Purpose of on-ramp lights?

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#1970010 6-Mar-2018 16:09

PhantomNVD:
evnafets:

But i agree with the frustration of these lights letting 1-2 cars onto the motorway every 10-15 seconds meaning the traffic backs up into a 1/2 hour long queue clogging the local roads.

I think that’s the key to ‘fix’ them ... changing the intervals to 3-5 seconds would make all of them work better IMHO.

That *might* be too much if the motorway is borderline congested.

But there are plenty of guys with PhD's for this sort of analysis. Maybe NZTA is hiring the wrong propeller-heads.

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#1970017 6-Mar-2018 16:37

I thought the timing on the ramp signals does change depending on traffic volumes. 3-5 seconds wouldn't even be enough for people to react.

gmball

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#1970029 6-Mar-2018 17:02

Something which I have found beneficial overseas which could have a profound impact here, is traffic lights Red/Orange/Green.

Peoples reaction times often lead to lights changing to red before a sufficient number of vehicles have passed through. Having them change to orange before changing to green could assist with getting people primed and ready to move.

While this is different to the on-ramp lights, I think it would have benefit here and surprised that we haven't followed suit like we have with the on-ramp lights.

The on-ramp lights do seem to work well overseas, but their surrounding road infrastructure is also vastly superior to handle queuing traffic. Los Angeles for example, their side streets and surrounding roads are the width of our motorways, and their motorways are 8 - 12 lanes each side. I suspect someone thought if they have it overseas, we should have it too without giving too much thought to the overall consequences for surrounding streets and single lane roads which have traffic leading onto motorways here.

Our surrounding streets being single lane, lead to queuing motorway traffic blocking the path of other motorists who have no intention of joining the motorway, but are placed in a situation where they literally cannot move until the motorway traffic has cleared.

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#1970067 6-Mar-2018 17:53

gmball: Wanting to better understand the purpose of on-ramp lights. Auckland transport say they are activated based on traffic flow, however clearly this isn’t the case in Auckland as they operate all hours of the day, even when minimal traffic on motorways.

Not sure if it's the same all over, but the nearest on-ramps to me (I'm near the SH1/20 interchange in Manukau) have the lights on only when there is significant traffic. Sometimes they turn it on when there is a big problem much further downstream. In those case you might not see if if you're only traveling up a short distance so it's hard to judge if they've got it right or not.

I remember what it used to be like before they were introduced. I much prefer how it works post-ramp-signals. Yes it does move the congestion to the ramp signals but once you get on it's a much smoother run than it used to be previously. My observation pre- and post- ramp signals is you trade a couple of minute wait at the ramp with a 50-200% more time on the motorway itself.

I've found that for short journeys (e.g. just going to the next off-ramp) ramp signals makes it not worth taking the motorway since it's quicker to just take local roads (vs waiting at the ramp). But for longer journeys the fast trip you get once you get on the motorway "pays" for itself quickly.

YMMV I suppose.

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#1970076 6-Mar-2018 18:15

Absolutely happy to wait a few minutes at on ramp lights, the particular ones I encounter create a traffic bottleneck lasting 3km, and easily add 30 minutes to a journey (30 minutes to travel 3km, as that’s quite literally the length of the on ramp queue).

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#1970130 6-Mar-2018 19:39

https://www.nzta.govt.nz/roads-and-rail/management-and-maintenance/traffic-management/ramp-signalling/

They do their job - but they only work within a certain bandwidth.

And the data clearly shows that average travel times (once you are on the m'way) are reduced with these in use.

However local congestion is clearly negatively impacted - but that's not NZTA's problem.....

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#1970136 6-Mar-2018 19:47

An example for why the on-ramp lights are good - when they aren't on and you get a stack of cars come barging through onto the morotway who are practically bumper to bumper and all want to merge at once in the same spot, meaning traffic already on the motorway has to slam the brakes on to make space (causing jams).

If they would just space out and merge like a zip then not such a problem. But unfortunately we are not all central-minded drones using the same playbook..

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#1970203 6-Mar-2018 21:44

The reason these are often on when the motorway is empty is so the boy racers can do some drag racing :)

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#1970207 6-Mar-2018 21:49

What I'd like to know is why they don't alternate either lane with the correct timing. Enforced drag-stripping is a great way to test your turbo in the morning.... until you reach the person in front who can't match speed and merge like a zip.

