Contents:

Overview: What is Ramp Signalling? | When, how & why does it function?

Section Two: Questions & Answers

Section Three: Detailed description of Ramp Signalling function | Locations in Auckland

Section Four: Results | International Usage | Video explanation | Criticism

Feedback Section: Vote on what you think | Comment | Read Comments

What is Ramp Signalling?

Layman's terms: Traffic is drip fed onto the motorway at on-ramps to prevent and/or lessen congestion caused by excess demand.

Technical Language: Ramp Signalling is the process in which on-ramp demand is regulated before it can enter the motorway, so that motorway traffic is kept at a more constant rate. The technical name for Ramp Signalling is Traffic Demand Management (TDM).

Ramp Signalling means that vehicles have to wait at on-ramps until they are allowed to enter the stream of traffic at a determined rate. Ramp signalling can prevent congestion from being severe in certain locations which allows more consistent speeds over the length of a motorway.

At an on-ramp: Ramp signalling at an on-ramp functions by regulating how many vehicles can enter at one time. This has two effects: one; traffic on the on-ramp enters at an even pace, allowing easier merging with motorway traffic. Two; traffic on the motorway can adapt and handle the traffic entering from the on-ramp far better, and means traffic will merge easier and far safer. On the overall network: If all on-ramps on the network are regulated then traffic is more likely to travel at one continuous speed, as traffic entering the motorway is managed to the volume of the motorway versus the volume of the on-ramp. Therefore speeds are more constant, travel times are more reliable and it is safer when merging with other vehicles.

When, how and why does it function?

When: Ramp Signalling is usually switched on during peak periods - at all or some on-ramps depending on the conditions. Ramp signalling, due to the sensors at on-ramps and motorway itself, have the ability to turn on automatically at other times also, like interpeak or other busy periods.

It may be used at or during:
- Isolated areas that cause congestion e.g. Pukekohe on-ramp on the Southern Motorway.
- Continuous large volume ramps like the southbound Grafton Gully on-ramp on the Southern Motorway - or throughout CMJ Spaghetti Junction.
- Ramps surrounding an incident area to alleviate congestion.
- After shows or events out of peak times. E.g. Greenlane expo area, at Greenlane on-ramps or St Lukes for Eden Park.

How: When Ramp Signalling is switched on it will allow one car per lane per green light and cars stop per red light. The red light may stay on from one to ten seconds depending on the conditions. For more information on how the lights work in detail have a look below.

Why: Congestion is caused on the motorway when there is too much demand in a certain section of motorway. This can occur where an on-ramp is located because traffic from the on-ramp comes in bursts or extended high demand or an area of motorway where traffic has congested. Ramp Signals manage this demand, by allowing traffic to enter at regulated rates, where effects of high demand are mitigated or even avoided.

Positives from Ramp Signalling:

- Can prevent clusters or bursts of traffic causing irreversible traffic congestion on the motorway. Prevents congestion.
- Can decrease peak period length and congestion severity. Shorter peak period.
- Adapts to changing traffic levels (which adjusts the level of managed flow) which assists travel time predictability. Allows more predictable journeys.
- Encourages better and more compatible merging behaviour.
- Gives priority to trucks, HOV's[?] and buses.
- Discourages short journeys or usage of ramps that cannot handle high volumes of traffic. (Like Wellington Street on-ramp).

Negatives from Ramp Signalling:

- Waiting at on-ramps.
- Some journeys may save time on the motorway but time is lost waiting at the signals.
- A trip was once efficient, now inefficient.
- Can increase rat running.
- Expense from installation could have been spent on widening certain sections instead.

Won't this cause more congestion and take even longer?

Ramp Signals do remove the freedom for the driver to just enter the ramp at will, in some cases on-ramps will cause queues back onto the streets that were used to access them. The congestion caused from the ramp signals (at the ramp) is a necessary side-effect in order to achieve better speeds, improved merging and congestion mitigation. Queues usually stay at a constant length in most cases.

