I-278 and the Triple Cantilever: A Tunnel Solution for the BQE

Abstract

American highway engineers have long struggled to build efficient highways through urban areas. The strength of America's system of interstate highways comes from its long stretches connecting urban areas. Goods move quickly over these multi lane highways that reach nearly every corner of America. The flexibility of the less developed locations where these interstate links exist makes the engineering straightforward. However, in urban regions, highway design is decidedly more challenging. Indeed, the legacy of urban interstates is not a good one - urban highways are criticized for careless design which broke up neighborhoods and contributed to inner city decay. Opportunities do exist for correcting this legacy. Today, engineers focus on the effects of highway construction on urban green space and neighborhood preservation. This thesis will propose a project which contributes to the effort to correct the past ills of urban highway construction and serve as a case study for remedying the problem of poor urban transportation systems. By routing Interstate 278 through a bored tunnel in Brooklyn, NY, the project preserves the important transportation capacity which interstates provide while also removing the blight of above ground urban highways. This project will present a framework for other urban highway projects. The Tillary Street - Atlantic Avenue Tunnel will be a single bore tunnel carrying six lanes of traffic beneath the neighborhoods of Brooklyn Heights and Downtown Brooklyn. This Thesis will lay out a preliminary design for the tunnel and a financial analysis establishing the economic value of the project.