Southwest NH Transportation Infrastructure Vulnerability Assessment 

Some of the most pressing threats to infrastructure in Southwest New Hampshire are extreme storms and flooding. Extreme rainfall events in 2005 (Alstead) and 2006 (Keene and surrounding communities) brought severe flooding resulting in costly road washouts, property damage, and loss of life. The trend of increased frequency and intensity of weather events is well-documented as indicated by a number of federal disaster declarations impacting the Region over recent decades and recently (e.g., July 9-17, 2023 and July 29-August 2, 2021). Much of the Region’s stormwater and roadway infrastructure (e.g. culverts and bridges), is aging and in need of repair, and does not have the capacity to handle the extreme storms and flooding experienced in recent years. Ongoing and future changes to climate are expected to compound these risks resulting in significant impacts on infrastructure and associated maintenance costs. For example, New Hampshire Climate Assessment 2021 found that annual precipitation in New Hampshire increased 8.1 inches or 19% since 1901 and 3.7 inches or 8.7% since 1971.

Henry Underwood and Jason Cooper of SWRPC staff kicked-off work on the region’s first ever transportation infrastructure vulnerability assessment. The assessment will focus on precipitation-related impacts to publicly-owned roads, bridges and culverts. The project will use the Federal Highway Administration’s Vulnerability Assessment Scoring Tool to organize and weight many factors including asset condition, age, flood history and probability of being overtopped. SWRPC also plans to summarize information about climate and weather hazards relevant to transportation infrastructure and identify both short-term and long-term strategies (including projects) to address vulnerable infrastructure. For more information, please contact SWRPC staff: Henry Underwood at [email protected] or Jason Cooper at [email protected].