Mile Long Bridge Behind the Scenes: Massive Beams, Oversized Loads, and Exceptional Coordination

Mile Long Bridge Beam
If you’ve tuned in to Chicago traffic reporters lately, you’ve certainly heard about the massive concrete beams being transported to the Illinois Tollway’s Mile Long Bridge project, an important component of the Central Tri-State Tollway (I-294) Project.

It may look like just a massive piece of concrete making its way down the road, but the truth is there is a precise, coordinated effort to orchestrate the production, transport and placement of those beams.  

 

The OMEGA team as the Owner’s Representative and Construction Corridor Manager of the Central Tri-State Tollway (I-294) Project, plays a central role in ensuring this project keeps moving.  

Mile Long Bridge Project: The Background 

As part of the Illinois Tollway’s 15-year, $14 billion Move Illinois Program, the Illinois Tollway is rebuilding and improving the Central Tri-State Tollway (I-294) to modernize and improve the existing roadway to provide congestion relief, meet future transportation demand and address regional mobility needs. 

The Tollway has committed $4 billion to reconstruct the Central Tri-State Tollway (I-294) from Balmoral Avenue to 95th Street including the Mile Long Bridge. 

The Mile Long Bridge, located at the southern section of the Central Tri-State Tollway (I-294) Project was originally constructed in 1958 and currently up to 150,000 vehicles travel on the Mile Long Bridge each day. The bridge is actually two separate structures – one to carry northbound traffic and the other to carry southbound traffic.  

The bridge has been maintained over the past 50+ years with repairs and patching, but the bridge structures have reached the end of their service life. Rebuilding the bridges will reduce disruption caused by further on-going repairs. 

How do You Build a Mile Long Bridge? Really Long Beams 

Due to new technologies and exciting innovations in the transportation, construction, and engineering industry, the Tollway is able to build the Mile Long Bridge with fewer piers utilizing longer beams.  

And when we say longer, we mean longer. 

The new concrete and steel beams for the Mile Long Bridge are massive—some measuring nearly 200 feet long, 90 inches tall and weighing more than 125 tons. That’s longer than the Chicago Water Tower and heavier than a blue whale 

But bridge beam production, delivery and placement doesn’t happen overnight. In order to get these massive beams to the worksite, there’s a lot of coordination that must take place, from the fabrication of the beams all the way up to beam installation day.  

 

 

How are the Beam Fabricators Chosen? 

Before any work can start, the beam fabricator is chosen by the contractor from a list of fabricators pre-approved by Illinois Department of Transportation (IDOT). The contractor puts out a request for bid for a beam fabricator while preparing to put in a bid for the Tollway project. The contractor requests prices and the lowest bid is usually chosen.  

For the Mile Long Bridge project, County Materials was selected by the general contractor, F.H. Paschen, to produce and deliver the concrete beams. Over the summer of 2019, County Materials began production of the Mile Long Bridge beams, the largest prestressed concrete bridge beams the company had made to date. 

Beam Production—It Takes Time 

County Materials will be producing 273 beams for the northbound structure of the Mile Long Bridge project. The wide flange beams to be used were chosen specifically for the project in order to span longer distances and reduce the number of piers needed. Fewer piers will ease the impact the new structures will have on the environment and businesses below. 

The beams are made from prestressed reinforced concrete.  Rebars and tensioning strands are assembled and aligned inside steel forms.  Once positioned, the prestressing strands are put in tension.  Then concrete may be poured into the form.  After the concrete has cured and achieved the required strength, the tension on the prestressing strands is released.  The tension that these strands exert on the surrounding concrete greatly increases the overall strength of the beam.  The overall process takes approximately 60 days until the beam is ready for installation. 

Mile Long Bridge Sunset

What Work Needs to Be Completed Prior to Beam Delivery? Preparing for Delivery

Before the beams can be delivered on-site, there are several components of the Mile Long Bridge project which have to be completed prior to beam delivery. All the substructure (pier) work including drilled shafts, columns, and pier caps are constructed for each unit before beams can be delivered. Grading and compaction of the area near the piers and along the access road must take place so that the soil pressure under the equipment has the minimum capacity to support the weight of the cranes and trucks carrying the bridge beams. 

Prior to starting the work on the ground that must be done, the contractor is also required to submit a beam placement plan which is reviewed by the engineering team, including the Construction Corridor Manager, OMEGA. The placement plan is prepared by a structural engineer and includes calculations and drawings required to ensure the proper equipment is used and safe procedures are followed. 

