4.4 Traffic Circles & Roundabouts
Key Takeaways
In modern roundabouts, traffic travels counter-clockwise around a central island at low design speeds (typically 30–40 km/h), and entering vehicles must yield to traffic already circulating inside.
At a multi-lane roundabout, choose your lane before entering: the left lane is for turning left or going straight, and the right lane is for turning right or going straight; never enter from the right lane to turn left.
Once inside a roundabout, do not stop except to avoid a collision and do not change lanes; if you miss your exit from the inside lane, go around again.
If an emergency vehicle approaches while you are in a roundabout, exit at your intended exit and go past the traffic island before pulling over; if you have not entered yet, pull to the right and wait.
Drivers must signal right as they pass the exit immediately prior to their desired exit to alert other drivers of their departure.
Traffic Circles & Roundabouts
Quick Summary: Modern roundabouts are circular intersections engineered without traffic lights or stop signs, using deflection to enforce low vehicular speeds (typically 30–40 km/h) and counter-clockwise traffic circulation. The golden rule of modern roundabouts is that entering vehicles must yield right-of-way to circulating traffic and crossing pedestrians. Inside the roundabout, do not change lanes, and do not stop for an emergency vehicle until you have exited.
Roundabouts are increasingly replacing traditional signalized and stop-controlled intersections across Ontario municipalities and provincial highway networks (such as Waterloo Region, York Region, Ottawa, and along Highway 26). Modern roundabouts dramatically reduce fatal and severe injury collisions by eliminating head-on and perpendicular T-bone impact angles. Navigating roundabouts smoothly requires understanding lane selection, entry yielding, truck aprons, and exit signalling.
Modern Roundabouts vs. Traditional Traffic Circles
While the terms are often used interchangeably in casual conversation, traffic engineers distinguish between modern roundabouts and older traditional traffic circles:
| Feature | Modern Roundabout | Traditional Traffic Circle |
|---|---|---|
| Right-of-Way Rule | Entering vehicles MUST yield to circulating traffic | Often gave priority to entering traffic (causing gridlock) |
| Design Speed | Low speeds: typically 30 to 40 km/h | Higher speeds: often 50 km/h or higher |
| Entry Geometry | Curved entry (deflection) forces drivers to slow down | Tangential entry allowed cars to enter at high speeds |
| Pedestrian Crossings | Crosswalks located one car-length back at splitter islands | Crosswalks often located directly across circulating lanes |
| Lane Changes | Strictly prohibited inside | Often permitted lane changes inside the circle |
The handbook notes that some older traffic circles still exist in Ontario. They are larger, allow higher speeds and force traffic to merge and weave. Modern roundabouts are smaller, use splitter islands to slow entering traffic, and follow the yield-to-the-left principle: vehicles already circulating have the right-of-way.
[ North Exit ]
| ^
| |
+---------------+
/ ^ \
/ +-----------+ \
[ West ] <=== | | CENTRAL | | <=== [ East ]
Entry | | ISLAND | | Entry
\ +-----------+ /
\ | /
+---------------+
| |
v |
[ South Exit ]
The Golden Rule: Yield Upon Entry
All traffic moves in a single counter-clockwise direction around the central island.
Entering the Roundabout
When approaching a roundabout, drivers face a triangular YIELD sign and a row of painted white yield triangles (shark's teeth) across the entry lane.
- Yield to Pedestrians: First, yield to any pedestrians, wheelchair users, and cyclists crossing the entry lane at the designated pedestrian crosswalk.
- Yield to Circulating Traffic: Second, yield to all vehicles approaching from your left that are already circulating inside the roundabout.
- Find a Safe Gap: Enter only when there is an adequate gap in circulating traffic. Do not enter directly beside a vehicle already in the roundabout, because it may be exiting at the next exit. Cyclists generally keep to the centre of their lane, or dismount and cross as pedestrians.
- Never Stop Inside: Once you have entered the roundabout, you have right-of-way over entering vehicles. You must never stop inside the roundabout to let waiting cars enter; doing so creates rear-end collisions and causes circular gridlock.
Multi-Lane Roundabouts: Lane Selection Before Entry
In a multi-lane roundabout, you must choose your lane BEFORE you enter, exactly as you would when approaching a conventional multi-lane intersection. Overhead destination boards and roadside black-and-white regulatory signs indicate permitted lane movements.
+-------------------------------------------------------------+
| MULTI-LANE ROUNDABOUT LANE RULES |
| RIGHT LANE: |
| - Turn Right (1st Exit) |
| - Proceed Straight Through (2nd Exit) |
| |
| LEFT LANE: |
| - Proceed Straight Through (2nd Exit) |
| - Turn Left (3rd Exit) |
| - Make a Full U-Turn (4th Exit) |
+-------------------------------------------------------------+
Detailed Movements by Lane
1. Turning Right (Taking the First Exit)
- Approach in the right lane.
- Signal right as you approach.
- Maintain the right lane through the curve and exit immediately into the right lane of the cross-street.
2. Proceeding Straight Through (Taking the Second Exit)
- You may approach in either the right lane or the left lane (unless signs indicate otherwise).
- Do not indicate a turn signal upon entering.
- Stay in your selected lane while circulating the central island.
- Signal right as you pass the first exit to announce your departure at the second exit.
