The sensors for the traffic light is usually just after the white line. If you look closely, you can see darker/black tar lines in rectangular shape. The length of this box would be approximately 80% of the width of the lane. CMIIAW, it is only if your tyres run over such box will they register you as violating - not if your tyres are just (and I mean, just) over the white lines.
If you look closely also, the same dark lines/box can be seen before the white line. Some placed very close, some can be placed quite far. The experts can probably tell you exactly the purpose, but I suspect this is for registering if there are cars on that lane. This is useful if the traffic light is driven (pun intended) by the number of vehicles on the lane. Hence, if they are used for this, the light will not go green unless the lines detect there are cars on the lane.
The sensors for the traffic light is usually just after the white line. If you look closely, you can see darker/black tar lines in rectangular shape. The length of this box would be approximately 80% of the width of the lane. CMIIAW, it is only if your tyres run over such box will they register you as violating - not if your tyres are just (and I mean, just) over the white lines.
If you look closely also, the same dark lines/box can be seen before the white line. Some placed very close, some can be placed quite far. The experts can probably tell you exactly the purpose, but I suspect this is for registering if there are cars on that lane. This is useful if the traffic light is driven (pun intended) by the number of vehicles on the lane. Hence, if they are used for this, the light will not go green unless the lines detect there are cars on the lane.