Definitely. This is probably the best argument against wig-wags put on this thread so far. The railway, whilst normally so insistent on fail safe systems has let itself down here. (Incidentally, Automatic Half Barrier Crossings also are not fail safe to the best of my knowledge - if the barrier sticks in the open position, then nothing will stop the train from hitting traffic.)
The wig wag road lights are the instruction to road users to stop. The barriers are additional protection.
As MarkyT says, there must be at least two wig wag signals visible to road users at either side of the crossing, each of which has two red lights. Also as he says, most are now LED type. But even when they were 36W or 50W filament lamps, the failure rate was sufficiently low that it’s very unlikely that a second lamp would blow before the first failed lamp was replaced by maintenance staff. All these lamps are current proved, as described above.
With all conventionally controlled level crossings, every effort has been made to make them as fail safe as possible. Hence at AHB crossings, the barriers are held in the raised position by hydraulic fluid which is itself controlled by an electrically controlled valve. Loss of electrical power to the valve releases the hydraulic fluid pressure and the barrier drops to the ground under gravity (the power feed is intentionally cut for normal lowering).
The maintenance frequency of level crossings is set to check that all barriers (as well as other equipment) are fully functional.
If a barrier drops for any reason, or a track circuit (or axle counter) fails safe at or on the approach to the crossing, then the red road lights come on. Plus, on automatic crossings, special rail mounted wheel detectors are used on approach to the crossing, as soon as a wheel passes over these, the crossing sequence is started regardless of anything else.
What would be ideal would perhaps be a signal that effectively says 'line is ready for the train in all ways except for the level crossing', which would mean that both the door closing and level crossing 'buttons' can be pushed so that everything is ready at the same time. A few seconds here and there do make a big difference - the railway is good at minimising delays impacting the trains, equal priority should be given to minimising delays (and so enhancing safety) to level crossing users.
This if done would have to have very careful thought about how it would work and what equipment would be provided. One of the fundamental rules is that any proceed indication to a train driver of a passenger train cannot be given unless it is safe for the train to proceed. The only exception is for a slow speed move on a permissive platform line where one train will join with another (such as DMU or EMU trains).
My point was that noone would accept a situation where a light out = go, red light = stop, no matter how many other safeguards are provided to be certain that the light hasn't gone out for another reason. Effectively an AHB crossing is similar to this situation - there is no absolute proof that the crossing is going to work before it is too late to stop the train.
The railway is stuck with what the legal requirements are. These are highways standards, not railway choices.
As said above, just with normal road traffic signals, failure of one light/lamp is covered by having multiple lights/lamps. Known as redundancy. Failure of a control circuit results in the red road lights coming on. Trust me, the circuitry and wiring is more complex than it needs to be in order to meet all the safety requirements.
If there are any allegations of a level crossing malfunctioning in an unsafe way, a very detailed and comprehensive investigation and testing process is started. All the crossing equipment and the control systems are fully examined and tested. And until the crossing has been proved to be working correctly, it will not be relied on to provide protection.
