# Does your city have ramp meters?



## diablo234 (Aug 18, 2008)

Ramp meters are basically traffic lights that are placed on an on ramp to limit the amount of cars entering a freeway/motorway. They are relatively common in some U.S cities as they are am effective tool in managing traffic congestion.

















A diagram of a typical setup of a Ramp Meter.









Example of a Ramp Meter on I-25 in Denver, CO.









Another example of a Ramp Meter in Portland, OR.

Know of any other cities that have them? And of course as always photos are appreciated.


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## ChrisZwolle (May 7, 2006)

Ramp meters are a widespread phenomenon in the Netherlands, especially in the West.

Not all are efficiently though, I have a friend who lives in Houten (not Houston  ), and when the ramp meters are activated it can take 40 minutes to enter the A27 freeway. hno:


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## earthJoker (Dec 15, 2004)

Yes there are some on the Ring Motorway. Thay are called Tropfenzähler (drop counter):
















http://www.tiefbauamt.zh.ch/internet/bd/tba/de/aktuell/tropfenzaehler.html



> Not all are efficiently though, I have a friend who lives in Houten (not Houston ), and when the ramp meters are activated it can take 40 minutes to enter the A27 freeway.


The thing is, such a system only improves the traffic *on* the motorway, the traffic onto the motorway is slowed down. A tippical "waterbed" situation.


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## bogdymol (Feb 4, 2010)

^^ I remember this ramp meters from my visit in Chicago. First time I saw them I asked a friend from that area why there are traffic lights on the motorway :lol:


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## H123Laci (Dec 6, 2007)

it seems to be not a good idea...

they want to keep the traffic of the freeway flowing, but what about the traffic of the ramps?

it has very limited puffer capacity so it will be backed up to the local roads and streets...

I think its better to let the traffic onto the freeway and let it back up there...

it has enormous puffer capacity...


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## TheCat (Apr 21, 2006)

They are used in Israel on the Ayalon Highway, but the effect is often that traffic backs up far into the main streets and blocks traffic lanes there.


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## x-type (Aug 19, 2005)

frankly - i have never heard of those things!  :shame:


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## diablo234 (Aug 18, 2008)

H123Laci said:


> it seems to be not a good idea...
> 
> they want to keep the traffic of the freeway flowing, but what about the traffic of the ramps?
> 
> ...


Alot of ramp meters actually have sensors at the entrance to the on ramp to detect traffic capacity, so when the traffic on the on ramp affects the intersecting road, the ramp meters automatically turn green to let cars enter the freeway/motorway until the on ramp is not as backed up.


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## kanterberg (Aug 3, 2009)

Here's one from Stockholm. Ramp meters were installed on a few ramps when the congestion charge was implemented in Stockholm in 2004/2005. Because the E4 is excempt from the charge traffic on this road increased when the congestion charging begun.


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## piotr71 (Sep 8, 2009)

I am not sure if we have it in Poland. I presume, such a thing does not exist here. However, I know some places in Europe having that. For instance, A40 in Germany. There is plenty of them on almost every runway/slip road, in most congested and urbanized part of this _autobahn_ 
A picture from autobahn-bilder. Essen:


>


Traffic lights can be found on Britsh motorways as well. I know several slip roads on M25 and M3 with them.


> *Traffic lights could be put on M25 motorway...*


full article back to 2008 to show the reason for that: http://www.telegraph.co.uk/motoring/3397377/Traffic-lights-could-be-put-on-M25-motorway.html
...*and they are* in 2010:








The photo has been taken on M3, but those lights on M25 are very similar to these.


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## aswnl (Jun 6, 2004)

Nearly ALL onramps to the Amsterdam ringroad A10 have a TDI now.
(TDI=ToeritDoseerInstallatie = Onramp Dose Installation = Ramp meter)


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## x-type (Aug 19, 2005)

i think i saw similar thing in Switzerland (or it was Germany?), but on the mainstream motorway, it was very congested and traffic lights have been turning on the red each minute or something like that to break the row


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## ChrisZwolle (May 7, 2006)

Most Alpine tunnels also have ramp meters on the mainline lanes. They call it "blockabfertigung", but the idea is the same.


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## bogdymol (Feb 4, 2010)

Wouldn't it be easier if they would built longer merging lanes instead of ramp meters?


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## Penn's Woods (Apr 8, 2010)

bogdymol said:


> Wouldn't it be easier if they would built longer merging lanes instead of ramp meters?


Probably not cheaper, and not always feasible. At least that's what I assume. (They mostly show up on urban-area expressways that may be decades old when the meters are added.)


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## ChrisZwolle (May 7, 2006)

It has nothing to do with the length of the merging lanes.

A motorway has a certain capacity, for example 2,200 vehicles per lane per hour. If this capacity is approached, this is called saturation. A traffic jam will begin to appear if this capacity is exceeded, for example when there is additional traffic entering the road. 

To lower the influx of vehicles onto the motorway, ramp meters are installed. They can program these to a certain value of vehicles per hour that can enter the motorway. The idea is to ease or avoid congestion on the mainline lanes by limiting the flow entering the motorway.

So it has to do with the amount of traffic, not the length of the merging lanes or on-ramp.

A traffic engineer has to find a compromise between the number of vehicles entering the motorway from the on-ramp, and the queue length on the on-ramp or adjacent streets. If the vehicle flow is too limited, a gridlock will quickly appear. 

