Ramp signals FAQs

Is ramp metering only about improving the ramp merge?

Using ramp signals to break up the bunching of vehicles on a ramp makes it easier to merge. This will help traffic enter the motorway. Operating the ramp signals as a coordinated system will also assist in limiting excess traffic arriving at downstream bottlenecks some distance away. Coordinated ramp signals provide wider benefits for overall motorway performance. 

Does ramp metering reduce ramp flow and cause increased delays?

A small delay shared across a number of ramps results in more reliable motorway journeys, shorter travel times and more traffic using the motorway. This is because:

• When freeways are allowed to become congested, less traffic gets through, delays for all motorists increase significantly and less traffic is able to enter the system.
• Excessive ramp queues are usually a result of the motorway being allowed to breakdown due to large increases in traffic trying to use the motorway. Ramp metering tries to help the motorway recover to stable flow while also managing ramp queues.
• When motorway flows are maintained, without breaking down, more traffic can enter so ramp flows can be higher, even when metering is in operation.

Why do the ramp signals need to be on when the motorway is flowing at a reasonable speed?

A well-managed motorway may look relatively ‘empty’ with good speeds and light traffic conditions, as traffic is kept moving.  When a motorway starts to become unstable it is usually too late to intervene. The ramp signals may be on because:

• Events that lead to flow breakdown can occur very quickly (often in less than a minute) - instability may also occur at relatively moderate flows.
• There may be a need to manage a traffic problem further downstream from the metered ramp and nearby merge. 

Do drivers need to stop on the red signal if there is no obvious congestion on the motorway?

Ramp metering signals are normal traffic lights so motorists must stop on the red signal and then wait for a green light. Drivers need to travel at an appropriate speed when using the ramp for the safety of all traffic.

Why don't ramp metering signals alternate for each lane, as used overseas?

Releasing vehicles together provides greater ramp discharge and more operational flexibility.  Some road agencies overseas need to release vehicles in each lane separately as their design standards provide minimal space for merging on the ramp. Australian ramp metering design standards, for merging and acceleration, provide safe operation with vehicles leaving together.

Why is there congestion if ramp signals are operating?

In the real world it is not always possible to prevent congestion, but if it is to occur, it can be delayed to minimise impact. A well-designed and operated system will minimise the flow breakdown potential and improve safety. Even when congestion does occur, measured outcomes show that continuing to meter traffic still results in better flows than if they were switched off.

Why can't a full ramp queue be flushed to avoid overflow onto the arterial road?

Operations need to balance needs and priorities according to safe and efficient principles because:

• Sudden ramp flushing generally worsens motorway safety, throughput and delays. Dumping traffic into the motorway could potentially have worse safety outcomes than queuing on the arterial road.
• Just a few too many vehicles from a ramp can cause flow breakdown which would impact thousands of motorway travellers for the rest of the peak period.

The system aims to manage queues in a safe and regulated manner within the ramp length, discharging traffic without exceeding motorway capacity. Balancing of queues and waiting times are also used across the coordinated ramps.

Is there enough distance provided for acceleration and merging?

The standards for acceleration and merging on the ramp, and when entering the motorway, meet national design standards and provide for safe operation. Different lengths for accelerating and merging also account for the different number of lanes at the various ramp metering sites.

Motorists already on the motorway also need to cooperate and assist merging by making space for others to enter. 

Does a ramp need to be metered if it enters as an added lane?

Coordinated ramp metering is about managing bottlenecks along the whole motorway, not just near a ramp. Effective control requires all ramps to be controlled. Just one uncontrolled ramp can cause flow breakdown and congestion.

When vehicles are already within the motorway system, do motorway-to-motorway ramps need metering?

All vehicles entering a managed route must be controlled to manage the motorway operation. Motorway-to-motorway ramps are generally high volume ramps which can easily cause flow breakdown and impact other downstream traffic flow.  

What are motorway to motorway ramp signals?

Our motorway to motorway ramp signals operate in a similar way, controlling traffic flow when large volumes of traffic from two different motorways meet. The traffic signals help space out vehicles, making merging safer and faster, resulting in less congestion and fewer collisions. 

How do the motorway to motorway ramp signals work?

Motorway to motorway ramp metering regulates the flow of traffic onto a motorway by releasing traffic onto the motorway at appropriate intervals.

Electronic message signs on the ramp let you know when motorway ramp signals are operational.

When the system is initially activated:

• The yellow signal will flash for around 15 seconds.
• The traffic signals will then turn red and drivers on the entry ramp must stop.
• The traffic signals will then turn green long enough to allow one vehicle in each lane to join the motorway traffic.
• The traffic signals will then turn yellow and then red.
• The traffic signals will continue to switch between green, yellow and red to manage the motorway flow.

Only one vehicle in each lane can enter the motorway on a green signal which creates more space between vehicles joining the motorway and results in safer and easier merging with the motorway traffic.

The signals don’t operate all the time. Sensors in the road collect data like traffic volume and congestion so the system switches on automatically during heavy traffic periods such as peak period.

Where are the motorway to motorway ramp signals being located?

The locations where motorway to motorway signals are being used to manage traffic include:

• CityLink to the West Gate Freeway
• West Gate Freeway city-bound to CityLink airport-bound
• M80 Ring Road Greensborough-bound to Calder Freeway city-bound
• M80 Ring Road Greensborough-bound to Tullamarine Freeway airport-bound
• M80 Ring Road Altona-bound to Tullamarine Freeway airport-bound
• M80 Ring Road Altona-bound to Tullamarine Freeway city-bound
• Calder Freeway city-bound to M80 Ring Road Greensborough-bound
• Calder Freeway outbound to M80 Ring Road Altona-bound
• EastLink in each direction to Monash Freeway

What should I do when the signals are on?

The traffic signals at motorway merge points operate like regular traffic lights, but the cycle is much shorter. Be sure to stop as usual at the red light and go when the light turns green.

The typical cycle time at a stop line will vary between 5 seconds and 18 seconds, depending on motorway conditions. When traffic flow along the motorway is high, you may need to wait longer before entering that motorway.

Once you’ve passed the ramp signals, you can speed up as you merge onto the motorway.

Further detailed reading is also available in the various Traffic engineering manuals.