Three-arm roundabout
Three arms in a T. From the side road the second exit is a right turn, on the main road the first exit can be straight ahead, and the signal follows the direction every time.
Signal for the direction, not the number
The Highway Code ties the signal to where you are going: left for a left turn, right for a right turn, nothing on the way in for straight ahead. On a four-arm roundabout the second exit happens to be straight ahead, which is how "second exit, no signal" becomes a habit. Here, coming out of the side road, the second exit is a right turn. It needs a right signal on approach, then a left signal once you have passed the first exit.
When straight ahead is the first exit
Along the main road in one direction, the road ahead is the very first exit. There is no exit to pass before yours, so the left signal goes on as you join the roundabout. The other way, straight ahead is the second exit and the side road is the first. Same junction, two different counts, which is why the clock is a better guide than the number.
The traffic is the same every time
Every scenario runs from a fixed seed at a fixed timestep, so the cars arrive in the same order at the same speeds on every attempt. Waiting to pull out of a side road into busy main-road traffic is a decision you can repeat until it is automatic.
Common questions
Which exit is straight ahead?
It depends on where you come from. From the side road there is no straight ahead: the first exit is left and the second is right. On the main road, straight ahead is the first exit one way and the second exit the other.
Do I still give way to the right?
Yes. Three arms or six, traffic already on the roundabout coming from your right goes first.
The rest of the set
- Single-lane roundaboutFour arms, one lane round. Give way to the right, take the second exit.
- Mini roundaboutPainted island, same priority rules, and you still have to go round it.
- Double mini roundaboutTwo minis, one after the other. Each is its own give way. Read them one at a time.
- Two-lane roundaboutTwo lanes round, spiral arrows on the road. Right lane and a right signal for the third exit.
- Signal-controlled roundaboutLights on every arm. Green gets you to the line: you still give way to the roundabout.
- City gyratorySix arms, two lanes, uneven spacing. One arm only joins and one only leaves. Count carefully.
- Magic roundaboutFive minis around a ring that runs the other way. Read them one at a time and it is just five give ways.
Also included: the manoeuvre simulator and the 3D drives of the routes around your own test centre.