Contents:

Introduction: What is Ramp Signalling?

Section One: How does it work? | When & how does it function?

Section Two: Frequently Asked Questions: Priority lanes | Cause extra congestion? | Driving through reds | What does 'One vehicle per green each lane' mean? | Questionable install locations | Signals on dedicated lanes | At certain times why does Ramp Signalling not work? | How does the Ramp Signalling technology work?

Section Three: Locations in Auckland | Results

Section Four: International Usage | Video | Criticism

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

What is Ramp Signalling?

Non-technical language: Traffic is slowly drip fed onto the motorway at on-ramps to prevent/lessen congestion caused by excessive traffic.

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 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 the time is right to enter the motorway. This means that traffic is entering the motorway at a controlled rate, where instead of ‘pushing in’ you are let into the main flow of the motorway without causing disruption.

Ramp signalling has two effects: Motorway Speeds are more consistent but it can take longer than it once did to enter the motorway.

What if I'm carpooling, in a bus or in a service vehicle?
There are exceptions at certain on-ramps that are signalled where HOV's[?] (High Occupancy Vehicles i.e. more than two/carpooler's), 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,
with two traffic lanes were signals do apply.
Taken at the SEART northbound on-ramp.

Won't this cause more congestion and take even longer?
In some circumstances you may have to wait at an on-ramp for over two minutes, but instead of waiting in the vicinity of merging traffic at every on-ramp on the motorway you will save time. The key thing to remember is that once you enter the motorway you will have to stop less often than before because of a more controlled motorway system. Note: Ramp Signalling is only used during peak periods, or when motorway traffic is bad enough. If waiting at the lights takes a long time, plan your trip differently, or better still take public transport. Have a look at the results section of this page for information on what ramp signalling is changing.

Stuff waiting, can I just drive through?
Nice try, running a red ramp signal is exactly the same as running through a red at an intersection, the thing to remember though 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. Do not 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.

'One vehicle per green per lane' is confusing, does this mean that if there are four lights, four cars can go at once?
No. '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.

Why is Ramp Signalling installed far along the motorway, away from areas that are usually uncongested 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. Reasons for this apply to a catch-22 of Ramp Signalling - or any other form of traffic alleviation; when you free up traffic in one location it will just congest somewhere else, specifically ahead of the freer location. An example of this is freeing of congestion through Spaghetti Junction through Ramp Signalling meant traffic congested around Greenlane - thus needed addressing with Ramp Signalling at the Greenlane on-ramps. Also Ramp Signalling running over a whole network means that once the whole network is regulated, then waiting times at on-ramps will reduce, because of the regulated flow allowing more volume of traffic. Have a look at the Glossary on Induced Congestion.

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 efficiently. Although dedicated lanes do not merge directly with motorway traffic they still contribute large volumes [?] of traffic, usually very high volumes hence why they have their own lane. Some examples of dedicated lanes with ramp signalling: Mt Wellington, Greenlane and Hobson Street.

What is the point of Ramp Signalling when the lights change, traffic only moves the same as it would without the signals? (i.e. when traffic is really bad)
The signals can become pointless when the traffic is so bad that when you get 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. The ramp signals will not prevent congestion from happening totally, they are designed to manage flow at periods in which it is able to do so. After all, the motorway can only handle a certain amount of traffic and signals cannot stop cars entering the motorway completely. Over time the signals will remember flow periods - and may turn off at these times. Esmonde Road citybound Ramp Signals are an example where traffic will back up too much on the ramp, and flow is too slow on the motorway - the lights will turn off. Have a look at the graphic below:

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 or (rarely) not at all.
• When traffic is free flowing on the motorway - if there is still significant volume on the ramps the signals will still hold them, or allow them to go at faster intervals.
• If ramp signals are having no effect because the motorway is too busy they will either stay on the maximum interval of ten seconds - or not function at all.

Overall Ramp Signals shorten the length and lessen severity of congestion, also the results are fluid, and depend on the demand.

How does Ramp Signalling decide when to turn on and the length of the phases are?
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:

Note the below graphics attempt to outline how Ramp Signalling works, it may not represent the true way that certain Ramp Signals function.

Firstly the signals will want to keep total motorway capacity below a certain level if it can. In the above case it does not want to go higher than 96%. Next it will take the capacity from the motorway before the on-ramp. From that amount it can decide how much it can release - in the above example the motorway is at 86% capacity, so the signals can add another 10%. From the on-ramps demand and how much it can release, the signals will determine how often it can release a vehicle. In the above example the signals can release 700 vehicles per hour = 11 vehicles per minute = 5 seconds per vehicle. Then the motorway reaches 96% capacity.