Ramp Signalling is only used during peak periods, or when motorway traffic is bad enough. If waiting at the lights takes a long time, then journeys may need to be changed, or the time they are made may need to be altered.

What if I'm carpooling, in a bus or in a service vehicle?

There are exceptions at certain on-ramps where HOVs[?] (High Occupancy Vehicles i.e. more than two/carpoolers), trucks and buses are allowed to enter the motorway without having to queue. Have a look at the locations below for a list of ramps that have priority lanes.

Above: HOV, Bus & Truck lane where signals do not apply. Taken at the SEART northbound on-ramp.

Why is Ramp Signalling installed far along the motorway, away from areas that are usually un-congested at peak periods?

In order for Ramp Signalling to reach its full potential signals need to be applied along the length of the whole network or at least within the vicinity of congestion.

If Ramp Signals are only applied to ramps in a certain section then traffic is able to move through those certain sections faster, however this traffic is now able to get to the next congestion spot quicker and will cause congestion there. This is called Induced Congestion. This happened when signals were first installed in Auckland. Congestion through Spaghetti Junction was relieved somewhat but then traffic congested around Greenlane - so Ramp Signalling needed to be installed at Greenlane to address the issue.

A byproduct of installing across a whole network is that waiting times at on-ramps will reduce. This is because certain signals now do not have to regulate at such a high level to compensate for other unregulated ramps.

Why are Ramp Signals installed on on-ramps with dedicated lanes (lanes that do not merge with the motorway)?

The idea of Ramp Signalling is not to just help merging, but help the flow along the whole motorway. If all ramps are in sequence the whole project will work more effectively. Although dedicated lanes do not merge directly with motorway traffic they still contribute large volumes of traffic (see volumes in the glossary), that is why they have their own lane.

Some examples of dedicated lanes with ramp signalling are the Mt Wellington, Greenlane and Hobson Street on-ramps.

What is the point of Ramp Signalling when I only move a few metres when the lights change? (i.e. when traffic is really bad).

The signals can seem pointless and ineffective when the traffic is so bad that when given a green you only move a few metres ahead - or not at all. This usually occurs at the most congested time period in a certain section.

Remember that Ramp Signals will not prevent congestion from happening altogether, they are designed to manage flow either by preventing the congestion totally, limiting severe congestion or helping to get rid of congestion faster. At some on-ramps (which have queue detectors fitted) the signals will switch off and be turned back on when the queues have shortened.

Why don't Ramp Signals make congestion disappear all together, and if they can't what is the point?

Ramp Signals will try and prevent congestion from occurring as much as they can, but Ramp Signals cannot stop traffic entering the motorway completely. If preventing congestion fails Ramp Signals will then help alleviate congestion.

Ramp Signals do this by managing the flow of traffic entering the motorway, therefore allowing traffic on the motorway to clear quicker, thus shortening the peak period and severity of congestion. Have a look at the graphic below, which illustrates the difference between a peak periods with and without signals:

The graphic above highlights that if Ramp Signalling runs (blue) between a certain period, in this case the afternoon peak, it does the following:

• Shortens the heavy traffic period (yellow).
• Lessens the length and intensity of the congested period (red).
• Shortens the overall afternoon peak periods so that between 3-4pm and 6.15-7pm traffic is moderate or free flowing (blue).

It has this effect because Ramp Signals will run before traffic is congested - therefore congestion will occur later, at lower levels or not at all.

Why is Ramp Signalling running when there is no traffic on the motorway or anywhere ahead of where I just got on?

Sometimes you may encounter the signals running at an on-ramp where there is fast moving traffic on the adjacent motorway or once you get on there is no congestion ahead.

