Part of the recent 30KPH inner city speed limit to be scrapped.

Iwannahurl

monument wrote: »

Our cars are little different than UK or German cars so, you're talking nonsense. Next thing you're going to claim is that all Germans drive little dinky cars with tiny engines? And drivers adjust.

And as in Germany, 30km/h speed limits are very important in town and cities at night as a solution to noise pollution from cars -- a problem Dublin suffers from acutely.

I'm puzzled at some drivers' objections to this proven road safety measure on the grounds that driving at 30 kph is difficult. In another thread on this topic, one driver claimed that it was "physically painful" and in this thread we have someone with advanced driving qualifications saying it's "ridiculously hard".

Maybe I'm missing something, since I only passed the bog standard driving test and my car just has a rather unexciting 1.6 petrol engine, but I don't find it difficult at all.

When I was in the Netherlands a few years ago, I encountered many 20 kph zones in the area I was based in. Yet the speedo on the car I had the use of (diesel Passat estate if I remember correctly) started at 20 kph, not zero. Since sitting still with the engine running was not a reasonable option I took my chances. I was frequently overtaken by 'speeding' motorists in the 20 kph zones.

Is it just Irish drivers that find 30 kph zones so challenging? Such lower speed zones are common in cities and towns right across Europe. For example, over 80% of the road network in German cities like Stuttgart and Munich has had a 30 kph limit for the last decade or more. Are all those Germans driving their high-spec BMWs, Mercs, Audis and VWs finding the experience "physically painful" and "ridiculously hard"?

gurramok

Victor wrote: »

Driving slow is fuel efficient. It is stop-start traffic (and racing to the next red traffic light) that is fuel inefficient. Driving slower reduce the stop-start effect.

Tell that to the constant red lights at each junction on many routes in the city. You are forced to speed in order to make the next light to avoid the stop start scenario. Its anti-safety.

Anyway, there has been hardly any enforcement of the 30kph zone so changing it now still makes no difference unless you put speed camera vans on every street.

Still this talk of 'safety for pedestrians' will do nothing for those pedestrians killed by trucks and buses every year travelling at less than 30kph on turns.

-Chris-

gurramok wrote: »

Still this talk of 'safety for pedestrians' will do nothing for those pedestrians killed by trucks and buses every year travelling at less than 30kph on turns.

That's an education issue and probably wouldn't be affected by a change in speed limit tbh.

BostonB

monument wrote: »

Not as affective as it should be, but not meaningless. Speeds are down slightly and with more enforcement speeds can be brought down further. At peak time there is not always grid lock everywhere, there's a lot of needless rushing from one set of lights to the other....

I can only speak of my personal experience. I don't see anyone heeding these limits on my daily commute.

BostonB

gurramok wrote: »

Tell that to the constant red lights at each junction on many routes in the city. You are forced to speed in order to make the next light to avoid the stop start scenario. Its anti-safety.

I'd qualify that, by saying its not all junctions. But some are especially bad. And worse again at peak. Driving off peak its less an issue.

gurramok wrote: »

Anyway, there has been hardly any enforcement of the 30kph zone so changing it now still makes no difference unless you put speed camera vans on every street.

Still this talk of 'safety for pedestrians' will do nothing for those pedestrians killed by trucks and buses every year travelling at less than 30kph on turns.

+1

Thats my experience. No enforcement.

When I'm cycling, traffic speed isn't the biggest problem. Being cut up, or people not giving you space, or pulling out across you is. I avoid speeding traffic, by cycling at peak when the cars barely move, and also by avoiding roads where speeding is especially bad.

Iwannahurl

gurramok wrote: »

Tell that to the constant red lights at each junction on many routes in the city. You are forced to speed in order to make the next light to avoid the stop start scenario. Its anti-safety.

Anyway, there has been hardly any enforcement of the 30kph zone so changing it now still makes no difference unless you put speed camera vans on every street.

Still this talk of 'safety for pedestrians' will do nothing for those pedestrians killed by trucks and buses every year travelling at less than 30kph on turns.

Nobody is forcing anyone to speed.

Inappropriate speed can increase traffic congestion. Lowering the average speed of traffic in certain circumstances can actually decrease congestion.

