Challenge
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 14.2 mile 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.
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 the longest bridge specifically designed and constructed for pedestrians and bicycles.
The new bridge will be 3,463 linear feet long, elevated 65 feet above the navigation channel, with 653 feet of walled embankments. It will feature a 14-foot 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 dates. 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 would be anchored to the dam.
Bluegrass operators began core drilling five intersecting holes for wire access. They drilled two 3-inch-diameter holes, 13 feet deep, from the top of the pier and then drilled two horizontal, 3-inch-diameter holes from the fact 8 feet deep. Them, drilling from the side of the concrete pier, they intersected all the holes with a 6-inch-diameter, 5-foot-long 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 3-1/2 inch-diameter, 10-foot-deep holes into a diamond shape.
To ensure job safety, operators performed a thorough pre-site check and evaluation and wore the appropriate Personal Protective Equipment (PPE).
The river’s high water levels forced operations to shut own 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 cubic yards of concrete. The sawing and drilling operation took two full months with six operators on the job, and the project was finished on time.
Process
Outcome
“We developed our strategy and our technicians did what they always do – worked hard and efficiently performed the task to the contractor’s praise,” said Bluegrass who won the job due to 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.” “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-mile 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.