FDOT State Route A1A along San Marco Avenue

Project Summary

Hanson worked with the Florida Department of Transportation to develop a unique, multi-intersection improvement concept to alleviate congestion and improve traffic operations at one of the gateways to the city of St. Augustine’s historic downtown. Hanson’s design involved separating two adjacent signalized intersections to form a single quadrant/offset T-intersection.

The project consisted of realigning the State Road A1A (May Street) intersection at San Marco Avenue, further offsetting it from the intersection at West San Carlos Avenue. The realignment resulted in dividing SR A1A into two legs. This and the addition of a northbound slip lane along San Marco allowed both signals to reduce to two-phase operations. The outcome was less time for a stopped condition and increased traffic movement. Elsewhere, dual left-turn lanes were added along West San Carlos Avenue, from SR A1A to the intersection of U.S. Route 1. A left-turn lane was extended along U.S. 1, and a sidewalk was added along the west side of U.S. 1. The design required minimizing impacts to a historic coquina knee wall along the right of way and coordinating with the Florida Division of Historical Resources.

In addition to roadway design and complex signing and marking, the highly visible project included design of a new closed drainage collection system to help alleviate a chronic flooding problem, stormwater treatment, new utilities and a utility conflict resolution, environmental permitting, cultural resources and significant public involvement. Hanson worked with the city of St. Augustine throughout the early planning process, which started with five alternatives. The roadway reconstruction required utility adjustments and relocations, as well as upgrades to signalization at the intersections of U.S. 1, San Marco Avenue and SR A1A.

Hanson also developed a new sanitary lift station, gravity sanitary sewer and force main to replace utilities affected by the improvements. Hanson replaced a cast-iron water main along San Marco Avenue and designed a new water main along the new SR A1A alignment.

Because of the relatively high pedestrian traffic within St. Augustine and the nearby Florida School for the Deaf and Blind, all intersections include audible wayfinding signals to safely assist on crossings. In addition, a High-Intensity Activated Crosswalk (HAWK) signal was provided to facilitate crossing SR A1A.