An integrated map of all utility services in a locale would facilitate better management of the road infrastructure and the utilities themselves. To meet this goal, there exists a need to integrate raster scans of paper maps into GIS by capturing the semantic relationships between the ob- jects in the drawings. In this context, commercially avail- able vectorisation algorithms do not produce a su fficiently rich object representation. We present a structural object recognition system that successfully isolates sectional sub- diagrams in maps of underground utilities. This is built upon a vectorisation system based on a constrained Delau- nay triangulation of pen strokes.