2026 ACEC-NH & NHDOT Technical Exchange Conference

Session 4A: Coastal ResilienceHydraulic ModelingGuidance
Speaker: Cheryl Coviello, NHDOT; Michael Gardner, GZA
-The NHDOT Coastal Hydraulic and Hydrodynamic Supplement provides technical guidance for planning, engineering and design of NHDOT-managed transportation infrastructure for Tiers 1 through 3 roadways located within the Coastal Area. The Coastal Supplement includes a risk-based approach for developing design parameters, specific to the coastal environment, that considers uncertainties, non-stationary conditions, and the criticality and vulnerability of the transportation assets (roadway, bridge, or tidal crossing). Coordination for science and guidance with other NH agencies was valuable in its development. Once released for use, the Coastal Supplement will provide NHDOT staff and consultants with a framework for coastal project designs that prioritize both the “project” and the “system” performance.  

Session 4B: SR1 Coastal Corridor Resiliency Study for the Delaware Department of Transportation
Speaker: Jim Pappas, AECOM
-Due to the low-lying topography of Delaware, the state is susceptible to flooding not only during weather events, but due to tide cycles.  One of the most critical corridors exposed to flooding is 16 miles of State Route 1 (SR1) along the southern coast of the state.  This corridor connects the coastal communities of Dewey Beach, Bethany Beach, South Bethany Beach, Fenwick Island, all the way into Ocean City, Maryland.  SR1 is the primary evacuation route for all those communities so ensuring its resiliency is critical.  Additionally, the closure of SR1 between Indian River Bridge and Dewey Beach results in an 18-mile detour which is not only inconvenient, but critical for first responders.  
As SR1 provides the link for those looking to visit the Delaware beaches and provides year-round travelers and residents with ease of access to coastal communities, SR1 is vital to the economic well-being of the area and the state as a whole.
The goal of the study is to improve the overall resiliency of SR1 to reduce maintenance cost and ensure a direct route of travel for the coastal residents. This study also supports the 2016 Multi-Jurisdictional All Hazard Mitigation Plan and the 2018 State of Delaware All Hazards Mitigation Plan.
Within this corridor, the town of South Bethany has initiated work to review flooding within their community. They received grant funding and plan to raise York Road within their community to address the roadway flooding that occurs. The construction project has been awarded and construction is planned for spring 2026.