Green Light, Full Box, Amber Lamp
At 17:30 on a weekday you are approaching a four-lane signal-controlled junction in Port Harcourt in the left-hand lane at about 40 km/h. The light is green. Beyond the junction the road is queued nose-to-tail, and the yellow box grid painted across the junction already holds four stationary cars. A pedestrian has just stepped onto the zebra crossing between you and the stop line, walking left to right. As you close to within 10 metres of the stop line the light turns amber. In the mirror a minibus is close behind, and its driver has begun to edge out as if to follow you through.
1. The light is green but the far side of the junction is full. Do you enter the box? Explain.
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No. A yellow box grid means do not enter unless your exit is clear. The green light permits you to cross the junction; it does not compel you to enter a space you cannot leave, and it does not override the marking.
Four cars are already stationary on the grid. If you follow them you will stop inside the box, and when the lights change you will block the cross traffic that now has green, as well as the pedestrian route across the junction. That is precisely the gridlock the marking exists to prevent - one blocked box in a rush hour junction propagates backwards through several approaches.
So you hold behind the stop line with the green showing, leaving the box clear, and move off only when there is room on the far side to clear the junction completely in one movement.
2. Now the amber and the pedestrian. What do you do, and how do you manage the minibus behind?
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Amber means stop, unless you are so close that stopping would itself be unsafe. At 40 km/h, reaction plus braking needs roughly 15 metres to bring the car to rest; you are 10 metres out, so you are borderline on distance alone. The deciding factor is the pedestrian already on the zebra: you must stop and give way.
So: brake firmly and progressively, keep the wheels straight, do not swerve around the pedestrian, and stop before the stop line.
For the minibus behind: brake early rather than late so your brake lights give maximum warning, and tap the pedal once or twice first. Leave a little extra room in front of you so that if you are struck from behind you are less likely to be shunted onto the crossing. Keep the brake pedal held after stopping. Do not wave the minibus through into a crossing that has a pedestrian on it.
3. A warden waves you forward into the grid while it is still full. What is the correct response?
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An officer or warden's signal outranks the signal head and the markings, so in principle you comply. But compliance is not unconditional: you remain responsible for not endangering people.
Here the direction would take you into an occupied box alongside a zebra crossing with a pedestrian on it. The correct handling is to:
- creep forward slowly, make eye contact with the warden, and gesture that the far side is blocked;
- enter only when there is space to clear the crossing and the box, or when the warden clearly intends to hold the cross traffic for you;
- never accelerate into a blocked box on the strength of a wave alone, and never move off while the pedestrian is still in front of you.
If the warden genuinely needs the space cleared, holding back briefly so the manoeuvre can be done safely serves the same purpose without creating a second obstruction.