Updating Culvert and Storm Drain Design and Installation Methods

Analyzing Hydroplaning Potential on Wide Roadways

  • Catherine Earp
  • Rick Renna (FLDOT)


A cost effective design preference for widening roadway sections is to expand lanes to the outside with a continuous cross slope, rather than expand and slope lanes to the inside. This preference increases the water film thickness along the cross slope and raises concern regarding hydroplaning potential. FDOT and University of South Florida developed the software, HP, a hydroplaning assessment tool, to better predict hydroplaning potential using roadway parameters such as pavement type, pavement temperature, lane width, lane slope and longitudinal slope. The program has two components (1) a methodology to predict water film thickness (WFT) on the pavement being analyzed; and (2) a methodology to predict potential hydroplaning speed given the WFT determined. Hydroplaning potential is compared to the predicted driver’s speed, which is a factor of the design speed combined with the predicted driver’s speed reduction due to the visual impairment caused by a rainfall event. Predicted driver speed reductions were obtained using a driving simulator to measure driver’s response during simulated rain events. The results were calibrated to real-life driving data collected on Florida’s interstate system around the state. Analyzing the hydroplaning potential allows designers to better quantify the risk associated with wide section roadways having a continuous cross slope and decide when it would is beneficial to break the slope to decrease risk. Identification of recently approved, wider Florida typical sections with design speed restrictions will be discussed and complemented by an HP demonstration and sample problem discussion.

How to Cite:

Earp, C. & Renna, R., (2014) “Analyzing Hydroplaning Potential on Wide Roadways”, National Hydraulic Engineering Conference 2014 1(2014).

Rights: Copyright © 2014, Catherine Earp and Rick Renna

Publisher Notes

  • Panel moderated by Andrea Hendrickson, MNDOT.
  • About the Presenters: Rick Renna was born and raised in Key West, FL, moving later to the Ft. Lauderdale area where he joined the Florida DOT in 1974. He currently lives in Tallahassee with Gail, his wife of over 33 years, and has two children – Susanna (26) and David (24). In his spare time, Rick enjoys outdoor recreation and playing music. Career History Outline • Began with the Florida Department of Transportation (FDOT) in 1974 • Served in Construction from 1974 - 1986 as an estimates engineer, segmental bridge inspector, and a construction project engineer • Graduated from Florida International University and became a registered professional engineer in 1987 • Worked in hydraulics design from 1986 through the present • Managed bridge scour research since 1988, including the development of FDOT’s bridge scour equations • District 4 Drainage Engineer from September 1995 – late 1998 • Assumed the duties of the State Drainage Engineer in September 2001 • Responsible for FDOT coastal engineering policies • FDOT representative on the Board of Directors of the Stormwater Management Academy at the University of Central Florida. • Member of AASHTO Technical Committee on Hydrology and Hydraulics in 2001, Vice-chairman 2007, and Chairman in 2009 -2011 • Responsible for statewide stormwater management policy in FDOT Career History Narrative Rick Renna began his tenure with FDOT in 1974, serving in construction until 1986, when he transferred to Drainage Design. He graduated from Florida International University and was registered as a professional engineer in 1987. Rick began managing bridge scour research in 1988, overseeing the development of FDOT‘s scour equations. Rick served as the District 4 Drainage Engineer from 1995 - 1998 and became FDOT’s State Drainage Engineer in 2001, assuming responsibility for FDOT’ policies in hydrology, roadway hydraulics, bridge hydraulics, coastal engineering, pipe materials selection, stormwater management, and erosion and sediment control.

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Published on
21 Aug 2014
Peer Reviewed