The End of an Era

A new bridge spans the Missouri River as its predecessor is demolished
By Genevieve Smith

The I-64 Daniel Boone Bridge is the name of two bridges carrying Interstate 64, U.S. Route 40 and U.S. Route 61 across the Missouri River between St. Louis County and St. Charles County, Missouri. The newer bridge was just recently completed in its totality this past summer. What started in 2013 with construction on the new eastbound bridge, the Spirit of St. Louis Blvd bridge over I-64, and a new Chesterfield Airport Road Bridge and North Outer Road connection, became a single project finished in phases.

First, the new Airport Road bridge and interchange opened in November 2014. Traffic was then diverted onto the new eastbound bridge by late spring 2015 and rehab work started on the neighboring bridge that was built in the 1980s and was completed by the end of the year. The project culminated in the demolition of the original 1930s-era bridge in early Spring 2016 and with the opening of the bike and pedestrian path along the new bridge earlier this summer.

Working in the river on a daily basis presented challenges all its own for the project team, like water elevation fluctuations that would distrupt work schedules and even destroy completed work.
Working in the river on a daily basis presented challenges all its own for the project team, like water elevation fluctuations that would distrupt work schedules and even destroy completed work.

To take a step back, the project really began much earlier, before the millennium even, when that area of Missouri started to see a large increase in population. “It was first noticed in the 1990s, as development boomed in St. Charles County and traffic on U.S. 40 (now Interstate 64) increased, that there was an overwhelming need for a new bridge,” said Jim Gremaud, project director for the Boone Bridge. In fact, he credits the eastbound bridge for really giving them the nudge to look at other options: “The new eastbound bridge that was built and opened to traffic in the late 1980s really highlighted the deficiencies of the westbound 1930s bridge,” said Gremaud.

Major deficiencies like the need for additional roadway capacity and shoulders, as well as return on investment of maintenance-time and -dollars in the form of longevity mounted up. Even after a road diet and restriping for the original bridge to make as much room as possible, there was no denying how essential a new bridge actually was. Also, with the extra space a new bridge would provide, the ability to add a shared use path across the river became a big influence.

9So the reality of a new bridge was established, as early as the early 2000s. Then came the logistics. “Any time you are building a bridge across a major river there are special challenges,” said Gremaud. “Working with all of the regulatory agencies (Corp of Engineers, Coast Guard, Department of Natural Resources, Levee District, etc.) and meeting their needs and doing what they need done always presents challenges.”

An example of one such regulatory obstacle, an Environmental Impact Statement was required. The original EIS began in the late 1990s and was completed in 2004. “We worked with our MoDOT environmental people and other outside agencies to make sure we were doing work in the river and in the forest at the time and in the manner that had the least impact to species identified to be in the area,” said Gremaud. Re-evaluations of the original EIS were completed and approved by FHWA in 2011 and 2012 after more project details were modified.

The end of the 19302-era Daniel Boone Bridge, which was demolished in two parts this past March after the completion of its brand new replacement. The steel that fell into the river post-explosion was removed and scrapped.
The end of the 19302-era Daniel Boone Bridge, which was demolished in two parts this past March after the completion of its brand new replacement. The steel that fell into the river post-explosion was removed and scrapped.

Also, working in the river on a daily basis presented challenges of its own for the project team. “The water elevation rises and falls regularly and can be very disruptive to work schedules as well as damage or destroy work that is underway or has been completed,” said Gremaud. Designing temporary and permanent substructure units and features for a river bridge, that can stand up to the forces and challenges a major river offers daily, requires much forethought and design expertise.

Other factors to be considered, the costs and risks involved with designing and building river bridges far exceeds the risks involved on most other transportation projects and must be taken into account when designing and costing work. Keeping all lanes of I-64 open to traffic during the majority the construction of this project also presented challenges and required several phases of work to get roadway work completed.

For Gremaud, though, most of these challenges were just in a day’s work. He mentioned navigating Indian burial ground and lessening the impact on local endangered species as merely ‘typical challenges’ for this type of project. In addition, the 1930s bridge is considered to be historic and certain guidelines needed to be followed as to how it could be removed.

The costs and risks involved with designing and building river bridges require careful consideration and multi-tiered organization and execution.
The costs and risks involved with designing and building river bridges require careful consideration and multi-tiered organization and execution.

The 1930s-era Boone Bridge was a feat of engineering and, although the bridge was eligible for the NRHP list, it was demolished in March 2016. The idea of maintaining the bridge as a bike and pedestrian trail was assessed, as the bridge could be capable of connecting the Monarch Levee trail on the Chesterfield side of the river to the Katy Trail in St. Charles county. Before fully deciding to demolish the bridge, the department even offered the bridge to the public, to any group or individual who would take over responsibility for the bridge, in order not to lose a landmark. But the costs associated with maintaining the bridge in a safe and functional state were just too high.

So the decision to move forward with the demolition was made, but the plan to connect the two trails remained and was cleverly incorporated into the newly-built bridge. Crews constructed a new bridge, and renovated the neighboring1980’s bridge before removing traffic from the 1930s bridge and then demolishing it. “The driving surface of the bridge was removed using concrete breakers, cutting torches and large equipment,” said Gremaud. “Once the driving surface was gone, the skeleton of the superstructure steel that remains was be removed by explosives.”  The bridge was demolished in two separate explosions, the driving surface was considered clean fill and was discarded appropriately, and the steel that fell into the river post-explosion was removed and scrapped.

All in all, the Daniel Boone Bridge project serves as well organized, multi-faceted infrastructure project that recognized an issue with an existing structure early, produced a feasible well-researched plan, and executed development, all under budget in less than five years of actually disruptive construction. Of the original $125 million allocated to this project, MoDOT set aside $8 million for internal costs – things like purchasing right of way, utility relocation expenses and to pay for construction overruns and contingencies. “MoDOT expected to spend no more than $6 million of the $8 million set aside for internal costs,” said Gremaud. “A total of $117 million was made available to the winning proposer and in this case the winning proposer’s price was $110.99 million. This was more than $6 million under budget.” That’s $6 million worth of infrastructure spending that any DOT across the country would be proud of saving.

Genevieve Smith is the Editor for American Infrastructure magazine. She may be reached at gen@penpubinc.com.

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