One thing that helps cooling, whilst sitting in traffic etc is to rev the engine.
Oh yes ❗ ❗
The water pump is a centrifugal type and at idle speeds does not spin fast enough to give a high pressure/ volume output. As the cooling is done by the rad, you need to deliver the hot water to it;
Revving up to only about 2000 or so will allow the pump to shift more water. The heat produced by the engine will not be significantly more than that at idle, but the water pump will be operating further up it's pressure/volume curve.
Just try it and watch the guage drop.
If that doesn't happen, you have a problem elsewhere;, Stuck stat, shagged pump, radiator full of air, etc.
IMHO
susser (1/2 🙆🏻d thermodynamicist )