Mile Long Bridge Beam Delivery

Beam Delivery Permits 

A few weeks before beam delivery is scheduled to begin, the beam fabricator works with IDOT, local police agencies, and the Illinois Tollway to acquire a superload permit for each of the vehicles carrying a beam.  

Superload permits are required for vehicles if: 

  • The width is greater than 12 feet. 
  • Any axle exceeds 25,000 pounds. 
  • The gross weight is greater than 120,000 pounds. 
  • Any tractor tandem is greater than 48,000 pounds. 
  • Any trailer tandem is greater than 60,000 pounds.  
  • Any trailer has two or more tandems.  

The permit is approved by both IDOT permit engineers and Tollway permit engineers, and the review must also include bridge engineers to ensure bridges on the delivery path can withhold the weight of the beams and have adequate vertical clearance. The permit application also includes the approved route and travel speeds for the beam delivery which the manufacturer must strictly adhere to. 

Mile Long Bridge

Beam Delivery Coordination with State Police 

The manufacturer also works directly with the Illinois State Police and Wisconsin State Police to coordinate beam escorts, as well as perform tractor-trailer inspections at the Wisconsin/Illinois State line. The beams come from Janesville, Wisconsin and Wisconsin State Police escort the truck from the manufacturer to the Illinois state line. Here the Illinois State troopers inspect the beam to ensure it is secured properly, according to the Federal Motor Carrier Safety Administration regulations and escort the beam through Illinois to the worksite. In addition to the trooper escort, each beam has three private escort vehicles furnished by the manufacturer. 

Mile Long Bridge Beam

Beam Delivery Schedule 

Once the permit is received by the manufacturer, the Construction Corridor Manager OMEGA hosts a meeting with all key stakeholders to review the entire delivery plan before beam delivery begins. The Illinois State Police permit requires that moves cannot be made when the highway is covered with snow or ice, or when visibility is unduly impaired by rain, snow, fog, smog, or at any time travel conditions are deemed unsafe by the Illinois State Police. 

Once all this has been completed and conditions are clear, the beam is able to head down to the worksite in Willow Springs with its escorts. The manufacturer can deliver anywhere from three to six beams each day, and with more than 270 beams to erect for phase one of the Mile Long Bridge, beam delivery will continue over many months. For the northbound Mile Long Bridge, beams are delivered either from LASMA island, a Metropolitan Water Reclamation District (MWRD) of Greater Chicago plot of land between the Des Plaines River and the Chicago Sanitary & Ship Canal or from the existing northbound I-294 bridge deck.  

Mile Long Bridge Beam Delivery

What Happens When the Beam is on Site? 

At the time of delivery, there are several different team members on-site including ironworkers, laborers, surveyors, operators and a few carpenters. The ironworkers initially install bracing, which is cross-sectional steel used to stabilize the beams on the pier caps. After the second beam in a span is placed, the ironworkers connect the beams to each other using cross members to finish stabilizing the beams.  

Mile Long Bridge Beam Erection

Special Considerations on the Mile Long Bridge Project  

With every construction project, there are always special considerations and unique challenges. The Mile Long Bridge presents interesting challenges such as placement over three waterways, grading along the banks of the river, and delivering beams from an existing bridge deck while also maintaining live traffic.  

Some may wonder, why can’t the beams get delivered all at once instead of one by one? Beams must be delivered one at a time for many reasons, such as to avoid double handling of the beam and to minimally impact traffic. 

OMEGA’s Role on the Mile Long Bridge Project 

If you’ve made it this far, you might be wondering—what is OMEGA’s role on the Illinois Tollway’s Mile Long Bridge project? OMEGA serves as the Owner’s Representative and Construction Corridor Manager of the Central Tri-State Tollway (I-294) Project. As Owner’s Representative, we’re responsible for all aspects of the project, linking every element of planning, design, and construction.

As Construction Corridor Manager, we focus on managing all aspects of construction, working directly with the Construction Managers and contractors to ensure the Tollway’s project is executed on-time and within budget. 

Mile Long Bridge Beam

About the Author

Steve Musser is the Traffic Operations Manager for OMEGA’s Construction Corridor Management team. With more than 40 years of experience working with the Illinois Tollway in the Engineering Department, Division of Maintenance and Traffic in various roles, Musser is very familiar with Illinois Tollway Policies and Procedures. 

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