existing channel,” Deaver said. “We are currently in a very dry time of year that has helped construction.”
Some minor tree clearing along I-40 was required for the box construction, which typically consists of three pours involving the bottom, walls and top. For this assignment, crews are constructing a box using a special two-pour method.
“We place the bottom slab in one pour and then pour the top and walls together. This requires a special forming system, but allows us to reduce our construction time and speed up the job,” Deaver said.
Equipment being used on the box culvert job includes a Manitowoc 222 100-ton (90.7 t) crane to move all the materials for the box construction, Link-Belt 460 and Link-Belt 135 excavators, a Cat D5 bulldozer, compactors and a Cat 416 backhoe. Materials include 700 tons (635 t) of aggregate base course, 175 tons (158 t) of asphalt binder course, 175 tons (158 t) of asphalt surface course, 1,433 linear ft. (436.7 m) of precast concrete barrier wall, 250 linear ft. (76.2 m) of reinforced concrete pipe and 900 linear ft. (274 m) of a double 11 by 6 ft. reinforced concrete box, amounting to 2,417 cu. yds. (1,847 cu m) of concrete.
The cost of constructing the overpass is $9.7 million, with a price of $1.5 million for the new box culvert. Five million is being spent on the Oak Street improvement project, with the cost of Bruce Street 6th Street improvements totaling $3.5 million. Work on the south portion of Central Landing Boulevard just over half a million dollars.
According to Jamie Gates, executive vice-president of Conway Development Corporation, “The I-40 bridge project will connect our largest shopping center, Conway Commons, with a planned 150-acre development called ’Central Landing.’ We’re obviously excited about linking these two projects. We are also providing an additional east/west connector. Having I-40 bisect the city has made that a historical challenge.”
Central Landing, with roughly 300,000 sq. ft. (27,870 cu m) of retail and dining, started construction this summer at the site of the old Conway Municipal Airport. Gates said the overpass will serve two audiences, including local residents heading to Conway Commons.
“That overpass will be the preferred route, as it will keep them off a very crowded Oak Street [Highway 64]. Second, it will serve any shopper who wants to bounce back and forth between Conway Commons and Central Landing. We will have a truly regional shopping destination, and the bridge will put the two developments seconds from each other.”
“Taking local traffic destined for Conway Commons off Oak Street helps everybody,” said Gates.
Redeveloping land in the middle of town is significant in more ways than one.
“Conway is a growing community, so it’s rare to find undeveloped property in the city center, especially property that has interstate visibility. It’s a historic opportunity that came from relocating our airport,” said Gates”
“The need for additional east/west connectors was identified in a 2010 community-wide planning effort called Conway2025. The development of Central Landing and relocation of our airport accelerated the timeline. The project has a lot of moving parts. Thankfully, they’re all coordinating well.”
As for the design elements, “The bridge is being built to a design standard that the Conway Chamber established with the help of a local engineering firm. As the I-40 corridor has redeveloped with a recent widening project, we’ve had the opportunity to do things with bridge design, architecture and color that hopefully help us stand out in a good way. This bridge will also feature large planters, trees, and accommodations for pedestrians and cyclists.”
The overpass is funded with a local bond issue. Gates said the project has been in the making for a long time.
“We’ve worked a number of public projects here, and it’s always nice to see them underway. I think the best thing about the construction is seeing the impact it has on business. Now that folks see the work underway, the entrepreneurial juices are flowing. There’s a lot of interest in the real estate. I think sometimes it takes seeing some dirt move before people take projects seriously.”
Gates also said working with AHTD has been seamless.
“Our community has never had a better relationship with AHTD. They’ve been great to recognize private sector timelines and sensitivities. We think Conway is a progressive place with regards to design and engineering, and AHTD has allowed us to build accordingly. It’s a valued and important relationship.”
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