Grand Central Terminal was designed and constructed between 1903 and 1912, when district heating and steam distribution was in full development in NY. An extensive network of steam tunnels is located beneath Grand Central, and some parts of the steam system have been in operation for over 90 years. Steam is provided by Con Edison and distributed to various internal and external clients in Midtown East.
Because of the age of the system, it has largely been undocumented. Metro North Railroad commissioned an assessment of the steam system in order to assess and identify all equipment and document equipment condition.
Mott MacDonald was retained to provide a comprehensive and detailed assessment of the existing steam system. This included site surveys to identify all equipment and a condition assessment of all live steam system pipework and elements (anchors, valves, etc).
No accurate as-built drawings existed and the team was also tasked with development of highly detailed 3D CAD models of the entire live steam distribution network below Grand Central. All steam system elements were incorporated into a single database, with linked photographs, new identification tagging and condition ratings. A 3D CAD model of the steam system was produced using advanced laser scanning techniques (accurate to 1/8 of an inch).
In order to assess the condition of the distribution network, we performed nondestructive testing using Computed Radiography at over 2,000 locations. This allowed pipe wall thickness to be determined without disturbing pipe insulation. Finite element analysis using computer modeling was also performed to determine areas where the steam pipes were being overstressed.
Based on our findings, short-term recommendations were made to address immediate system safety risks and code violations.
Long-term recommendations were made to optimize overall system operation by improving energy efficiency, improving maintenance access and introduce redundancy in the event of steam distribution failure.
Mott MacDonald's recommendations will help Metro North to develop a rehabilitation plan to ensure safe and efficient operation in the future.