The Two Rivers Bridge opened in July 2011 and sits above the Little Maumelle River, connecting miles of trails in Pulaski County, Arkansas. At the highest point, the bridge deck is approximately 45 feet above the river's normal pool level. It is 1,162 feet long and is part of a 2,300-foot improvement project that includes ramps and trail connections.
Central Arkansas engineering firm Garver provided structural, electrical and site design and environmental services on the project. Engineers and surveyors spent more than 4,000 hours from concept to completion to ensure that the $5.3 million pedestrian and bicycle bridge will be enjoyed by outdoor enthusiasts for years to come. This is the fourth pedestrian bridge along the trail system that bears Garver's engineering stamp—Garver also designed the Big Dam Bridge attached to the Murray Lock and Dam and bridges across the White Oak and Shilcott bayous.
Garver designed the 210-foot steel truss navigational span to meet U.S. Coast Guard requirements. The prefabricated, parallel chord steel truss was manufactured in Alabama and shipped to Arkansas in eight pieces. After being assembled on site, two cranes floating on barges lifted the 200,000-pound truss onto hammerhead piers. Because the lifting weight approached the cranes' capacity, the handrail and deck stringers were left off the truss and installed once the unit was set in place. The final truss weight is approximately 500,000 pounds. After assembly was complete, new navigational lighting systems were installed.
The truss span sits on 7-foot-diameter columns and 8.5-foot-diameter drilled shafts. The columns and shafts are designed to withstand a 215,000-pound force from a vessel collision. The piers are constructed on drilled shaft foundations as much as 96 feet deep.
The remaining portions of the 13-span bridge utilize prestressed concrete girders. Concrete girders were less expensive than a steel beam option and better mitigate vibrations when cyclists and pedestrians cross the bridge. Approximately 550 cubic yards of concrete and 115,000 pounds of reinforcing steel were used to construct the superstructure.
Low-profile LED fixtures provide safety and security lighting along the bridge pathway. These pole-mounted fixtures are "dark sky" compliant products, which eliminate upward light spillage, and they also feature the latest LED technology to reduce energy and maintenance costs.
In addition, an LED aesthetic lighting system uses state-of-the-art linear "wall-wash" LED fixtures to illuminate the exterior bridge fascia. These linear light fixtures are mounted along the bottom of the deck overhang and the truss' bottom chord. The LED fixtures are capable of 16.7 million color combinations, and the programmable control system can display multiple color light shows similar to the Big Dam Bridge.
The trail additions are 12 feet wide with 3-foot shoulders. The asphalt parking lot contains 70 vehicle spaces, and Garver designed the pavement to shed water into grass swales and then travel to a detention pond. This helps reduce the amount of discharge and pollutants that leave the site.
In July, U.S. Secretary of Transportation Ray LaHood was on hand for the bridge's ribbon cutting—which appropriately featured bicycle tubes wrapped in red ribbon. "Thank you for what you're doing, providing people an opportunity to exercise, to experience the great outdoors, to experience this great part of the country," LaHood said. "This is a great project."
The bicycle community has lost no time adding the Two Rivers Bridge to its various rides and races. The Big Dam Bridge 100 bike ride now includes the new bridge in its 100-mile course.