This occurs because:

• There is still large demand at the on-ramp and if that traffic was all released then congestion on the motorway may occur.
• There may be traffic on the motorway further back from the ramp, signals will still run to allow this congestion to clear over the whole network.
• When you were entering the motorway there may have been a congestion patch either ahead or further back. Ramp Signals will run until this congestion is alleviated (or minimised) before turning Ramp Signals off. This can mean you were in the Ramp Signal queue just before the signals were turned off.

Remember, if you are entering at an on-ramp and you find there is no congestion next to your ramp (on the motorway) do not think that the signals are not working properly. They have identified congestion somewhere on the network (usually ahead) and are working to try and alleviate this.

'One vehicle per green per lane' is confusing and what should I do when I am the only car coming up to changing lights?

'One vehicle per green per lane' means that one car may move off in each lane whenever the light changes to green. 'Per Green' does not mean if there are four sets of green lights that four cars can move off. 'Per green' means each cycle of the lights from red to green, therefore one car per lane moves off when it goes green.

If you are the only car approaching the traffic lights and they are cycling between red and green you do not need to stop if you are the first or only car coming up to the lights. However, if you are in a group of cars approaching an empty ramp then unless you are the first car or first two cars (depending on the ramp configuration) you will need to slow down and stop. For example if you are the fifth car in a group of six cars approaching an empty two lane ramp then the first two can go through and the next set of two must wait their turn.

Stuff waiting, can I just drive through?

Running a red Ramp Signal is exactly the same as running through a red at an intersection, the thing to remember is every on-ramp is monitored and runners are more likely to be fined. The same applies for people zooming through on the carpool/truck/bus lanes when they shouldn't be. Don't be worried if you miss the signal because the timing is too quick - the warning is designed for people who drive through the lights with the intent of not stopping at all.

Detailed description of Ramp Signalling function

Ramp Signals take in various sorts of data; the already recorded traffic flows and volumes of the motorway, time periods of demand, volume on the motorway at current time, volume on the on-ramp and a manual set up. It uses this data to decide when to turn on and off and how long the phases are for. Have a look at the graphic below for an illustration:

The above scenario may only run for a couple of minutes because the signals are constantly assessing the demand from all the sensors. The volume on the motorway may decrease, therefore the Ramp Signals can allow a greater percentage of the total demand through.

In the above scenario this is how the signals determine how much time to give at the lights:

If 750 vehicles are allowed through per hour then: 750veh. / 60min. = 12.5 vehicles per minute are allowed through therefore 60sec. / 12.5veh. = 4.8.
So every 4.8 seconds a vehicle is allowed through.

Remember that 'per hour' only means an hour scenario right at that precise time for the calculations to work. It does not mean that the scenario will last an hour. For example five minutes after all these calculations were done the volume on the motorway dropped to 75%. So the full 20% demand for the on-ramp is now allowed to enter the motorway. This means everything is now recalculated: 1500veh. / 60min. = 25 vehicles per minute are allowed through therefore 60sec. / 25veh. = 2.4. So every 2.4 seconds a vehicle is allowed through.

Ramp Signals can reach a saturation point however. If there is far too much demand from the ramp and far too much volume on the motorway Ramp Signals will run at their maximum ten second cycle. Ramp Signals will not hold cars for more than ten seconds at the front of the queue.

When demand is too high Ramp Signals will be ineffective at holding vehicles until the demand drops on its own or from Ramp Signals elsewhere on the network. When demand drops Ramp Signals can achieve an overall faster clarence of congestion by managing demand.

Examples and locations of Ramp Signalling in Auckland

Status: Completed in November 2009

Ramp Signalling has been installed on the whole Auckland Motorway network, with some exceptions. Currently there are seventy ramp signal sites on the Auckland motorway network. Mahunga Drive was the first on-ramp to have signals installed, where a trial was conducted.

