The new cable-stayed bridge that straddles the Mississippi River between Cape Girardeau, Missouri and its sister city in Illinois is a remarkable structure, stretching for the length of 13 football fields over the famous waterway. After three years of construction, the bridge is finally nearing completion.
Two H-shaped towers, constructed of reinforced concrete, hold up 64 support cables each and extend 330 ft. (100 m) above the water. The cable strands are concealed by a white, high-density, polyethylene pipe and plastic sheathe. Altogether, the strands that make up the diagonal cables could span for 171 mi. (275 km), according to the Missouri Department of Transportation (MoDOT).
Construction of the Cape Girardeau Bridge, also called the Emerson Memorial Bridge, is estimated at $100 million. Eighty percent of the funding comes from the federal government. The other 20 percent of the cost is split between Missouri and Illinois.
The design of the bridge began in 1996 but major construction did not start until June 2000, when MoDOT awarded a contract Evansville, IN’s Traylor Bros. Inc., one of the foremost bridge contractors in the world.
The MoDOT contracted Traylor Bros. to:
• complete Pier 2
• construct Piers 3 and 4
• install 128 stay cables
• construct the bridge deck on the main bridge and the Illinois approach bridge, and
• install 140 decorative lights
Substructure work included two dredged caissons and two 364-ft-tall (111 m) main pylons. Superstructure work included installation of the stay cables, 8 million pounds of structural steel and an 11-in.-thick (28 cm) precast concrete deck with 3-in.-thick (7.6 cm) poured-in-place micro silica fume overlay concrete.
Traylor Bros. expects to be done with the project by late 2003, said Larry Owens, project manager.
Traylor Bros. was organized in 1946 and, over the past 50 years, has proven its ability to construct almost anything above ground or below, on land or water, of concrete or steel. Traylor Bros. has completed more than 130 major bridge projects, including some of the largest and most complex bridge projects in the world.
Engineering News-Record (ENR) ranked Traylor Bros. 18th out of the Top 25 Bridge Contractors in its 2003 Sourcebook. ENR also listed Traylor Bros. among the “Top 100 Contractors By New Contracts” in May.
The suspended four-lane highway is 96 ft. (29 m) wide, and rises 60 ft. (18 m) above the Mississippi. The deck is composed of steel plate girders and floor beams and pre-stressed concrete slabs. A concrete barrier is located in the center of the bridge, and two concrete railings are placed along the edges of the deck.
The overall weight of the bridge is 266 million lbs. — equal to the weight of 304 jet airplanes. Crews are using an estimated 13 million lbs. of reinforcing steel and 243.6 million lbs. of concrete to build the bridge.
Annual Status Reports
By summer 2001, Traylor Bros. had finished the dredged caisson for the Illinois-side pylon despite some nasty winter weather in late 2000 and early 2001, and one minor challenge: driving the caisson the last 10 ft.
In order to force the caisson to sink the final distance, a blasting subcontractor was hired to set off explosive charges that shook it down. A total of 58 rounds were needed to complete the job. After the caisson was landed and the bottom cleaning was finished, it was a mad rush against a rapidly rising river to get the tremie seal concrete poured.
On Friday, June 1, 2001, the crew received a forecast that predicted the river to rise above flood stage early the next week. Traylor Bros. decided to begin the tremie pour the next morning and pour through the weekend in an effort to beat the flood. Two crews traded 12-hour shifts to complete the 4,700-cu.-yd. (3,593 cu m) pour by early Monday morning.
MoDOT reported it to be its largest concrete pour on record. Shortly after the record-breaking pour, the river flooded. As it turned out, if Traylor Bros. had not pushed through the alternating 12-hour shifts, the crew would’ve been delayed by about eight weeks.
By the summer of 2002, the 350-ft.(106 m) Missouri pylon was complete and the crew was focusing on the Illinois pylon, which was well along. Work also was progressing on the Illinois back pier. Several pours were finished, including a 1,900-cu.-yd. (1,452 cu m) distribution block concrete pour and six-stem pours, ranging from 750 cu. yds. (573 cu m) to 1,200 cu. yds. (917 cu m).
Eleven of the 30 tower leg pours for the Illinois pylon, averaging 80 cu. yds. (61 cu m) each, were done, and the follower and sand island cofferdams for that pier had been removed.
