Olof Lagerkvist wrote:
Earl Purple wrote:

No, the main reason is to eliminate the risk of accidents when people
cross the street in front of the bus before the bus drives away. When
people do so, there is a great risk that a car passing the standing bus
hit the pedestrians. It is a quite common kind of traffic accident in
most countries, especially at bus stops where lots of children go on or
off buses.

Crossing in front of the bus before the bus drives away is a very
stupid thing to do.

In the USA, when a school bus is stopped they sometimes stop all the
traffic around it, a bit over-zealously at times.

One concept (for London buses), if you want to allow the bus to pull
out again, would be to have traffic lights on the back of the bus
itself, thus as the bus needs to pull out the light would go red for
traffic and the bus driver would have his own set of lights and he
would wait for green. These signals would generate automatically with
the bus driver's normal manoeuvres so while the doors are open they
would be green for passing traffic and red for the bus. After it goes
red for the traffic it would wait a few seconds to allow them to
complete the passing manoeuvre but at least the bus would get out
within a few seconds.

If pedestrians want to cross, I guess they could do so safely behind
the bus, once the bus signal goes red. Once the bus pulls out the
signal on the bus will go out.