Ramp Signalling has been installed throughout CMJ (Spaghetti Junction) with Grafton Gully being the only ramp with priority lanes there.
Along the length of the Southern Motorway with priority lanes at Mt Wellington and SEART on-ramps.
The North Western Motorway with priority lanes at Te Atatu and Waterview.
On the Northern Motorway with priority lanes at Upper Harbour/Constellation Drive and Greville Road.
And the South Western Motorway at Hillsborough Road, Dominion Road, Mahunga Drive and Neilson Street. The South Western to Southern motorway link Southbound at Manukau has Ramp Signalling installed at three lanes wide.

Notable on-ramps without Ramp Signalling include the Onewa Road and Fanshawe Street on-ramps.

Greenlane northbound Ramp Signalling, two lanes of traffic	Hobson Street Ramp Signalling, two lanes of traffic
Symonds Street Ramp Signalling, only one lane, and only one set of lights on the right side.	Khyber Pass Ramp Signalling.
North Western to Northern Ramp Signals, two lanes. More Images	Waterview eastbound Ramp Signals with priority lanes on the North Western Motorway.
Curran Street Ramp Signals, two lanes, slows congestion on the Harbour Bridge.	Wellington Street Ramp Signals in action, single lane.

Results

With Ramp Signalling now being fully installed Auckland wide effects from Ramp Signalling are starting to prove some positive results.

So far results include:

• So far there is a 30 to 50 minute reduction in the peak period congestion.
• 600-650 more cars are getting through sections compared to before and average speeds have increased from 25 km/h to 60 km/h (CMJ).
• Trials on Gillies Ave have noticed a 8 to 12km/h improvement in speeds on the motorway (CMJ).
• For the whole network there is a 15% increase in travel speeds, a 15% increase in vehicle throughput, a 24% reduction in incidents, a 91% improvement in the reliability of travel times and a reduction in emissions of 54,500kg per day (nine petrol tankers per week).

Between Grafton and Symonds Street 2006 at 6.30pm	Between Symonds and Grafton 2007 at 6.30pm

International Usage & Trial

Ramp Signalling is used worldwide, it has successfully been used for over 40 years in some cities in the United States; Australia has Ramp Signalling in Melbourne, Brisbane & Sydney; in Germany, the Netherlands, Canada, France, Belgium and England. Ramp Signalling is being pushed throughout the EU, installed throughout Japan, trialed in Italy, Israel and the EU. Ramp Signalling has been recognized as a way to tackle and ease congestion, but remains controversial. Ramp Signalling was first used in 1963 in Chicago, where a police officer would stand at the end of an on-ramp and regulate the traffic entering the motorway with hand signals.

The implementation of Ramp Signalling in Melbourne has seen a dramatic 70% increase in traffic speed and a 60% reduction in travel times, implementation in Melbourne will continue.

In the United States

In Minneapolis, Minnesota, Ramp Signalling was introduced in the year 2000, the implementation was not well planned, and was not managed for the conditions, the signals were removed. After removal of the signals the following trends were recorded: a 9% reduction in freeway traffic volumes, a 22% increase in travel times, a 7% reduction in speed, a 91% decline in travel time reliability, a 26% increase in crashes and most surveyed commuters believed that traffic worsened without the signals. Ramp Signals were re-installed in 2002 with proper management and careful implementation. It is now a success.

In the United States alone there are 2,200 Ramp Signals running, Ramp Signalling has been used successfully there since the 1960s. Some locations such as Austin, Dallas, San Antonio and Columbus Ohio have turned off Ramp Signalling permanently after unsuccessful trials, however some have been turned back on. Ramp Signalling has been used in some cities in Europe since the 1980s. Ramp Signalling in Canada is only used in a small section of the Queen Elizabeth Way in Ontario, Ramp Signalling there has a different system of shutting signals down once it backs onto city streets. These signals average on a 5 to 6 second wait for one vehicle to enter the motorway.

Ramp Signalling can also be used differently as Mainline Metering, instead of signalling (metering) an on-ramp - the whole motorway is metered or controlled with speed limits. One section would be set at 60km/h then 500m later it is 80km/h. This is being used in England and has been used in San Francisco since the 1970s on the approach to the Golden Gate bridge to avoid congestion occurring on the bridge itself.