Lower mean traffic speed makes the roads safer on average.

gurramok

Iwannahurl wrote: »

Nobody is forcing anyone to speed.

Inappropriate speed can increase traffic congestion. Lowering the average speed of traffic in certain circumstances can actually decrease congestion.

Lower mean traffic speed makes the roads safer on average.

Try it in rush hour. Most motorists(and bus drivers) know the traffic light sequences off by heart and know that by speeding up to certain junctions they will get to their destinations a bit faster. Its human frustration that takes over at each red light of stop start. Of course if we had green waves, there would be no need for speeding or human irrational emotions taking over.

Iwannahurl

gurramok wrote: »

Try it in rush hour. Most motorists(and bus drivers) know the traffic light sequences off by heart and know that by speeding up to certain junctions they will get to their destinations a bit faster. Its human frustration that takes over at each red light of stop start. Of course if we had green waves, there would be no need for speeding or human irrational emotions taking over.

How much faster, one wonders. It's probably irrational alright, and quite possibly illegal, hence the need for speed controls. Traffic flow is made up of multiple variables, including individual motorist behaviour. Overall, lower speed can decrease congestion, hence slowing down traffic can actually get traffic through pinch points faster.

The problem with a green wave for motorists is that it may well represent a red wave for other road users, such as pedestrians.

SleepDoc

MYOB wrote: »

Driving 7 years, fully qualified, zero points (while driving about 5x the Irish average annual distance), IAM, work as a professional driver. Neither of my cars will run at 30 without serious intervention. They'll roar in first, they'll roar in second, they'll stall in third..

The effect of 30kph on your cars is irrelevant. What is relevant is creating a safe city centre environment for pedestrians, cyclists and a quieter environment for city centre residents.

BostonB

SleepDoc wrote: »

The effect of 30kph on your cars is irrelevant. What is relevant is creating a safe city centre environment for pedestrians, cyclists and a quieter environment for city centre residents.

If cars are irrelevant why not just ban them from the city center.

L1011

SleepDoc wrote: »

The effect of 30kph on your cars is irrelevant. What is relevant is creating a safe city centre environment for pedestrians, cyclists and a quieter environment for city centre residents.

...except that internal combustion powered cars going at 30km/h will generally be louder than cars going at 50km/h

As goes safety, at the times when traffic can move freely I've never seen a single cyclist, or a pedestrian who's safety is impinged by anything other than their own inebriation.

monument

MYOB wrote: »

...except that internal combustion powered cars going at 30km/h will generally be louder than cars going at 50km/h

Maybe in your car, but not overall:



Source: OECD, International Transport Forum report on Speed Management: http://www.internationaltransportforum.org/Pub/pdf/06Speed.pdf

MYOB wrote: »

As goes safety, at the times when traffic can move freely I've never seen a single cyclist, or a pedestrian who's safety is impinged by anything other than their own inebriation.

If you truly have such a high view of other driver's standards I'm beginning to think that you're not on the road as much as you claim to be or you somehow don't see the crazy everyday action of other drivers and all other road users who are not drunk.

SleepDoc

BostonB wrote: »

If cars are irrelevant why not just ban them from the city center.

The effect of low speed on cars is irrelevant.

Paparazzo

I don't think I ever drove down the quays with cars doing 30kph. They always do about 50. Last time I was driving down, I was behind 2 garda vans doing at least 60. I have to let the clutch slip in first gear to go that slow!

ICE HOUSE

The ridiculousness of the whole thing just speaks for itself really.

Iwannahurl

BostonB wrote: »

If cars are irrelevant why not just ban them from the city center.

There is something in what you say.

In 1997 Ghent implemented a mobility plan in the city centre with the aim of addressing the problems of excessive car traffic which dominated the city’s streets and squares. The plan involved the closure of the city centre to all through traffic, as well as a number of traffic management strategies to provide essential access and improved public transport, cycling and walking facilities.

The plan included the following elements:
• The removal of all private car through-traffic by creating a large pedestrian zone (35 ha in total) and traffic-flow measures. Pedestrians, cyclists and public transport are thereby given more space.
• A P-route (parking route) around the city centre ensures optimal accessibility to all destinations and especially to underground parking garages. A parking guidance system makes finding available parking easy.
• Traffic calming has been introduced in the city centre: speed limits in the pedestrianised area have been reduced to 5 km/hour for those with permitted motorised access.

