Chapter 3 recap
Rail and handover
The key takeaways from this chapter’s 2 lessons.
Rail for BIM people
- Track geometry adds cant (one rail higher than the other on curves) and transitions to the usual alignment.
- Clearances are checked against the space the moving train needs (gauge and kinematic envelope), not just the track.
- Work near the line happens in short possessions; sequence and logistics drive the design.
- Rail assets are located by line reference and mileage or chainage; IFC 4.3 adds rail elements and cant.
Handing over to GIS
- The owner's GIS has its own data model: feature types, attributes, code lists and identifiers.
- Networks need connectivity (what connects to what), not just shapes, so operators can trace and isolate.
- As-built positions carry their survey method and accuracy, like any utility record.
- Agree format, CRS, identifiers and acceptance checks at the start, and test a sample early.