Trials in England showed that peak times finished 20 minutes earlier with Ramp Signalling. But conclusions in England were not too flash, with negative effects taken into account only an average 2 to 7% improvement in flow was achieved, and Ramp Signalling only proved to be effective on highly congested junctions and bottlenecks. It did not prove successful when used outside of junctions or non bottleneck areas. In some cases it proved more cost effective and better for the region to just 'widen the motorway' or 'fixing the bottleneck' with more lanes or addressing the real issue.

Back home the Esmonde Road citybound on-ramp once had ramp signalling installed in the early 1980s as a trial, this system did not work very well as it would hold vehicles for around four minutes then release a large group then hold a group for another four minutes, the system that has been introduced is far more efficient and advanced than this.

Ramp Signalling Videos

Curran Street in Auckland Example of Ramp Signalling in the Netherlands

Criticism

Grafton On-ramp before Ramp Signalling.

So far in Auckland, Ramp Signalling has proven to make a positive difference to the flow of traffic on the motorway - but can come under criticism that it causes longer wait times when entering the motorway. The most controversial on-ramp is the North Western to Northern on-ramp. Traffic can tail to such a significant length that using this connection can be a major mistake if you want to complete your journey in a decent amount of time.

Esmonde Road citybound on-ramp has queue detection and will switch the signals off during a certain period of the peak because traffic demand is too high.

Another issue which relates to the on-ramps design is the length from the signals to the motorway. Some on-ramps like Wellington Street have such short gaps between the signals and the motorway that a suitable merging speed cannot be reached. This problem can cause more congestion and renders Ramp Signals useless. This issue can be solved by placing ramp signalling further away from the motorway, by extending the on-ramp or not installing ramp signals at the specific on-ramp at all.

Ramp Signals can also face criticism because of the money spent on installing and maintaining the system could have been spent on widening the motorway. This criticism can fall flat because widening the motorway in certain sections can induce congestion elsewhere thus needing Ramp Signalling to solve this problem. (For example at Greenlane on-ramp southbound).

Vote on what you think about Ramp Signalling

Ramp Signalling is a good idea. Ramp Signalling is a bad idea. Please do not vote more than once, it will cancel your original vote.

Comments

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From: Robert | The installation of ramp signals has certainly added to congestion and the implementation is poorly done. I work at 650 Great South Road in Penrose and now the 'rush hour' congestion starts earlier and lasts over 1hr longer. Our building entrance/exit is 700M away from the motorway on ramp but is now often blocked by traffic queued back from the motorway. The light positioning on the north bound ramp now makes traffic merge onto the motorway at a much reduced speed to the small run-up you now get - a noticeable drop of around 20kmh. The proliferation of lights on the Mt Wellington highway now creates worse queues back on the southern well back past the Panama road over bridge creating a hazard at the brow of the hill. If I now need to travel across Auckland some of my travel times are tripled as the queued traffic back from the southern motorway stop me going east\west. An example of going from lower Penrose to Sylvia Park is a jump in time of around 10 minutes to over 1/2 an hour. A trip I used to regularly make from Wyndham St to Penrose that would often take 25 minutes jumped to 40 minutes using the motorway. But I quickly found that doing a rat run of domestic streets dropped this to around 20 minutes. The current policy of lights everywhere is creating pollution & grid locking the city.

From: Les | I just cannot believe that those who installed the dual on ramp lights have the greens going at the same time instead of alternately. This is absolutely crazy because it has two vehicles making a b line to one lane; hence setting up a sometimes agro 'who is going to get there first' burn off scenario.  I have experienced this lighting set up many times in the US and the lights always flash alternately so as to avoid this situation. I have also experienced the burn off here.

