Planning , prioritizing , and protecting bridge assets
Hillsborough County established a bridge asset management program and hired consultants to provide services ranging from emergency inspections to hydraulic reviews to structural design . The program started in 2017 with two consultants and was expanded by four consultants in 2019 . Ayres has been one of those consultants since 2017 .
QUICK RESPONSE :
Bloomingdale Avenue over Buckhorn Creek
When a bicyclist fell through a hole in the sidewalk near the Bloomingdale
Avenue bridge over Buckhorn Creek in Brandon , it was obvious there was a problem . The County closed a lane of the roadway and called Ayres to come to the site immediately , sharing a few photos along with the request .
Abdul Al-Rawashdeh , the County ’ s assets management engineer for pavement and bridges , said the program provides a bigger picture of the condition of the County ’ s bridges and estimates of the cost to keep them in good repair .
“ Missing from the inspection reports were budget factors ,” he said . “ The reports give the condition and a general idea of the bridge but no costs associated with it . That ’ s why we took another step to have consultants give in-depth evaluation and cost estimates .
“ Ayres does a very good job in creating those reports , giving the condition of the bridge , pointing out major and minor issues , how soon repairs will be needed and how much it ’ s going to cost , and at the same time discussing briefly how long we can extend the life of this asset – the bridge itself . This is the heart of asset management . We want to see how we ’ re going to spend the yearly budget to do major and minor repairs on the bridges .”
Hillsborough County has a $ 6 million budget this fiscal year for bridge asset management . If a bridge needs to be replaced , that funding comes from a separate budget . “ We want to use the money we have to maintain as many bridges as we can to make it safe for the public and at the same time extend the life of our structures ,” Al-Rawashdeh said .
At the scene , the team found a chunk of sidewalk had fallen straight down into a hole about 6 or 7 feet deep . When they looked inside , they found a 20-by-20-foot hole under the approach slab leading up to the bridge .
“ The County ’ s biggest concern is public safety , first and foremost ,” said structural engineer David Johnson . “ They needed to know how many lanes needed to be closed and if the structure itself was compromised or not .” Bloomingdale Avenue is a main thoroughfare in Brandon , so closing lanes meant disrupting traffic , at least temporarily . Fortunately , there was a fast fix for the immediate problem : flowable fill . This is a pumpable concrete mix that can be placed directly into a cavity to be filled . It ’ s good for filling irregular voids and hard-to-reach places , and it hardens in a few hours without the need for compaction . The County called out the Ayres team at 11 a . m . and by that afternoon concrete trucks were on the way to fill the hole . Johnson noted that so much concrete was needed to fill the hole that the filling process lasted into the second day . The quick action by County , consultant , and contractor allowed the repairs to be completed within 24 hours of the Ayres team being called to the site .
But that was just the immediate fix . It was clear that scour along the wing wall had created the hole – but how ? Johnson noted in the field that water was flowing directly at the wing wall ; that ’ s not how bridges are designed . Back in the office he reviewed the bridge plans and found that the ground line was originally much higher : “ Not a foot or two – 7 feet .” The channel had migrated over the years and eroded the streambank , with the flow now aimed directly at the wing wall .
Sand cement bags ( Florida ’ s substitute for rock riprap ) are temporarily protecting the structure . The Ayres team , including hydraulic specialists from Ayres ’ Fort Collins , Colorado , office , will be designing permanent scour countermeasures .
– Wendy Kinderman www . AyresAssociates . com 9