Roundabout basics

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ABOUT ROUNDABOUTS


Roundabouts are common in Australia including the Northern Territory (especially at Palmerston!). The UK pioneered the modern roundabout, introducing the first one in 1956. America and Europe have since discovered the advantages - America's first roundabout was installed in 1995.
The purpose of roundabouts is to keep traffic flowing safely with minimal disruption, and they can also act as traffic calming devices. Unlike traffic lights, they still operate during a power failure.

The two basic types in the NT are single-lane and two-lane, the number of "entry points" (or exits) can vary between two and five (the classic "2-lane, 4-point" roundabout is described below).
A particularly interesting design in response to a traffic problem at Swindon in the UK is their "magic roundabout". Visit the Roundabout Variations page for this and some local variations from standard roundabout design.
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APPROACHING a ROUNDABOUT


Approach a roundabout at a safe speed that will allow you to observe other traffic, and to stop safely if necessary.
You might think roundabouts are easy to cope with, but learner drivers can find them quite difficult until they get some experience (see the Roundabouts and learner drivers page).
Observe all signs & road markings as you approach, so you can determine which lane to use and how you're going to signal.
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SIGNALLING & LANE USAGE


As you approach a roundabout, mentally divide it into left & right semi-circles.
An exit road on the left side is considered a left-turn, an exit road on the right side is a right-turn, and an exit road which is straight across the roundabout is considered straight-ahead.

 Signalling: 

Driving up to the roundabout, signal as you would for any intersection i.e. left, right, or no signal if going straight-ahead (see above).
Once inside the roundabout though, you should signal left before you leave, see Leaving a Roundabout below.

 Which lane? 

Roads signs and also lane arrows on the road will indicate which lane to use. You MUST obey lane arrows unless there are unusual circumstances e.g. if a lane inside the roundabout is blocked.

Whichever lane you use to enter (left/outside lane or right/inside lane), use the SAME LANE inside the roundabout and also when leaving.
Keep to left of the central island, i.e. travel in a clockwise direction.
Once inside a roundabout don't stop or change lanes unless there is an emergency.


  1. Approach signal: signal left to go left, right to go right, or not at all if you are going to go straight ahead - just as you would for an ordinary intersection.
    If you are going straight ahead, there is no need to signal right at this point.
    Note: signal as you start to slow down for the roundabout, don't wait until you are right at the entrance!
  2. Signalling off (or exit signal): signal left before you leave the roundabout (see below).
  3. Cancel the signal as you leave the roundabout.
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LEAVING a ROUNDABOUT


 Signalling off: 

You should SIGNAL LEFT before leaving a roundabout, and switch the signal off as soon as you have left (Australian Road Rule No. 118).
Signal as soon as possible to ensure you give other drivers adequate notice of your intention to leave, but not so soon as to confuse. When going straight ahead, the best time to give the exit signal is when you are half-way across the roundabout - any sooner you are giving a confusing signal, any later the signal has no value.

 Why give an exit signal? 

There are two good reasons why you should signal off:
  1. It allows drivers entering the roundabout on your right to make an informed decision if it's safe to enter the straight away (i.e. you are leaving the roundabout before you reach them).
    Roundabouts are meant to keep traffic flowing! It disappoints me how many NT drivers will complain when other drivers hold them up, but don't themselves consider other drivers by signalling when leaving a roundabout.
  2. In a 2-lane roundabout it benefits cars behind you when you are leaving from the inside lane.
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PEDESTRIANS, CYCLISTS & HORSE RIDERS

 Pedestrians 

Pedestrian crossings are usually provided at roundabout entry points.
Use these to cross, as walking in or across roundabouts is very hazardous.

Drivers using roundabouts should be on the alert for pedestrians - and cyclists too (see right).
 Cyclists and animal riders 

If you must ride in a roundabout, use the outside (left) lane, be very careful of other traffic, and always give way to vehicles which are leaving the roundabout.

Australian Road Rule 119: "The rider of a bicycle or animal who is riding in the far left marked lane of a roundabout with room for 2 or more lines of traffic (other than motor bikes, bicycles, motorised wheelchairs or animals), or the far left line of traffic in a roundabout with 2 or more lines of traffic, must give way to any vehicle leaving the roundabout. Offence provision"
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ROUNDABOUT SIGNS


You are approaching a roundabout.

Lane usage (same info is provided with road arrows in each entry lane).

Regulatory sign at the entrance, identifies the intersection as a roundabout.
Some more signs used at 2-lane roundabouts (in this case, a T-intersection roundabout in Palmerston at the intersection of Chung Wah Terrace and Lambrick Avenue.

See the Roundabout Variations page for more info on this particular intersection).
This style of information sign helps you locate the exit you require, and also helps you choose the correct lanes to use as you approach, in conjunction with the lane usage signs and road arrows - e.g.
  • Exit road is on the "left semi-circle" - signal left, prepare to use the left lane unless signage dictates otherwise, and signal left before leaving the roundabout.
    (Note: if taking Exit 2 in the 2nd diagram, you would delay your signal until you are passing Exit 1, otherwise you could fool a driver emerging from Exit 1 to pull out in front of you.
  • Exit road is on the "right semi-circle" - signal right, prepare to use the right lane unless signage dictates otherwise, and signal left before leaving the roundabout.
  • Exit road is substantially straight ahead - do not signal as you approach the roundabout, observe lane usage signs and road arrows to pick the correct lane(s), and signal left before leaving the roundabout.
What does the "gap" in the circle mean?

It is to remind drivers to circle the roundabout in a clockwise direction.
You read the sign from the bottom up (as you do with all road-layout signs), a visitor from overseas thinking of entering to the right of the island should note the gap and be reminded to enter to the left.
It also helps to orient yourself in relation to the sign as you search the circle with your eyes for your exit.

Is the gap a barrier?
Only if you enter the roundabout in the wrong direction.
It isn't a barrier if you circle the island correctly (clockwise), and provided you follow the rules on signalling & lane use, you can "loop" the roundabout as many times as you wish (e.g. you are lost!).
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