The Arkansas River Trail, also known as the Millennium Trail, is an extensive network of paved pedestrian pathways extending northwest from downtown Little Rock and skirting both shores of the Arkansas River. When completed, the Arkansas River Trail will reach from downtown Little Rock to Pinnacle Mountain State Park on the southern shore, and from downtown North Little Rock to Cook’s Landing on the northern shore. More than 24 mi. (38.6 km) of trails have been proposed and nearly 14 mi. (22.5 km) are complete.
A final link in the loop connecting Little Rock and North Little Rock is the Pulaski County Pedestrian and Bicycle Bridge over the Murray Lock and Dam. Now under construction, this bridge will be longest bridge specifically designed and constructed for pedestrians and bicycles.
The new bridge will be of 3,463 lineal ft. (1,055 m) long elevated 65 ft. (20 m) above the navigation channel with 653 ft. (199 m) of walled embankments. It will feature a 14-ft. (4.3 m) wide deck capable of handling pedestrian and bicycle traffic. The deck is being constructed with weathering steel girders to minimize future maintenance and it is being built with gentle slopes to assure compliance with Uniform Federal Accessibility Standards.
Plans called for the Murray Lock and Dam to serve as the foundation for the new bridge but it was determined that the Murray Dam could not accommodate additional supports on top as they would interfere with the operation of the gates. Instead, engineers decided to drill shafts into the existing 14 sloped piers on the downstream side of the dam. Rock bolts would then be installed into the piers so that the new bridge columns could be anchored to the dam.
In Spring 2005, general contractor Jensen Construction of Sand Springs, OK, hired CSDA contractor Bluegrass Concrete Cutting, Inc. of Greenville, AL, to perform the sawing and drilling needed to create the shafts as well as to drill the core holes for the anchors. Bluegrass determined that wire sawing would be the quickest, least destructive and most cost-effective method for removing the concrete segments and set to work.
Bluegrass operators began core drilling five intersecting holes for wire access. They drilled two 3-in.-diameter (7.6 cm) holes 13 ft. (4 m) deep from the top of the pier and then drilled two horizontal 3-in.-diameter (7.6 cm) holes from the face 8 ft. (2.4 m) deep. Then, drilling from the side of the concrete pier, they intersected all of the holes with a 6-in.-diameter (15.2 cm), 5-ft.-long (1.5 m) horizontal hole. Operators then wire sawed the concrete section loose from the pier. Then they made a mid-horizontal cut to divide the section into two blocks for rigging and removal.
Working inside the newly-created pocket, Bluegrass operators core drilled a series of holes for the installation of rock bolts. In each of the 14 piers, they drilled 16 3.5-in.-diameter (8.9 cm), 10-ft.-deep (3 m) holes in a diamond shape.
To ensure job safety, operators performed a thorough pre-site check and evaluation. They wore all the appropriate Personal Protective Equipment (PPE) and were tied off to the work platforms at all times.
The river’s high water levels forced operations to shut down for several weeks, but otherwise the job progressed smoothly. In all, Bluegrass operators drilled nearly 300 core holes and hollowed out 14 piers, removing 121 cu. yds. (92.5 cm m) of concrete. The sawing and drilling operation took two full months with six operators on the job and the project was finished on time.
“We developed our strategy and our technicians did what they always do — got to the job site, worked hard, worked efficiently and performed the task to the contractor’s praise,” said Tony Niehaus, Bluegrass vice president. He said he believes Bluegrass won the job because of their experience performing this type of work over the past 27 years.
“We know everything there is to know about wire sawing and can provide solutions for the easiest job to the most complicated,” Niehaus said. “They remember our name because we save them time and money.”
The Pulaski County Pedestrian and Bicycle Bridge is slated for completion in Fall 2006 and city leaders are eagerly awaiting the completion of the 14-mi. (22.5 km) loop hoping it will draw more residents and visitors to the growing downtown and riverfront areas. Little Rock and North Little Rock residents who use the trail are looking forward to using the new connection and enjoying the city from their new vantage point.
Bluegrass Concrete Cutting Inc. of Greenville, AL, performs specialized concrete and metal demolition services worldwide. The company offers services in several areas of selective demolition including consulting, construction engineering, project management, diamond wire sawing, core drilling, concrete contamination shaving and robotic hammering. Bluegrass also has substantial nuclear experience including fast-track shutdowns, fossil power, petrochemical and steel renovations. They operate 30 diamond wire saws and 25 robots. Bluegrass attributes their success to a dedicated management team and their 25 highly skilled demolition technicians, 20 of which have extensive nuclear experience and 21 of which have 40-hour hazwoper training. Bluegrass has been in business since 1979 and has been a member of CSDA since May 2005.
For more information, visit www.swl.usace.army.mil/projmgt/pulaskibridge.html.
(Reprinted courtesy of the Concrete Sawing and Drilling Association, Concrete Openings magazine, March 2006.) CEG