On the third of November 1997, the city centre was closed overnight to through traffic.

L1011

monument wrote: »

If you truly have such a high view of other driver's standards I'm beginning to think that you're not on the road as much as you claim to be or you somehow don't see the crazy everyday action of other drivers and all other road users who are not drunk.

Want a photo of the odo's in my cars then do you?

I have a higher view of driving standards in this country than I do of cycling standards. Having seen two further near collisions today caused by cyclists sailing red lights.

As goes that OECD chart, it shows higher engine noise at 30. Noise from rolling resistance is dependent on road surface and tyres more than speed at speeds that low. Cars doing 30 on modern surfaces with modern tyres are noiser than those doing 50. The OECD is also assuming that the vehicle in question can do 30km/h in second gear easily, which many cars cannot.

L1011

SleepDoc wrote: »

The effect of low speed on cars is irrelevant.

Damage to vehicles is not irrelevant. Low speed driving is damaging to vehicles and causes high emissions.

SleepDoc

MYOB wrote: »

Want a photo of the odo's in my cars then do you?

I have a higher view of driving standards in this country than I do of cycling standards. Having seen two further near collisions today caused by cyclists sailing red lights.

As goes that OECD chart, it shows higher engine noise at 30. Noise from rolling resistance is dependent on road surface and tyres more than speed at speeds that low. Cars doing 30 on modern surfaces with modern tyres are noiser than those doing 50. The OECD is also assuming that the vehicle in question can do 30km/h in second gear easily, which many cars cannot.

Your anecdotal evidence is unconvincing.

If you can't do 30kph in 2nd, do 20kph. The speed limit is not a target.

SleepDoc

MYOB wrote: »

Damage to vehicles is not irrelevant. Low speed driving is damaging to vehicles and causes high emissions.

It's entirely irrelevant in the context of a safe and pleasant city centre.

Iwannahurl

MYOB wrote: »

Damage to vehicles is not irrelevant. Low speed driving is damaging to vehicles and causes high emissions.

Have you any sources for that? I've searched briefly online but I don't really know the terms to use in order to find proper data.

L1011

SleepDoc wrote: »

It's entirely irrelevant in the context of a safe and pleasant city centre.

Firstly, it isn't. If driving in a city is going to damage vehicles, its not a pleasant city.

Secondly, Dublin City Centre is not going to be made safe and pleasant by pointless speed limit reductions. DCC could spend the money they've pissed down the drain on extending and then reducing the limit area, consultations, signage, road painting, etc by maybe providing proper street sweeping, public toilets that don't involve buying something from a private business, footpath repairs, removing the junkies from the boardwalk, I could go on.

Iwannahurl wrote: »

Have you any sources for that? I've searched briefly online but I don't really know the terms to use in order to find proper data.

The live consumption gauges fitted in every car I've seen manufactured post-2004 or so. My personal car consumes about 15l/100km at 30km/h compared to 9 at 50km/h. Its most efficient in fifth (its a six speed surreally) at about 90km/h. Figures are different (and much lower) for my company vehicle but its still much less efficient at 30.

Fuel consumption is directly related to emissions.


^ is old and American, but it shows the general trend. Higher on the graph = lower fuel usage and lower emissions

monument

MYOB wrote: »

Want a photo of the odo's in my cars then do you?

I have a higher view of driving standards in this country than I do of cycling standards. Having seen two further near collisions today caused by cyclists sailing red lights.

I know you drive a lot, and I'm guessing you're a good driver too. My point is there are many, many who are not and you seem to be claiming otherwise.

MYOB wrote: »

As goes that OECD chart, it shows higher engine noise at 30. Noise from rolling resistance is dependent on road surface and tyres more than speed at speeds that low. Cars doing 30 on modern surfaces with modern tyres are noiser than those doing 50. The OECD is also assuming that the vehicle in question can do 30km/h in second gear easily, which many cars cannot.

Not all rolling noise is from the tires meeting the surface and not all of that noise is muted by more modern road surfaces. Your arguments about driving at 30km/h are not an issue or so small of an issue that it does not matter compared to the increased safety -- look at Germany and the UK etc.

