TBTC Testing Jan 30, 2011 20:53:33 GMT
Post by norbitonflyer on Jan 30, 2011 20:53:33 GMT
Indeed the RAIB categorises SPADs as being of four types - three of which are "unavoidable" (caused by a signal going to red in front of a train for example due to emergency or technical fault,) and with no less than 28 degrees of seriousness based on the potential or actual consequences, including how far into or beyond the overlap the train went.
The general public rarely understand that "running a red" on a railway is a very different matter to doing so on the roads. In normal use a railway signal should never go to red ahead of a driver, as it does on the roads - leading to "amber-gambling", which can save a driver a several minutes at some junctions. In contrast, there is nothing to be gained by passing a red signal on the rails: if the signal is red the line is simply not ready for the train for some reason: at best, you will end up going the wrong way.
The difference is best realised bt thinking about the difference between amber/yellow signals in the two environments. On the roads, an amber signal is a warning to approaching drivers that it is about to go red. On the rails, if it changes in front of an approaching driver at all, it will be to green.