I've just noticed a sign has appeared at Cambridge that says "do not open doors this side". It's in the ballast on the "off" side of platform 7, near to the footbridge, and appears to be new (as of the last week or so). I can understand why you wouldn't want to open the doors on the wrong side, but why does it need a sign all of a sudden?
To remind the driver to open the doors on the correct side. There may have been recent incidents at the station of a wrongside release and the sign is designed to mitigate that risk.
Muscle memory or 'autopilot' plays its part in wrongside door releases, especially in stop/start metro type work. If you've made 20 left hand door releases one morning, when you come the 21st which may be an offside platform you need a strategy in place to prevent your fingers reaching for the left hand buttons. At some stations there is signage. Some drivers will cover the buttons, others will use risk triggered commentary, a considered pause once stopped etc. Each company's driving policy may recommend different approaches, especially after an incident.
More modern rolling stock has (together with trackside equipment) the ability to prevent a wrongside door release, or at least ask you if you are sure in your selection.
