WHAT LIES BELOW, PART 2: CITY INFRASTRUCTURE by Jan Cermak PhD PE, Principal, Mueser Rutledge Consulting Engineers
Fig. 1 - NYC Subway and Utility Construction near Elm Street, ca. 1900 (Source: NYCPL)
Most owners and developers that have developed sites in New York City realize the importance of understanding potential impacts of adjacent buildings, other structures and city infrastructure on their developments plans. These impacts may have significant influence on what can be reasonably designed and constructed on any site. The New York City Building Code includes a chapter (Chapter 13) that is fully dedicated to Safeguards During Construction and Demolition. This chapter discussed requirements for protection of adjacent buildings and infrastructure. Additionally, the NYC Department of Buildings follows more specific requirements for protection of historic and landmark structures.
Fig. 2 - 1904 IRT Subway Plan (Source: nycsubway.org)
Developers and owners are typically familiar with challenges of construction in dense urban setting next to existing buildings, retaining walls or building backyards. Negotiating access agreements with adjacent property owners is something that is often undertaken in the very early stages of design process. While these are typically prepared and negotiated by specialty real estate attorneys, engineers should review the technical language of such agreements (e.g., criteria for vibrations and building movements). The technical conditions of access agreements can significantly impact the design and construction. New
York
City
has
extensive
infrastructure
which
includes both above grade and below grade works (Fig. 1). New construction may have potential impact on such infrastructure. When considering interaction with any development, the NYC Building Code requires that whenever construction is within 200 feet of NYC subway or other railroad tunnels/structures, an approval and permit needs to be obtained from the authority having jurisdiction over the tunnel/structure. The presence of transportation infrastructure is generally easy to identify. However, establishing limits and depths of below grade tunnels and other transportation structures can be a challenging and often requires some research (Fig.2 is an example of historic subway map showing subway location and profile).
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