Repairs should add seven to 10 years of additional life to the bridge depending on severity of upcoming winters.
Contractors are familiar with projects that turn out to be more than they bargained for.
That’s the kind of project structural repairs to the Missouri River Bridge at State Route 47 became for Patrick Dolan. His company, St. Louis Bridge Construction Co. of Arnold, Mo., had been hired to do structural repairs to the two-lane, historic bridge at Washington, Mo.
The 73-year-old bridge is one of the last truss bridges across the Missouri River. Most have been torn down and replaced with newer designs.
After installation of a “Safe Span” system under the bridge to give crews access to the work area, inspectors got a more up-close-and-personal look at the bridge’s underpinnings than earlier inspections allowed.
Safe Span creates an entire deck underneath the bridge to allow for “very meticulous inspection of the structure,” Dolan, St. Louis Bridge Co.’s executive vice president, said.
What inspectors found was surprising — the deterioration was more extensive than thought and repairs needed were greater than the original plan called for.
For Dolan, the news meant major changes. To begin with, Thomas Industrial Coatings Inc., of Pevely, Mo., the painting contractor, was to begin work in early May, soon after the Safe Span went up.
“We were set up to close the bridge on the first of May after we had the access system installed,” Dolan said. “Our structural steel material was being fabricated to complete the main structural repairs for the entire job and in conjunction with the painting job, which was to go on concurrently.
“It was a very challenging process to change directions and get the structural repairs completed before the painting was done.”
The findings of additional deterioration and the engineers’ determination that the work had to be done before draping the bridge with tarps because it would create too great a load on the bridge meant “totally revamping” the schedule, Dolan said.
And then there was that little problem of the getting more materials.
“We had to go to our fabricator and get them to accelerate [their work] to produce the material three to four times faster than the schedule had shown,” he said. “We then had to bulk up our iron work crews to get those repairs made.”
With the additional repairs, the painter did not get started until the sixth of July, “a full two months after we had anticipated starting,” Dolan said. “In order to get done by December, which was our original completion date, we had to accelerate and make up two months’ worth of work.
“That kind of upsets the applecart when you have to totally throw away your schedule and start from scratch to get it completed.”
But by working with Missouri Dept. of Transportation (MoDOT) personnel on site as well as with the bridge division, Dolan’s company was able to right the applecart and complete the project on time.
The altered schedule, however, created another challenge — getting all the painting work done before the weather turned, Dolan said.
But the subcontractor managed to do it.
“The only remaining thing we had left to do, which we completed in January and February, was removing the access system,” he said.
Special equipment used on the job included the small Broderson Carry Deck cranes that “can operate up inside the truss area with a great deal of ease,” Dolan said. “The painting contractor had some interesting equipment — their recovery system and big blowers and compressors and stuff like that”
Crews used HEPA vac systems to recover and recycle the lead, he said.
“The amount of equipment was not huge but there were some different types of equipment that you don’t get on a lot of jobs.”
Staging for the project was done from either end of the bridge and the closed lane on top of the bridge rather from barges in the river, Dolan said.
“The specs said they could not stage from the river,” he said. “I guess they didn’t want to impede river traffic.”
Weather, always a major factor in road work, impacted the project, Dolan said.
October saw a record amount of rainfall — the most since experts began tracking such things.
“That really hindered progress in October,” Dolan said. “It was tight. We were working two shifts and a lot of times seven days a week. You plan the work but you don’t always get to work every hour of every day that you want to. When you get bad weather and you’re getting to the point that temperatures are critical, the work must get done. It intensified the schedule.
The painting contractor painted only what’s called “the splash zone,” not the entire truss, Dolan said.
“This was totally preventive and maintenance type of repair,” he said. “The splash zone was painted eight ft. above the bridge deck to protect it because that has the most deterioration and takes the most abuse of the salt and chloride coming off the road deck and hitting it.”
Crews repaired some 2,300 ft. (701 m) of the bridge in the $5 million project.
Dolan is quite familiar with the Route 47 bridge. He and his company did a major rehabilitation of the bridge in 1996. At that time the repairs were to the deck. This time it was to the lateral bracing under the bridge deck “repairs that nobody could really see,” he said.
Just as in 1996, traffic control was a challenge. Dolan was mindful of the need to keep one lane of the two-lane bridge open most of the time with minimal closure of the entire road. The main reason: a hospital sits at one end of the bridge as does an urgent care facility. It was critical for emergency vehicles to have access to it at all hours.
A temporary signal at each end of the bridge with control set up in the Washington 9-11 dispatch center helped manage the traffic flow.
“We offered a preemptive service so when an ambulance or other emergency vehicle had to pass, it was given the green light,” Judy Wagner, MoDOT district engineer, said.
“The other bad thing is the school district has several square miles on the north side of the river as well so we had to work with all the buses to get the across to pick up and drop off kids in the morning and the afternoon,”
The bridge also is the only Missouri River crossing between Route 19 at Hermann, 30 mi. west and the U.S. 40/61 bridge in Chesterfield, 24 mi. east. Without the bridge motorists would have to travel 80 mi. out of their way on state highways to cross the river, she said.
Dolan estimated the repairs will extend safe use of the bridge by another 10 years. In fact, MoDOT officials are already working on a replacement for the bridge although no funding is available at this time for construction.
Wagner said the environmental impact statement will be complete by September 2011.
“Hopefully we’ll have some funding to begin our design and then construction after that,” Wagner said. “Funding is the big hold up. Right now I would like to see it built in 2016 or 2017 but it’s really going to depend on the funding.”
The new bridge, which would be built near the existing bridge, also would be two lanes “with wider shoulders and an eight- ft. protected bike/pedestrian lane that we could potentially widen to additional lanes in the future if necessary,” Wagner said.
One reason a new bridge is needed is the lane width.
“It’s a challenge to meet the width for federal standards,” Dolan said.
The bridge carries about 10,000 vehicles a day. It is estimated that number will climb to about 15,000 vehicles a day in 20 years.
“We’re hoping to get seven to 10 years [of additional life out of the bridge] depending on the deterioration of the rust that’s already that’s down underneath there in those joints and gusset plates and so forth on the bridge,” she said. “It is going to depend on how severe our winters are and the growth rate of that rust and how much deterioration occurs over the years.”
Some residents are calling for keeping the old bridge because of its historic nature. But Dolan noted that even closing the bridge to vehicular traffic and using it for foot and bike traffic would be costly to the state.
“Taking vehicular traffic off of it will extend its lifespan greatly but it still would require maintenance and inspection,” he said. “It would take some money. As short as dollars are, it would be difficult to justify a major structure like that to continue maintenance on it for pedestrians and bicycles.”
Dolan commended MoDOT for being proactive and doing repairs that “were necessary to prevent a catastrophe like Minnesota,” referring to the 2007 collapse of the I-35W Mississippi River bridge that killed 13 people.