Answer: I believe they do not have different light phases for each lane primarily out of confusion. I have spoken to people that find the concept of one car going through per green per lane challenging enough. Having two lanes going at different times would probably make matters more confusing. People that partake in the ‘burnoff’ do this by choice, if the person in the car next to you decides to use half a tank of petrol just to beat you then you could just cruise off and let them make a fool of themselves. I have taken part in a burnoff before, it was quite fun.

From: John | The proposed ramp signals to the citybound on ramp at Tristram Ave go against the idea of helping to merge traffic. The onramp at Tristram does not merge, it is in fact the start of the 3rd lane to the bridge. All the signalling is going to do is create gridlock in Wairau Rd and Tristram and add God only knows how much extra traveling time to an already difficult journey. This is madness!!

Answer: The goal of ramp signalling is not just to assist merging, but to assist flows on the whole motorway. Yes Tristram enters on a dedicated lane, but this does not mean it is free from affecting other motorway traffic. Despite being the beginning of the third lane on the bridge (eventually) it also shares merging with Northcote and Esmonde Road.

From: Warren | The benefits from ramp metering (ramp signalling) depend on where a user is. Waiting at the on-ramp or traveling on the motorway. There is one point where they meet and that is the critical point for success or congestion on the motorway. In the case of Wellington Street, where there is a relatively short merge distance before the restriction at the start of Victoria Park Viaduct. Ramp users can help themselves by adjusting their speed to that of vehicles on the motorway. It they speed up and force themselves into a gap, then the speed of the flow on the motorway must drop to allow the eager driver to get in. This slow down causes a "shock-wave" that travels back along the flow of traffic and as a consequence the spacing between vehicles decreases. This then decreases the gap for ramp traffic to move into, that again reduces the motorway speed even further. Next time readers use this; and other ramps with "metering", note what is happening. Before the start of Victoria Park Viaduct there is as slow down of all traffic as ramp traffic races to the end of the ramp and squeezes into the left lane of the motorway.
After, the traffic flow starts to speed up. Users can assist by holding back the urge to get to the merge point at speed and simply adjust to the motorway speed. What is the benefit? Everyone will benefit by not having to wait as long in the queue to enter the motorway.  Try it, it works and you can contribute to the well being of your fellow daily travelers.

From: Alistair | I enter the motorway at Wellington Street, from the CBD. It used to take me 10 minutes to get onto the motorway, and then 30 minutes to get home, total 40 minutes. Now it takes 30 minutes to get on the motorway, and 25 minutes to get home, total 55 minutes. So my journey home has been increased by 15 minutes because of the ramp signals. I think the ramp signals are unbalanced, and cause too much delay before entering the motorway, with an insufficient gain in traveling time, once actually on the motorway.

Answer From: Ben | Just One thing to note, in your vicinity and your journey only 3 ramps have ramp signalling installed, the North Western to Northern, The Wellington Street and Curran St on-ramps. Once ramp signalling is installed on all chosen ramps along the Southern and Northern Motorways you will notice a significant difference and have to wait less at the on-ramp. Currently the ramp signalling at Wellington Street has been installed because of the temporary lane layouts through this area, and high amount of merging from North Western & Wellington Street. The ramp signalling is planned to be removed when it has its own lane with the new Victoria Viaduct northbound tunnel. I see the trial flaws in Ramp Signalling, but it’s too early to give up on it. As you mentioned ramp signalling has made a difference to your journey time on the motorway then it means that ramp signalling is working. This time can only get shorter and with more even flowing traffic on the motorway, ramp signalling times will be shorter due to faster flows.

From: Chris | While ramps signalling may ease congestion ON the motorway it appears to be causing longer than usual delays/traffic jams for people waiting to get on the motorway.  I usually enter the northbound Northern Motorway at Wellington Street but since the ramp signals have been installed I find it quicker (and more economical) to travel further through Auckland City and get on at Fanshawe Street.  Surely this could not have been what was intended.

From: John | Hong Kong uses it on one its busiest sections which is only two lanes each direction and cannot be widened due to the buildings around it, seems to work quite nicely.