Bridge project on schedule for Saturday; span will be floated downstream Saturday morning
By Tuesday, the landscape in Hastings will be significantly altered for the next 100 years.
The main span for the new Highway 61 bridge here is on schedule to be floated in place, jacked up and secured by the end of the day Monday, Sept. 24.
That means the current bridge will close to traffic starting early Saturday morning, Sept. 22, and continuing through Monday. The timing of the move and lift has been delayed several times, but it does appear as though things are on schedule for this weekend. The timing may end up working out well for most parties, including the Hastings school district, which doesn't have school on Monday because of a staff development day.
The 6.5 million pound, 545-foot long span is floating on two barges in the Mississippi River since crews rolled it off land here on Sept. 7. While they were confident it would be fine on the barges, having that massive structure out in the water has certainly given them all at least a little cause for concern.
The project manager from the Minnesota Department of Transportation, Steve Kordosky, put it this way Wednesday morning: "It will be a good thing to get this finished and complete."
Here is the schedule of the move this weekend:
At about 6 a.m. Saturday, the current bridge will close to traffic. Shortly thereafter, two barges will push the span down to the project site, a distance of about a half-mile. The bridge should be in position by 9 a.m.
The next step will be to roll the span off the barges and onto a rail system. This should begin around 10 a.m. Saturday. This process will take until Sunday afternoon to complete. Wind at this point can be no more than 20 miles per hour.
The rail system will help the span get into the precise spot where it is directly below the four strand jacks that will lift it in place.
By Sunday night, the lift will begin to take place. The span needs to be lifted about 50 feet from the rail system to the top of the piers.
The lift will take place overnight and should be complete sometime early Monday morning.
Crews will then secure the span in place, which would take the rest of Monday. It could be quicker, but MnDOT is planning for a 72-hour closure of the bridge.
Here is more information on the lift:
Four jacks are used in the lift. Each one is mounted on a lifting frame that is resting on top of the piers. The hydraulic jacks are three feet wide, three feet deep and nine feet tall. They each weight 9,200 pounds.
They each have a capacity of just less than two million pounds.
Each jack will have 54 strands that run through it. That means a total of 216 strands that will be used to lift the bridge those 50 feet.
The strands are attached to the bridge with a series of bars and a pin connection.
Each strand is 18 millimeters in diameter. They are made of high strength steel.
Cranes have been used to set up the lifting frames and the jacks, but they won't be used in the move itself.
There are no guides used in the lift. The jacks are positioned on top of the piers so that the span will be lifted straight up.
The lift has a lower wind threshold. Steady winds can't exceed 15 miles per hour.
There are two separate crews working during the process. The crew that moves the span on to the rail system and into place consists of about eight employees of Mammoet, the Netherlands firm that is the sub-contractor for the move.
Another eight-person crew takes over for the lift.
In addition, the contractor for the project, Lunda/Ames, will have a crew of about 10 people assigned to the move and lift.
The self-propelled modular transporters that were used to move the span from land to water were quickly whisked away to Hastings and sent to different locations to be put back to work. They are now at projects in Canada and Wisconsin, among other places.