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#1970211 6-Mar-2018 22:01

When I get home from work in the evenings I travel on the Ellerslie-Panmure on ramp. People have learnt that in order to turn right at the roundabout, they go in the left lane (this is actually just one wide lane), then cut across the traffic waiting at the roundabout to get onto the motorway. Surprisingly, with a few hand gestures here and there, it seems to work pretty well. But I can also see someone crashing into someone as they turn right, while the person waiting for space on the on ramp moves forward at the same time.

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#1970215 6-Mar-2018 22:06

They're cheating and stealing time from the people in the correct queue. Pricks.

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#1970235 6-Mar-2018 22:51

The ramp metering is a bandaid fix for poor local road planning.

The real problem is people commuting and doing local trips on National Highways. The purpose of a highway is for long-distance travel at speed.

Auckland city has neglected to build proper arterial routes for intracity commuting. Hamilton is a city that has planned well and built proper arterials.

Can you name any arterial routes in the former Auckland city that are access limited and have a speed limit greater than 50km/h ? Hint: (there is one).

Ramp metering is kind of like the national Transport Agency raising its middle finger to the local council ineptitude, saying "fix your own city roading network"

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#1970236 6-Mar-2018 22:54

Nudibranch:

What I'd like to know is why they don't alternate either lane with the correct timing. Enforced drag-stripping is a great way to test your turbo in the morning.... until you reach the person in front who can't match speed and merge like a zip.

This is actually a major problem. I have had so many times where Im accelerating at exactly the same speed as the car next to me, Get to the point where someone has to slow down due to the onramp lane narrowing, we both slow down at the same time (still neck and neck), and eventually someone decides to go in front.

This combined with most of the onramp lanes being way too short, means that merging traffic is often joining the motorway at far below the motorway speedlimit.

The ramp signals would work far better if they left them off until the average speed on the motorway directly past the onramp dropped to around 60Km/Hr. And only then turn on that set to help avoid the motorway from jamming.

But instead they often turn them on due to congestion far ahead on the motorway, Which the ramp signals can't fix. Common example is the northern motorway in the afternoon heading south. The southbound ramp signals get turned on due to congestion building before the harbour bridge. (due to 5 lanes narrowing to 3 lanes over the bridge) Even if the rest of the motorway is clear. Another common example is congestion on the northern heading south in the afternoon, between Greville rd and Constellation Dr. Which is due to lots of traffic trying to exit at Constellation drive. Yet the Constellation drive South onramp lights are almost always on as well. Which removes any incentive for vehicles from the Albany area that want to head further south, to drive through local roads to Constellation drive, and join the motorway there. Instead of adding to the congestion around Greville Rd.

And there is the crazy restriction of the ramp lights on the link from the North Western eastbound, to the Northern North bound. Which is done solely to allow more traffic to enter the motorway at the Wellington St onramp. The NW to Nth link becomes the 3rd lane heading through the Vic Park tunnel, so no merging problems with allowing much more traffic on that link. I think that the Wellington St onramp should be either closed during the afternoon peak, Or a super restrictive timing applied to it's ramp signals. So the ramp signals on the NW to Nth link can be either switched off, or put on a much less restrictive time pattern.

Traffic that normally uses the Wellington st onramp can instead use Fanshawe St Onramp. Fanshawe St can in turn be improved by providing a "free turn" lane going left from Halsey st onto the motorway.

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#1970237 6-Mar-2018 23:04

gmball: Wanting to better understand the purpose of on-ramp lights. Auckland transport say they are activated based on traffic flow, however clearly this isn’t the case in Auckland as they operate all hours of the day, even when minimal traffic on motorways.

I understand the purpose was to assist with the flow of motorway traffic, however in Auckland all this seems to achieve is complete gridlock on all surrounding streets.

I live in Point Chevalier Auckland, due to ramp signals at Western Springs, all surrounding roads from Point Chev, St Lukes and Grey Lynn are gridlocked from 7:30am until 10am each morning. This is regardless of a free flowing North Western motorway.
Improvements to the North Western motorway and water view tunnels have been eliminated due to ramp lights for the ramp past Newton Rd which allows traffic to flow between the North Western motorway and north to SH1.
The lights at this on ramp mean traffic flows back past Western Springs and completely impedes traffic trying to get to the City via Nelson Street, or traffic trying to exit at Newton Rd.

I understand what the ramp lights were designed to achieve but the negatives seem to heavily outweigh the positives.

Keen to hear feedback.

I've stood next to the Greenlane roundabout and watched this.

