By: Rick Zettler
A key principle behind last year’s economic stimulus program was to give a shot in the arm to the construction industry by investing in infrastructure rebuilding.
With the program winding down, the industry has seen mixed results. Construction unemployment hovers around 20%, while many argue over just how much new money is actually getting pumped into infrastructure. However, there are several examples of the economic stimulus program working as designed. The nearly completed Tulsa Inner Dispersal Loop (IDL) around downtown—the largest single project in the history of the Oklahoma Department of Transportation (ODOT) and largest stimulus-funded project in the U.S. at the time of its letting—is a prime example of the substantial progress that can be accomplished with an infusion of cash to the states. “Ninety-five percent of this project is stimulus funded,” said Travis Smith, resident manager, Tulsa Residency for ODOT. “This project was expedited by at least five years on the plan, and we never would have been able to let this as a single project without the stimulus money.”
Initiated in June 2009, the $75 million project encompasses reconstruction of all lanes of the west and north loop segments of I-244 around downtown Tulsa and some surface repair to the other loop segments.
“It was an A-plus-B contract where we bid a base (A) of approximately $67.6 million and then bid $15,000 a day (B) for the 540-day contract,” explained Wesley Seabolt, project executive for Manhattan Road & Bridge, Tulsa.
Even with Manhattan Road and Bridge’s 50-plus years of experience building bridges in markets reaching from Oklahoma to Louisiana, a project this size required a joint venture. The company is in a 60/40% joint venture with Sherwood Construction Co. of Wichita, Kan., where Manhattan Road and Bridge is responsible for nearly 80% of the project’s bridge work. Sherwood is handling the surveying, grading and removal and repaving of the IDL’s roadways as well as the remainder of the bridge work.
Working the skews
The most critical work for the IDL centered on bridge reconstruction and paving. The north and west segments include 44 bridges that require significant repair.
“A majority of the bridges are rated as structurally deficient,” commented Smith.
Reed Wood, general superintendent for Manhattan Road and Bridge, added, “Every bridge required removal of the deck to the top of the beams, and we fixed some of the substructure on those in worse condition.”
Throughout the U.S. more than 30% of the total bridge deck area is structurally deficient, and the average bridge age is 43 years. The bridges along Tulsa’s IDL closely mirror this national statistic. With most of the bridges built in the 1960s, “the roadway and bridges were in rough condition and needed replacing,” said Seabolt.
“On an NBI [National Bridge Inventory] rating of 0 to 10, with 4 being structurally deficient, a majority of the bridges on the IDL were rated at 4 or less,” added Smith.
The contract included two 200-day milestones for bridge work completion or Manhattan Road and Bridge faced a $20,000 per day disincentive for missing the deadlines. With so much riding on the bridge work, everything from material delivery to paver length and options had to be meticulously planned. Even with careful planning, material delays have been encountered. After going through all the bridge specs, the contractor noticed the designs presented multiple challenges for the crews and bridge pavers. Several of the decks transitioned from a left slope to a crown to a right slope. Others had a continuous span that had to be poured by skipping segments so as not to overload the deck beams. Fifteen of the decks flared out from one end to the other more than 15 ft. “One deck measured 16 ft wider from one end to the other, and the total bridge length was only 150 ft,” recalled Wood. Nearly half of the bridges were designed at a skew angle, which required machine length to be significantly wider than bridge width at square, so the paver can pave the crown at the skew angle to get the proper finish. With some of the skew angles as high as 50°, Manhattan Road and Bridge purchased a skew bar kit.
With bridge widths and skew angles dictating machine widths ranging from 36 to 120 ft, a Terex Bid-Well 4800 paver was used for the project. With its 48-in. truss depth, the paver is capable of paving widths from 36 to 172 ft without deflection. The 18-ft end segments of the 4800 offer up to 15 ft of leg travel to each side to handle bridge width flares. The new paver also complements the three other Terex Bid-Well pavers working on the project.
90% effective
Currently, Manhattan Road and Bridge has completed more than 90% of the 7 lane-miles of bridges on Tulsa’s IDL. Bridge Work Phase 1, completed on schedule in May 2010, saw Manhattan Road and Bridge’s crews finishing 20 bridges on the westbound section of the north loop segment and southbound lanes of the west segment. These lanes are now open, while the northbound and eastbound lanes of the west and north segments, respectively, are being reconstructed.
Manhattan Road and Bridge is using a 4,000-psi concrete to pour the 8-in. deck thicknesses. The mix has a 3-in. slump, but the producer is using a water-reducing agent to increase slump to 5 to 7 in., since it is being pumped to the deck from ground level. “The retardant helps to reduce segregation and keeps a low water-to-cement ratio while maintaining workability,” explained Wood.
Nearly complete with the second half of the contract, Manhattan paved some of the more complex bridge designs during Phase II of the project. In August, crews completed a series of pours on Bridge 52, a long continuous-span bridge that flares from 53 to 65 ft end to end. From south to north, the deck also twists from a 3.2% left slope to being flat with a crown at the center to a 6.2% right slope. Due to bridge design, crews first poured the center section and skipped sequence pours to maintain proper beam loads. At the time, beating the heat seemed to be the biggest obstacle for the paving crews. Multiple segments of this bridge were poured during a time when daytime temperatures reached 105°F, and nighttime readings only retreated to the 80s.
“We must keep the concrete below 90°[F], so we poured in the early morning hours and ended by 9 a.m.,” recalled Wood.
To aid in maintaining a lower temperature, Manhattan Road and Bridge equipped the Terex 4800 paver with an optional fogging system. Attaching to the finish pans, this system produces a true light fog to aid in finishing the concrete.
Bridge 53 also challenged the expertise of the paving crew. At 1,050 ft long, bridge paving began with a flat grade and 2-ft crown. At a distance of only 300 ft from the header, this crown expanded to almost a lane width. “I recommended that we add a longitudinal joint from the abutment to Pier 2 as a solution,” said Eben [Identify!]. From Pier 2 to the opposite end, paving crews had to narrow the paver from a 63 ft width down to 51 ft. Yet even with all the bridge-design intricacies, Manhattan Road and Bridge has continued to rise to the challenge and pour extremely smooth decks, while remaining on target to beat the contract deadline and receive the full bonus.
The true winners are the 62,000 motorists daily traveling the north and west sections of the IDL. With a single contract, many lane-miles of roadway and structurally deficient bridges are being brought up to modern-day standards, increasing safety. “It’s been a privilege to be a part of this project,” concluded Smith.
About The Author: Zettler is with Z-Comm, Cedar Rapids, Iowa.
