City of Boston: Climate Resilient Design Standards and Guidelines for Protection of Public Rights-of-way
In 2018, the City of Boston’s Public Works Department issued standards and guidelines for climate-resilient infrastructure to protect public rights-of-way from an expected 40-inch increase in sea level by 2070. In particular, the guidelines are intended to inform height adjustments for structures to account for sea-level rise, and establish a climate-resilient design process for shoreline barriers. City engineers and designers will be able to use these guidelines to inform designs for flood barriers protecting public rights-of-way to ensure they are prepared for the acute and chronic flooding conditions expected in coming years. Existing local and state regulations are not superseded by these guidelines.
The guidelines use sea-level rise (SLR) height adjustments of +9 inches for structures designed for use through 2030, +21 inches for 2050, and +40 inches for structures in place through 2070. The standards identify design adjustments that account for the sea-level rise/storm surge, and extreme heat and precipitation estimated by Climate Change Sea-Level Rise Projections for Boston. Barriers costing more than $10 million should undergo climate-based risk assessment related to their designs.
The guidelines set the freeboard standards for critical (2 feet above base flood elevation/BFE) and noncritical infrastructure (1 foot above BFE). For purposes of setting freeboard standards, critical infrastructure includes schools, hospitals, correctional facilities, food distribution centers, water storage and pumping stations, structures containing hazardous waste, transportation networks, and assets outlined in the city Risk Management Plan. In addition to SLR, designers and engineers should contemplate expected rises in precipitation and heat. The guidelines outline expected peak rainfalls and storm depths based on 30-, 50-, and 70-year flood events in order to inform designs. Also provided are ranges for expected heat increases through 2070. Lastly, the document provides guidance and information related to operations and maintenance cost considerations, a host of barrier selection and design factors, and the processes involved.
Four types of barrier are used as non-exhaustive examples for the design, cost, operations, and maintenance considerations contemplated by these guidelines. The concepts come from prior Climate Ready Boston studies, and include: vegetated berms, harborwalk (seawall) barriers, raised roadways, and deployable barriers.
Given that barriers’ useful lives may extend beyond 50 years, the Department suggests designers consider how protective measures can be adapted beyond a 50-year useful life, and public ROW barriers should be designed to last at least 50 years. Designers are encouraged to consider additional strategies and factors as well, including green and blue infrastructure, retreat, elevation, and the principles including social and environmental impact, value creation, and equity.
Publication Date: October 17, 2018
- City of Boston, Massachusetts
- Agency guidance/policy