3. Turning Left (Taking the Third Exit)
- Approach in the left lane.
- Circulate around the central island in the left lane. (The handbook's required signal is the exit signal described below; some drivers also signal left on approach to show their intention.)
- Signal right as you pass the second exit to indicate you are departing at the third exit.
4. Making a Full U-Turn (Taking the Fourth Exit)
- Approach in the left lane.
- Continue circulating counter-clockwise around the central island until you reach your original road heading in the reverse direction.
- Signal right as you pass the third exit to depart at the fourth exit.
The Strict No-Lane-Change Rule
You must NEVER change lanes inside a roundabout. If you miss your intended exit, do not stop, do not brake abruptly, and do not attempt to cut across adjacent lanes. Simply continue circulating counter-clockwise around the central island a second time until your exit approaches again.
Large Commercial Vehicles and Truck Aprons
Large commercial transport trucks, motor coaches, snowplows, and vehicles towing boat or utility trailers require substantial turning room. Due to off-tracking—where the rear wheels of a long trailer track significantly closer to the inside curb than the cab's steering wheels—large vehicles may straddle both lanes when entering and circulating a roundabout.
+-------------------------------------------------------------+
| TRUCK APRON DESIGN |
| |
| [ Raised Mountable Concrete Lip ] |
| ========================================= |
| [ Grassy / Landscaped Island ] |
+-------------------------------------------------------------+
What Is a Truck Apron?
A truck apron is a raised, red or grey textured concrete curb surrounding the inner perimeter of the central island. It is specifically designed to allow the rear tandem wheels of long semi-trucks to mount the curb without damaging the grass or striking signs.
Rules for Sharing Roundabouts with Trucks
- Never drive alongside a truck: Never enter a multi-lane roundabout side-by-side with a large transport truck or bus. Stay well behind them.
- Give them the full circle: Large commercial trucks may require both lanes to negotiate the circular curve. Allow them to clear the roundabout entirely before entering.
- Do not use truck aprons in passenger cars: Passenger cars, SUVs, and pickup trucks have tight turning radiuses and must stay completely on the asphalt roadway surface; standard passenger vehicles must not mount the truck apron.
Emergency Vehicles in Roundabouts
How drivers respond to an approaching emergency vehicle (police cruiser, ambulance, fire truck) with flashing emergency lights and active sirens depends on their exact physical position relative to the roundabout:
APPROACHING ROUNDABOUT: ======> Pull over to the RIGHT curb and STOP.
Do NOT enter the roundabout.
ALREADY INSIDE ROUNDABOUT: ====> DO NOT STOP INSIDE!
Exit at your intended exit, go past
the island, THEN pull right and STOP.
The Absolute Emergency Rule: NEVER STOP INSIDE A ROUNDABOUT. Stopping inside the circular roadway traps the emergency vehicle behind you, as roundabouts have narrow circulating lanes bordered by curbs and central islands. The handbook's instruction: exit at your intended exit and proceed beyond the traffic island before pulling over. If you have not entered the roundabout yet, pull over to the right if possible and wait until the emergency vehicle has passed.
Signalling Rules for Exiting a Roundabout
Signalling when exiting a roundabout is a vital defensive driving habit that directly improves traffic flow:
- Why exit signals matter: Waiting drivers at the next entrance leg need to know whether an approaching circulating car is going to exit or continue past their entrance. If you do not signal, waiting drivers must remain stopped. If you signal right, they know your car is peeling off, allowing them to enter immediately into the open space.
- When to signal: Activate your right turn signal as you pass the exit immediately preceding your intended exit. For example, if you are departing at Exit 3, turn on your right signal as soon as your vehicle passes Exit 2.
Exiting From the Left Lane
If you exit from the left lane, watch for vehicles on your right that are continuing around the roundabout. Stay in your lane: keep left if you entered from the left lane and right if you entered from the right lane, and keep your position relative to other vehicles.
What is the primary right-of-way rule when approaching and entering a modern roundabout in Ontario?
Entering vehicles have right-of-way; circulating vehicles must yield
Vehicles in the left lane always have priority over circulating traffic
Entering vehicles must yield right-of-way to vehicles already circulating inside and pedestrians crossing
Whichever vehicle approaches at higher speed has the right to enter first
If you are already driving inside a modern roundabout and you hear the siren of an approaching emergency vehicle behind you, what action must you take?
Continue to your intended exit, go past the traffic island, then pull over to the right and stop
Stop immediately inside your circulating lane so the emergency vehicle can pass around you
Accelerate sharply, make an immediate U-turn, and drive against the flow of traffic
Pull directly onto the central island truck apron and stop until the siren passes
In a standard multi-lane roundabout, what movement is a driver approaching in the RIGHT lane legally permitted to make?
Turn left or execute a complete U-turn
Turn left or proceed straight through only
Change lanes into the left lane while circulating the island
Turn right or proceed straight through
What is the purpose of the raised, mountable concrete ring known as a 'truck apron' around the central island of a roundabout?
To serve as a high-speed bypass lane for passenger cars during peak traffic hours
To provide extra turning radius clearance for the rear wheels of large commercial trucks and buses
To designate an emergency waiting zone for broken-down passenger vehicles
To serve as an elevated bike path for cyclists circulating the roundabout
Sections you finish are checked off in the contents.