Advertisement
  1. Transportation

Questions continue on bouncy Bayside Bridge

Published Aug. 18, 2012

Questions about the bouncing Bayside Bridge have been pouring into the Doc's inbox since we covered the issue in this column in May. Many readers insist that there are foundational issues with the construction of the bridge and have questioned the county's explanation that the rhythmic bouncing effect is due simply to cambers in the design of the bridge. Cambering allows individual concrete slabs to flex downward to a level position under heavy loads. The reasoning from the county was that bouncing is a common byproduct of bridge spans constructed with concrete slab spans.

This didn't hold water with readers, including several who identified themselves as engineers. The common theme of the emails and calls the Doc received is the perception that something went wrong with the construction of the bridge, which began in 1991 and was completed in 1993.

The Doc asked the county's engineering team to respond to four follow-up questions. We heard back from engineer Jorge M. Quintas, director of Pinellas County's division of engineering and technical support. Here is his response to our questions:

Was an error made in the construction process of the cement slab?

We are not aware of any errors in the construction process that can be directly attributed to the overcambering of some flat slab concrete segments at the south end. Cambering is a typical practice in bridge construction in which the superstructure is built with an upward deflection so that when the beam or slab is set in place it will deflect downward and assume a smooth riding surface in conjunction with the remaining spans. Overcambering took place on a portion of this bridge, and that is what drivers are feeling. Though this can result in an uncomfortable ride to a driver, it does not affect the structural integrity of the bridge.

Have corrective measures been taken to address the bounce? If so, what measures and when?

No corrective measures have been taken for the following reasons: This condition is extremely costly to correct, as the deck has to be milled, joints have to be replaced, and a deck overlay has to be poured. In most cases, a considerable improvement to the riding surface is not achieved after completing such costly corrective measures. Consequently, the cost-to-benefit ratio does not justify remediation. This condition is not wholly uncommon in bridges. As previously stated, the condition is primarily one of rider discomfort, and not one that generates structural concerns.

Was more than one contractor used in the construction of the bridge (hence the different feels)?

There are many subcontractors that work on large projects as these. However, they are all guided by the same contract plans and specifications. The contractor was Traylor Brothers Inc.

Why is the bridge so wavy/bouncy along one-quarter of the structure (south section of the northbound lanes) and not wavy/bouncy for the other three-fourths of the bridge?

We can only assume that, along the approximate bridge length of 2.65 miles, there was a nonuniform reaction to prestressed forces. A prestressed member will continue to deflect upward, or camber, for a considerable time after the prestressing strands are released at the casting yard. Not all prestressed members will react exactly the same, since their reaction can be affected by a multitude of factors. It would difficult, if at all possible, to ascertain what specific factor in 1991-1993 may have led to the uneven reaction of the prestressed members.

Email Dr. Delay at DocDelay@gmail.com to share your traffic concerns, comments and questions or follow Dr. Delay on Twitter @AskDrDelay.

ALSO IN THIS SECTION

  1. The Florida Department of Transportation is installing lights on the Sunshine Skyway Bridge as part of a $15 million project. During tests this weekend, engineers will illuminate the bridge in a pink hue to commemorate breast cancer awareness month. Courtesy of Florida Department of Transportation
    The Florida Department of Transportation is lighting up the span this weekend to commemorate breast cancer awareness month.
  2. The Pinellas Suncoast Transit Authority is hoping to secure a $21.8 million federal grant to help pay for a bus rapid transit line connecting downtown St. Petersburg and the beaches. St. Petersburg City  Council approved an interlocal agreement Thursday supporting the project. ALESSANDRA DA PRA | Times
    Pinellas transit officials hope the project will get a federal grant in 2020. However, St. Pete Beach and South Pasadena still oppose it.
  3. Yesterday• Business
    The Cross Bay Ferry, Provincetown III leaves the Vinoy Yacht Basin in January with passengers headed to Tampa. For departure times and fares for this season, which will go from Nov. 1 through April 30, check thecrossbayferry.com. [SCOTT KEELER | Times] SCOTT KEELER  |  Tampa Bay Times
    Now in its third year, the ferry will run Wednesdays through Sundays, with service for every Tampa Bay Lightning home game.
  4. Col. Jennifer Crossman smiles as Boomer, a 5-year-old dog, sits in the passenger seat of her car during the firefighter challenge at MacDill Air Force Base in Tampa. [Times (2016)] Tampa Bay Times
    Uber customers can now be connected with willing animal chauffeurs — for a fee.
  5. OCTAVIO JONES   |   Times Pasco County's long-range transportation plan no longer includes a proposed sales tax increase.
    The federally required plan guides transportation needs and expenses through 2045.
  6. Ryan Cummings, 23, of Tampa, left, and Alex Frey, 25, also of Tampa, rent Spin electric scooters from a corral located along Zack Street Tuesday, May 28, 2019 in Tampa. Electric scooter companies Spin, Bird, Lime and Jump were being deployed within the next few weeks according to a tweet from the City of Tampa on Sunday. Campbell and Henigan spent a couple of hours Tuesday trying the electric scooters. Frey and his friend Ryan Cummings rented two scooters during their lunch break. "We are going to Armature Works, we couldn’t do that without these." said Frey. CHRIS URSO  |  Tampa Bay Times
    Plus the most bizarre incidents of electric scooter vandalism around the city.
  7. The traffic signal for eastbound traffic on Drew Street at McMullen-Booth Road in Clearwater. Image by Archive
    A reader wonders why the sign at the end of Bayside Bridge instructs trucks heading north to exit during specified hours rather than stay on the bridge.
  8. In this Feb. 23, 2015 photo, a car is hauled from a canal in West Palm Beach, Fla. The driver was taken to a local hospital where he died. Palm Beach County has over 300 miles of canals, built to move water. Since 1997, 181 people have drowned in vehicles that ended in canals. (Lannis Waters/Palm Beach Post via AP) LANNIS WATERS  |  AP
    Of the nearly 1,100 people nationwide who died from 2013 to 2017 when vehicles went into water, 1 in 6 died in Florida.
  9. Dr. Daniel P. Greenwald, a well-known Tampa plastic surgeon, died on Oct. 5 when his twin-engine plane crashed soon after taking off from Kokomo Municipal Airport in Indiana. Greenwald family | Tim Bath/The Kokomo Tribune via AP
    An employee at the Kokomo Municipal Airport said Dr. Daniel P. Greenwald told him he wanted jet fuel for the Piper Aerostar. A friend says there’s no way he would have knowingly done so.
  10. Rekira Owens, a bus driver with the Hillsborough Area Regional Transit Authority, greets officials from behind a newly installed shield as they board a bus Thursday in Tampa. The clear divider is meant to protect drivers from physical assaults after a driver was killed in Tampa this year. CAITLIN JOHNSTON  |  Tampa Bay Times
    The two transit agencies took action after a Hillsborough driver was stabbed and killed by a rider earlier this year.
Advertisement
Advertisement
Advertisement