In the above example the Ramp Signals fail because there is too much traffic. By default the signals will release a vehicle every ten seconds or turn off.
Other factors that contribute to the data that the signals collect (which is not included in the above example) are;

• If there is another on-ramp ahead of the first on-ramp with signals on it then it will take this into account i.e. the first on-ramp signals will take data from the second ramp to determine a capacity level - if the overall capacity goal is 96% then the first ramp will reach this in conjunction with the next ramp by both allowing intervals that can reach that capacity level.
• Ramp Signals can be manually programmed or ones that are isolated may have none of the technology outlined above.
• Esmonde Road ramp-signals will run between 6.30am and 7.15am, then turn off, because traffic demand is too high after that point.

Examples and locations of Ramp Signalling in Auckland

Status: Completed in November 2009

Ramp Signalling will eventually be installed on the whole Auckland Motorway network, with some exceptions. Currently there are seventy ramp signal sites on the Auckland motorway network.

Ramp Signalling has been installed throughout CMJ (Spaghetti Junction); Grafton Gully has priority lanes. 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 and Mahunga Drive. Mahunga Drive was the first on-ramp to have signals installed.

Notable on-ramps without Ramp Signalling include 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, causes significant and problematic congestion behind the on-ramp on Khyber Pass Road.
North Western to Northern Ramp Signals, two lanes. More Images	Wellington Street Ramp Signals, single lane.
Curran Street Ramp Signals, two lanes, slows congestion on the Harbour Bridge.	Wellington Street Ramp Signals in action, single lane.
Dominion Road Ramp Signals for the Westbound on-ramp onto the South Western Motorway. Part of the Mt Roskill extension.	Hillsborough Road Ramp Signals for the Westbound on-ramp onto the South Western Motorway. Part of the Mt Roskill extension.
Waterview eastbound Ramp Signals with priority lanes on the North Western Motorway.	St Marks on-ramp Ramp Signalling. Single lane during construction of the Newmarket Viaduct Replacement project.

Results

With Ramp Signalling now being fully installed Auckland wide effects from Ramp Signalling are starting to prove that the investment was worth it.

So far results include:

• So far we are seeing a 10-30 min reduction in the peak period congestion that usually occurs between Hobson Street on-ramp and Market Road.
• 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
The above images are used to show an example of the way ramp signalling is working, these images do not show statistical averages of flow differences between these sections.

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.

In Sydney Ramp Signalling is only used on three on-ramps, only four on-ramps in Melbourne and along a freeway in Brisbane. 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 1980's. 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 1970's 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. Have a look at how Ramp Signalling works in depth here.

Follow the rules of ramp signalling for the good of everyone on the motorways. And remember the 'Little Wait for a Greater Gain'

Ramp Signalling on Wikipedia | Ramp Signalling in the EU | Ramp Signalling in Minnesota | Ramp Signalling in California

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-ramps are the Wellington Street, North Western to Northern and Esmonde Road (CB) on-ramps. The Wellington Street on-ramp now has less traffic volume as a result of the North Western to Northern connections, but traffic still banks up onto the bridge making the wait to enter the motorway at around 30 seconds to 2 minutes. The Esmonde Road on-ramp can also make no difference as traffic volume is so high that when a user gets a green they cannot move at all because traffic in front of the driver has not moved (have a look at this in the FAQ). This has resulted in the signal not running during extremely busy periods.

Traffic at the Wellington Street on-ramp originally would only bank up on the on-ramp itself but would cause significant congestion on the Northern Motorway. Now traffic banks up onto the bridge. This queue neither grows nor shortens during the peak period but traffic flow on the Northern Motorway has improved.

The North Western to Northern connection 100 metres south of Wellington Street has not helped this either. The connection has reduced traffic volume on the Wellington Street on-ramp but has caused more congestion before the Wellington Street on-ramp meaning that merging is not any easier.

If no Ramp Signalling is in place here traffic would most likely bank up to around the start of Spaghetti Junction. Ramp Signalling is working well here, but is causing significant back logs and waiting times.

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 makes ramp signals worthless. 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.

Once Ramp Signalling is installed on every single on-ramp along the Southern Motorway (in this case) we can expect the Wellington Street and North Western to Northern Ramp Signals to be more efficient. Meaning that the wait time will be less and your journey will be shorter, safer and more predictable.

If you would like to vent your 'ramp signal rage' please do so on the Comment Form below. Once you write in your comment it will be posted on this page and discussed under the criticism header. The New Zealand Herald is running a page on Ramp Signalling here.

Poll | What do you think?
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.

Comment

Comments

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.