TZ Bridge Bike Path Files from the NYS Thruway Authority

Construction started on the Gov. Mario M. Cuomo Bridge, better known as the Tappan Zee Bridge (TZB), in 2013 and opened to the public on 8/26/2017. The bridge includes a Shared Use Path (SUP) for bicyclists and pedestrians, which opened on 6/15/2020.

The surfacing of the SUP consists of approx. 1.5 inches of “thermoplastic polymer modified, dense graded, asphalt pavement”, topped with a blue methylmethacrylate paint. The asphalt pavement was applied over a tack coat, and the tack coat was applied to a membrane on the bridge’s deck panels.

Diagram of pavement construction, “Pavement Condition Report”, 2/2021, page 3.

“Slightly elevated, circular raised mounds or blisters” were observed in the pavement of the SUP and also in the shoulders and roadways of the bridge. A survey of the blisters was conducted on 9/16/2019-9/17/2019, and another investigation took core samples of the blisters on 6/22/2020-6/26/2020 for testing. Blisters were found to occur more predominantly in pier-supported sections of the bridge, and less so in the suspended spans.

Core sample taken, “GMMC Bridge Pavement Condition Report Appendices”, page 91.

“Task Order Number 16” was issued by the Thruway’s engineer to a consultant to investigate the blisters on 4/16/2020 for a not-to-exceed amount of $65,361. Task Order Number 17, superseding Task Order Number 16, was executed on 8/28/2020 and increased the not-to-exceed amount to $105,605.

Blisters were also identified in the westbound shoulder of the roadway. “GMMC Bridge Pavement Condition Report Appendices”, page 98.

A February 2021 report theorizes the possible causes of the blisters to be contamination of the tack coat, missing tack coat stripped away by construction equipment tires, improper application of the tack coat, differences in the form of vibration used by compactors, or other causes.