Signals and Road Markings
Signals
Traffic signals control competing movements. A steady red means stop before the stop line; amber means stop unless you are so close that stopping safely is impossible; green means proceed if the way is clear. A green arrow permits only the movement shown. Flashing amber warns of a hazard or uncontrolled junction; flashing red (where used) means stop and proceed only when safe. Police or authorised officer signals override traffic lights and signs.
Road markings
Markings reinforce signals and signs. A solid white centre line means no crossing or overtaking; a broken white line permits overtaking when safe. A double solid line forbids crossing from either side. Stop lines mark where you must halt at a stop sign or red light. Give-way lines (broken) mark where you yield. Edge lines define the carriageway. Zebra crossings are marked by broad white stripes; pedestrians on them have priority. Yellow lines near the kerb indicate parking restrictions.
Traps in questions
Questions often test the amber light: it does not mean "speed up." Another trap is the difference between a give-way line and a stop line, and whether a solid line may ever be crossed (generally only to enter premises or avoid an obstruction, where the law permits). Watch for markings that conflict with a temporary sign; the temporary control prevails.
Rule of thumb
Solid = do not cross; broken = cross with care. Amber = prepare to stop, not to accelerate.
Worked example
Approaching a junction with a broken give-way line and a clear road ahead, you slow, check both directions, and proceed only when safe. If the line were solid with a STOP sign, you must come to a complete stop first, even if the road looks clear.