By spring 2003, construction of the 356-ft. (108 m) main pylon in the center of the river was complete. Stem construction for the Illinois back pier also was complete, and 16 of the 64 stay cables for the Illinois pylon were installed. Rebar installation and deck concrete placement on the Illinois approach bridge was in progress and superstructure erection of the Missouri pylon was well underway. All stay cables were in place by August.
Owens said superstructure finish work, overlay, barrier walls, and cable grouting should be complete by the end of the year.
The Role of Rental Equipment
Rental Equipment from RSC, one of three brands belonging to Rental Service Corp., North America’s second largest equipment rental company, played a vital role during construction of the bridge. Traylor Bros. has rented a variety of equipment from the local RSC stores since December 2000 — everything from mini-excavators, skid steer loaders and air compressors to variable reach forklifts, pressure washers, brush chippers and diaphragm pumps.
Owens said Traylor Bros. prefers to own its own equipment but occasionally needs to rent equipment when there isn’t a company-owned machine available — or when it is more cost effective to rent equipment than to transport a Traylor Bros. piece to the job site. Owens said Traylor Bros. also rents if a piece of equipment is only needed for short-term use, or if a unique size or capability is required.
In the case of the Cape Girardeau Bridge, Traylor Bros. rented several items from RSC, including several 120-ft. (36 m) boom lifts, a ride-on broom and half a dozen light towers. Since not all of the equipment was on-site at the Cape Girardeau RSC store, Branch Manager Gerald Wachter had to work extra hard in some instances to meet the time demands of the job, Kraemer said, shipping in equipment from multiple RSC locations on an as-needed basis, in time to meet Traylor Bros.’ needs.
Owens said his crew used the boom lifts from RSC for access when performing miscellaneous tasks like concrete patching, form stripping, steel bolt ups, etc. The broom was used to quickly and efficiently clean up the bridge deck, he said, and the light towers were used for night work.
Kathy Kraemer, territory manager for RSC, said it was been a breeze working with Traylor Bros.
“They always know exactly what they need and when they need it. It really makes our job easy,” she said. “They have done some 18- to 24-hour pours — even two 48-hour pours. Needless to say, the light towers have played a vital role at times.”
Kraemer said RSC effectively used a “team approach” to meet Traylor Bros.’ needs.
“We made sure that all of the Traylor Bros. personnel involved with rental were introduced to and knew our entire team by name — all of the counter sales team, the store manager, the truck drivers and the mechanics, in addition to Tom King, the other sales rep on the job, and me,” she said.
“It was such a big job that everyone really had to pull together to meet the demands of this customer. Drivers came in early mechanics stayed late, and counter sales made dozens of calls … I can’t emphasize enough how important the entire team was in meeting Traylor Bros. rental needs.”
History of the Bill Emerson Memorial Bridge
Cape Girardeau has evolved over the past 200 years from the tiny French trading post it was in 1733, to a community of nearly 40,000 residents on the world’s only inland cape. The Bill Emerson Memorial Bridge replaces a bridge built in 1927 and is expected to handle the increased traffic flow in the area.
The bridge is named for the late eight-term Southeast Missouri congressman who helped lead efforts to secure funding for its construction. Emerson worked hard to secure Federal Highway Administration money to proceed with the construction. He passed away in June 1996, shortly before the contract to build the bridge was awarded.
An estimated 14,000 vehicles cross the bridge daily. By the year 2015, the Missouri Department of Transportation estimates, about 26,000 vehicles will cross the bridge each day
In mid-August, cranes on barges lowered two 3,700-lb. (1,678 kg), 6-ft.-long (1.8 m) steel girders in place to close the gap.
As of September, all the deck panels have been put on, the cables have been adjusted, and a 3-in. (7.6 cm) concrete surface has been poured across the length of the span. Then, concrete barrier walls and electrical work have to be done and decorative lighting added. In addition, grout must be pumped between the polyethylene casing and plastic sheathing that covers the steel cables.
“The grout work won’t happen until the end of the project, and it can’t be done when the temperature is below 45 degree,” Owens said.
After the last of the pre-cast deck panels was erected, a 3-in. (7.6 cm) driving surface to the cable-stay portion of the bridge was installed. Traylor Bros. used special concrete containing silica fume, a byproduct of silicon metal. Concrete containing silica fume is highly impermeable and has an estimated life of 50 years.
The temperature can’t exceed 85 degrees or dip beneath 40 degrees while the special concrete is applied.
Owens said if the weather cooperates, the bridge should be open to motorists by late 2003. CEG
(April Goodwin is a technical writer in Des Moines, IA)