Steel Panel Bridge Improves Load Rating of an Exiting bridge for Transmission Line Access in a Rural Community on the Ohio and Kentucky Boarder
Rated to only 15 tons, a backroads bridge would not accommodate the contractors’ heavy line trucks. A Mustang Extreme 3-panel steel bridge provided the perfect option for improving the low-load rating of the existing, narrow bridge which had guardrails installed. Rated to 50 tons, the modular bridge was installed in sections between the guardrails and over the existing bridge.
To work within the confines of the existing bridge, the installation was completed in reverse order:
First, outside panels were connected to center support panel.
Second, chain rigging was run through the 3 bridge panels and tightened with tensioner ratchets. This facilitated the bridge staying as one piece when the end was lifted to install the abutments.
Third, the bridge end was lifted and 4’ wide 12” thick abutment crane mats were placed underneath. This accomplished setting the bridge and building up from both ends, as the existing roadway bridge allowed us to drive and place the steel-panel bridge over top the lower-rated bridge.
The bridge needed a minimum 5’ abutment support. Using 2 crane mats per side, 1.5 mats were positioned under each end of the bridge, leaving two feet crane mat sticking out on each end to create a sturdy base for each ramp.
The combination of crane mats and aggregate achieved the abutments required plus the construction on/off ramps.
One requirement of the project was to accommodate local homeowners needing to drive over bridge with low riding cars. The installation crew expertly built and graded with aggregate onsite using rip rap and then progressively smaller stone built up as ramps and “feathered in” for a gradual on/off slope.
Not pictured: Mustang’s customer will return to site and add SWPPP controls around the bridge and ramps and periodically inspect around rain events/prolonged usage
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