FSA was contracted by Amtrac, a railroad construction company, to provide surveys and associated engineering services for their work at the Martin's Yard railroad car repair facility located in Baltimore, MD and owned by the Maryland Transit Authority. The facility is used as a maintenance area for MTA. The original use of the facility was a World War ll bomber painting operation. In order to provide proper ventilation for the workers a massive series of underground concrete tunnels were constructed. The warehouse and surrounding area was retrofitted as a rail maintenance operation. It was discovered that the rail cars and locomotives entering the building were rolling over these tunnels. In some cases the depth of concrete was inadequate to support the loads. FSA was hired to complete an as-built survey of all above ground features, rails and structures. In addition FSA was also hired to locate and survey all the underground tunnels.