Gwynedd Cut Rail Line

A rail line owned by the Southeastern Pennsylvania Transportation Authority (SEPTA) and used for high-speed passenger trains travels through an area known as the Gwynedd Cut in Upper Gwynedd Township. SEPTA desired to have a reliable model for future maintenance, both proactive and for repairs, on this line.

Erdman Anthony provided 3D laser scanning (terrestrial-based LiDAR), with support field survey, to develop a digital-terrain model and a cross-sectioning plan of the rail line. The survey was referenced to North American Datum of 1983 (NAD 83), Pennsylvania State Plane Coordinate System horizontal datum, and North American Vertical Datum of 1988 (NAVD 88), in survey feet.

To allow for future conventional topographic surveying, a pair of intervisible control points was placed at the top of the cut.

As part of this project, Erdman Anthony personnel attended a SEPTA training course on field safety and conducted field operations in accordance with SEPTA guidelines.

The client received a MicroStation file containing 25-scale planimetric details, along with an InRoads DTM file. Cross sections at 25-foot intervals showed rail and rock-face features. The final deliverables also included a Leica Geosystems database (.imp) file, with all control data, multi-images, modeling information, and survey control points, on DVD.