What stop lights ??
Filament or LED ??
Traffic stop lights normally run on mains voltage.
In New Zealand 230 Volts ac, in the USA 117 Volts ac, although low voltage variants may be around which run at 48 Volts ac or dc or pehaps less.
First use an adjustable ac / dc powersupply and check from 12 volts up to 32 volts.
Then try
running the lights in series with a 117 Volts, 25 Watt bulb so at least you limit the current and don't have full fireworks if not already.
it is interesting that no voltage data is on your lamps questioned.