The on-ramp lights *definitely* ration the flow of cars onto the motorway and help keep the motorway flowing. You can tell when people are ignoring the lights as the ramp downstream than chokes the left-hand lane.....and then people try to move over and choke the next lane...and so on. So the cheaters actually slow themselves down AND everyone else.

As for the side streets.....I was in Brisbane last week and they don't use ramp lights on the M1. Every car can than get on the ramp - bumper - to - bumper, of course - then slam into the side of the rolling traffic (who are tailgating)......and everyone soon grinds to a halt....AND the side streets are then completely blocked anyway. They can't get on the motorway because it's not moving right now....

Seriously.....too many cars is too many cars. You can't sugar-coat that. But ramp lights make it better once you actually reach the motorway. They also reduce accidents because there isn't (shouldn't be if people don't cheat) a river of steal slamming in the left lane.

This is where most drivers show how truly dumb they are. When approaching a busy interchange do they slow down a bit and space out? Or do they bunch up, bumper to bumper, so the oncoming traffic can't get in.....and everyone has to slow down to "don't hit me!" single digits?

Of course, 90% do the latter......every day....day after day....and never think about it or learn. You can really see it when a batch of drivers who KNOW what to do go through......everything flows much better.

It's incredible to see so many people who probably imagine they are "good drivers" prove the exact opposite. Especially tailgaiting. More than anything else this causes congestion and actually brings cars to a halt. If you leave 50m-100m in front of you, you can at least roll slowly and absorb some slowdowns...so at least everyone is moving. For sure there is no way to merge into a stream of cars that are stopped. Tailgating is generally what causes otherwise moving traffic to stop....

This is what ramp lights are trying to stop: tailgating down the ramp. .....and drivers already on the motorway can help by - at least - not tailgating in the left lane.

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#1970288 7-Mar-2018 07:01

Aredwood:

Nudibranch:

What I'd like to know is why they don't alternate either lane with the correct timing. Enforced drag-stripping is a great way to test your turbo in the morning.... until you reach the person in front who can't match speed and merge like a zip.

This is actually a major problem. I have had so many times where Im accelerating at exactly the same speed as the car next to me, Get to the point where someone has to slow down due to the onramp lane narrowing, we both slow down at the same time (still neck and neck), and eventually someone decides to go in front.

This combined with most of the onramp lanes being way too short, means that merging traffic is often joining the motorway at far below the motorway speedlimit.

The ramp signals would work far better if they left them off until the average speed on the motorway directly past the onramp dropped to around 60Km/Hr. And only then turn on that set to help avoid the motorway from jamming.

But instead they often turn them on due to congestion far ahead on the motorway, Which the ramp signals can't fix. Common example is the northern motorway in the afternoon heading south. The southbound ramp signals get turned on due to congestion building before the harbour bridge. (due to 5 lanes narrowing to 3 lanes over the bridge) Even if the rest of the motorway is clear. Another common example is congestion on the northern heading south in the afternoon, between Greville rd and Constellation Dr. Which is due to lots of traffic trying to exit at Constellation drive. Yet the Constellation drive South onramp lights are almost always on as well. Which removes any incentive for vehicles from the Albany area that want to head further south, to drive through local roads to Constellation drive, and join the motorway there. Instead of adding to the congestion around Greville Rd.

And there is the crazy restriction of the ramp lights on the link from the North Western eastbound, to the Northern North bound. Which is done solely to allow more traffic to enter the motorway at the Wellington St onramp. The NW to Nth link becomes the 3rd lane heading through the Vic Park tunnel, so no merging problems with allowing much more traffic on that link. I think that the Wellington St onramp should be either closed during the afternoon peak, Or a super restrictive timing applied to it's ramp signals. So the ramp signals on the NW to Nth link can be either switched off, or put on a much less restrictive time pattern.

Traffic that normally uses the Wellington st onramp can instead use Fanshawe St Onramp. Fanshawe St can in turn be improved by providing a "free turn" lane going left from Halsey st onto the motorway.

East bound North Western to Northern SH1 is what I encounter every morning. As as you rightly point out, that on-ramp becomes its own lane so there is no traffic merging onto the Northern.

I usually meet the on-ramp queue heading north at Western Springs, takes about 30 minutes to travel the 3km distance from there to the Northern motorway. I've followed many drivers who will actually drive into the city to enter at Wellington street which simply moves the bottleneck from a 5 lane motorway to a single lane central city street.

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