Gate ACDs at manned and unmanned level crossings also warn passengers with the message 'Train Approach'.
A new ACD Version-II, now called the Train Collision Avoidance System (TCAS), is under development by The Research Designs and Standards Organisation (RDSO).
This has inherent problems as with GPS service and course acquisition, the best possible horizontal accuracy is 10 m. This is inadequate for detection of rail tracks separated by a distance of 10–15 feet (3.0–4.6 m).
The ACD system used in Indian Railways has inherent problems in station sections due to their design, using GPS for unfeasible track detection.
The High-Level Safety Review Committee at Mumbai on 12–13 January 2012 at the Western Railway HQ was skeptical of ACD effectiveness.
They unanimously chose to develop TCAS as an open architecture system without charging royalties unlike the ACD which is proprietary.