Many cyclists jump red lights. Since they don't have number plates, they feel unlikely to be caught, so act like jaywalking pedestrians. Is there ever a good reason to jump red lights?
Our cities are full of traffic lights. There's often a set every 100m. Many cyclists feel that if they stopped at every single red light they'd never get anywhere. Of course the best plan of action is to cycle on quiet roads in the country, but not all of us can do this, especially when commuting to work.
There are a few problems with jumping red lights (RLJ - Red Light Jumping).
First of all is that it could be dangerous. Most people would consider themselves to be a good judge of their own safety, so feel equipped to decide when to RLJ. However it is often the case that a pedestrian steps out, or traffic comes quickly from an unknown source when accidents happen. It is a better policy to stop at red lights. A moment's inattention could cost you dear.
It is illegal (in most cases). Bicycles are classed as vehicles and so you should follow the road traffic laws in your country, which means stopping at red lights. If you are stopped by the police for RLJ you could well get a fine.
It enrages motorists. Whilst the majority of motorists are also pedestrians who don't think twice about crossing at a red don't walk, many of them get irate when they see a cyclist going through a red light. The anti-cycling lobby then question how cyclists can be respected when they always flout the law. It is my opinion that motorists get irate at the sight of RLJ because they would like to do the same but are stuck in their cars.
However there may be some situations where it is safer to go through a red.
The first is when there's a large truck trying to turn in front of you. Occasionally cyclists are crushed by turning trucks. If you are going straight on, then either stay behind the truck or move far out in front of it. You will need to be at least 10m in front of the truck to be seen. If you are also turning right (UK, AUS read left), then it may be a good idea to get out of the way by sneaking through a red. Your state may allow you to do this (Not New York or California).
The second time is when there's a lot of traffic backed up behind you and you are about to enter a fast, crowded and dangerous stretch of road. You don't want traffic trying to overtake you as soon as the lights go green. Better to get a head start and out of the way (perhaps if you are turning left not far along).
If you must go through red lights, then ensure that nobody can see you, ensure there are no police nearby, do not wear your club jersey, do not RLJ at large busy junctions and do not pass between pedestrians. It should be done discretely and safely.
Stop at red lights. If your trip will take longer as a result, then plan accordingly. Scattering pedestrians as you weave through them is not acceptable behavior for a cyclist.
In view of numerous injuries and deaths caused by turning heavy vehicles, it may be safer to proceed through a red light when turning right.
Do not make RLJ a habit. We are all ambassadors of cycling and should try to counterbalance the behavior of the 'guys on bikes' who do jump red lights.
Telegraph UK article about why cyclists should be allowed to jump red lights