Ramp meters are often out of service outside peak hours, to avoid unnecessary stops and acceleration (thus emissions).


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## bogdymol (Feb 4, 2010)

^^Thank you for the answer.

Offtopic: what kind of courses have you followed to be a traffic engineer?


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## ChrisZwolle (May 7, 2006)

You can study traffic engineering at a University of applied sciences, as they are called these days. They call it a Fachhochschule in German. It's not an actual university course in the Netherlands, but comparable to a college education, which you follow after you've graduated high school.

However, although people get in touch with traffic engineering every day you get outside your house, the profession is rather unknown. For example, there are only three colleges in the Netherlands where you can study traffic engineering. (one is in Zwolle  )


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## bogdymol (Feb 4, 2010)

Are you a teacher there? :lol:


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## LMB (May 5, 2008)

I've only seen them in the Ruhr area of Germany, although permanently off. 



earthJoker said:


>


Are there any laws supporting the "1 auto" sign, or are those to be freely ignored?


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## xrtn2 (Jan 12, 2011)

Porto alegre BRAZIL


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## diablo234 (Aug 18, 2008)

^^ Are you sure that is a ramp meter?

That looks like a simple traffic light setup to me.


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## Desertstorm (Aug 13, 2011)

Melbourne does on some of its freeways. They're meant to ease congestion on the freeway itself, but IMO they just create another problem, often the queue of traffic waiting to get on the freeway stretches right back to the start of the ramp and you can be waiting 5-10 minutes and can obstruct the surface street if traffic is particularly bad. Basically an identical design to the U.S. system. Here they only operate when traffic is heavy though, so outside of peak periods they are switched off thank god.





WonderlandPark said:


> What is weird, here in Southern California is a ramp meters are installed on transitions to other freeways/motorways. So you exit a freeway to join another and there is a ramp meter in between.





diablo234 said:


> When I visited Minneapolis a while back I also noticed they had ramp meters at freeway/freeway interchanges. I am not sure if those are effective compared with having ramp meters on interchanges with secondary streets/roads.


that sucks! They haven't done that here, we only have them on freeway to surface street interchanges, and not every freeway has them. 

Are they switched on only in peak hour in other countries like here, or constantly regardless of traffic volume/time of day?


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## diablo234 (Aug 18, 2008)

Desertstorm said:


> that sucks! They haven't done that here, we only have them on freeway to surface street interchanges, and not every freeway has them.
> 
> Are they switched on only in peak hour in other countries like here, or constantly regardless of traffic volume/time of day?


In Minneapolis and most other US cities they are only used during rush hour, otherwise they are turned off or they just have a yellow flashing light which means they can proceed without stopping.


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## ChrisZwolle (May 7, 2006)

Ramp meters only make sense when the motorway is operating over, at or near capacity. Although hourly traffic volumes off-peak are actually not that much lower than during peak hour, they don't require ramp metering. Ramp metering is visible proof a motorway does not function properly. Motorway capacity is only marginally improved with ramp metering, but the lack of columns of vehicles merging at the time improves traffic flow. However, it is known that some ramp meters cause unacceptable delays at on-ramps (15 - 20 minutes or even longer is not unheard of).


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## myosh_tino (Apr 8, 2010)

When the West Valley Freeway (California State Route 85) was built from south San Jose to Cupertino in 1994, it was the first freeway to feature metering lights (that's what we call them) on all on-ramps including freeway-to-freeway ramps. After the freeway was opened, the complaints came pouring in about having to wait to enter highway 85, especially on the northbound US 101 ramp to northbound highway 85 in south San Jose. A local newspaper columnist writes...

Back in 1994 and 1995, I tested the meters on Highway 85, and the result was impressive...

* With all meters off, the 25-mile-plus commute from South San Jose to Mountain View took nearly an hour.

* With the freeway-to-freeway meters off and the meters on city streets turning red to green as fast as possible: 45 minutes. That included no wait on the ramp from 101 to 85 in San Jose.

* When the meters were all turned on and slowed down as Caltrans designed, the entire commute — including a five-minute-plus wait at the 101 to 85 ramp — took 33 minutes.


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## Squiggles (Aug 21, 2007)

Madison has a few ramp meters on the Beltline around the south side. They seem pretty pointless though; if you know how to merge, they seem rather unnecessary.


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## poshbakerloo (Jan 16, 2007)

I know in the UK they use them on a lot of the roundabout interchanges to help with the cross traffic


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## keokiracer (Aug 26, 2011)

In The Nethelands we've got a lot of them, but this one is special: *from highway to highway!*
Exact location (green arrow)



They don't use it anymore since shoulder running was allowed op the A9. Further down the road there used to be another one (A205). It's still there I think, but it's never actually working anymore.

There used to be one here (green arrow again) too, but that one is gone


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## volodaaaa (Apr 9, 2013)

I think, most of the traffic lights on motorways are put in front of tunnel entrances in Europe. The task is easy: to avoid vehicles with running engine stay in tunnel during congestions.


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## Rebasepoiss (Jan 6, 2007)

I recently found this Youtube channel talking about different road-related topics. His latest video is on ramp meters so I thought I'd share it here as well:


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## ChrisZwolle (May 7, 2006)

Ha, I subscribed to that channel as well. Apparently he used to be a news reporter.


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