How traffic lights work

About traffic signals

Learn about the history of traffic signals, how they’ve evolved and the local phenomena of hook turns.


History

The world's first traffic signals began operating on 5 August 1914 on the corner of Euclid Avenue and East 105th Street in Cleveland, Ohio, USA.

Melbourne’s first were installed as a trial by the Melbourne City Council at the intersection of Swanston and Flinders Street in 1928. These were manually operated, but were used for only 1 year.

In 1929, mechanically and manually controlled traffic signals were placed at the corner of Swanston Street and Collins Street.

Marshalite clocks

Marshalite clocks or signals were a different form of traffic signals designed by Charles Marshall.

The Marshalite signal consisted of dials facing each street at an intersection, with a rotating hand pointing to green, yellow and red coloured sections.

The first experimental model was erected in 1937 at the corner of Gertrude and Brunswick Street, Fitzroy, but was later removed when its legality came into question.

After 1945, Marshalite signals were installed around metropolitan Melbourne, starting with the intersection of Brunswick and Johnston Street in Fitzroy.

Marshalites continued to operate at some intersections along the Nepean Highway until the 1970s.

Signal displays

Photo of a traffic light showing a green light

Signal displays work by alternating the right of way by standardised coloured lights.

  • Green = go
  • Red = stop
  • Yellow = stop if safe to do so

Arrow displays indicate which turns have right of way. When no arrow is displayed, you may turn when indicated by the circle display but must give way to oncoming traffic and pedestrians. 

Displays for other modes

Pedestrian crossing lights with green man showing

Pedestrians are controlled by a green walk display and a red standing display.  

When the display is green, you may start to cross.  When the red display is flashing, it means that you must not start to cross but you may complete your crossing to the centre refuge island or the opposite kerb – whatever comes first.  

For off-road cyclists, you are permitted to ride across if bicycle displays are provided at the crossing, otherwise you must dismount and walk across with your bike.  For on-road cyclists, if bicycle displays are provided, then you must abide by them.    

There are also:

  • T-displays for trams 
  • B-displays for buses 
  • E-displays for emergency vehicles 

T, B and E displays are special displays in that instead of green to indicate ‘go’, they are white.

Hook turns

Hook turn traffic sign

Melbourne is known for the rather unusual ‘hook turn’ where drivers turn right from the left lane.

When you see the sign (pictured above), drivers must approach in the left lane and wait on the left side of the road within the intersection until the lights go green for the direction they intend to turn into.

Hook turns are primarily implemented in Melbourne’s CBD and inner suburbs to keep intersections clear for trams.

Learn more about hook turns here.