L1011

monument wrote: »

Not all rolling noise is from the tires meeting the surface and not all of that noise is muted by more modern road surfaces. Your arguments about driving at 30km/h are not an issue or so small of an issue that it does not matter compared to the increased safety -- look at Germany and the UK etc.

How much noise is contributed by wind resistance at 30km/h, then?

I dispute that there is any increased safety at all. The figures people provide generally refer to areas where traffic is freely flowing, NOT locked inner cities. Comparing apples and oranges doesn't work.

One study I've seen quoted - I'm not going to say for sure it was on here as I can't remember - tried to use figures from the A702 in Scotland, a trunk road running through villages which has 20 limits on it. A comparable situation here would have been, ooh, Castlebellingham pre 2001 - not Dublin City Centre!

monument

On consumption -- on a few of those on the graph, it is best at around 30km/h, it varies a lot. A lot of cars these days are designed for city driving or at least that is factored in. You have to factor in city centre traffic -- the stop and start nature and the people in the environment. You also have to look at the average speed of most of the traffic -- nowhere near 30km/h.

In any case most of the pollution is coming from the sheer volume of cars -- the solution to that is promoting other modes and reducing the amount of cars.

MYOB wrote: »

How much noise is contributed by wind resistance at 30km/h, then?

I don't know, but as I said, modern noise reducing road surfaces only reduce some noise, not all of it. That's presuming that the surfaces are all such and that they are well maintained.

MYOB wrote: »

I dispute that there is any increased safety at all. The figures people provide generally refer to areas where traffic is freely flowing, NOT locked inner cities. Comparing apples and oranges doesn't work.

Nope, most of the figures come from case studies in built up areas -- city centres and residential areas.

Iwannahurl

MYOB wrote: »

Firstly, it isn't. If driving in a city is going to damage vehicles, its not a pleasant city.

Secondly, Dublin City Centre is not going to be made safe and pleasant by pointless speed limit reductions. DCC could spend the money they've pissed down the drain on extending and then reducing the limit area, consultations, signage, road painting, etc by maybe providing proper street sweeping, public toilets that don't involve buying something from a private business, footpath repairs, removing the junkies from the boardwalk, I could go on.

The live consumption gauges fitted in every car I've seen manufactured post-2004 or so. My personal car consumes about 15l/100km at 30km/h compared to 9 at 50km/h. Its most efficient in fifth (its a six speed surreally) at about 90km/h. Figures are different (and much lower) for my company vehicle but its still much less efficient at 30.

Fuel consumption is directly related to emissions.

http://upload.wikimedia.org/wikipedia/commons/a/a9/Fuel_economy_vs_speed_1997.png
^ is old and American, but it shows the general trend. Higher on the graph = lower fuel usage and lower emissions

Lowering the speed limit to 30 kph is anything but pointless. Reason: lower speed is inherently safer.

Contrasting the 30 kph zone with other issues like street sweeping and heroin addicts on the boardwalk is like comparing apples and oranges. The 30 kph zone stands on its own merits, among which increased safety is the most important IMO.

I'll get back to you on the fuel consumption / emissions angle when I find more and better data than the above.

L1011

monument wrote: »

On consumption -- on a few of those on the graph, it is best at around 30km/h, it varies a lot. A lot of cars these days are designed for city driving or at least that is factored in. You have to factor in city centre traffic -- the stop and start nature and the people in the environment. You also have to look at the average speed of most of the traffic -- nowhere near 30km/h.

you're eiter reading the graph backwards - higher is lower consumption, or not realising its in miles. Many cars on it are at their absolute *worst* at 30.

Iwannahurl

MYOB wrote: »

The live consumption gauges fitted in every car I've seen manufactured post-2004 or so. My personal car consumes about 15l/100km at 30km/h compared to 9 at 50km/h. Its most efficient in fifth (its a six speed surreally) at about 90km/h. Figures are different (and much lower) for my company vehicle but its still much less efficient at 30.

Fuel consumption is directly related to emissions.

I haven't got any specific data on emissions yet, but here's a very good primer on fuel saving from those nice people in Volkswagen.

Save as you drive: background information for expert fuel savers.

Their data show higher fuel consumption at lower speeds, but that's because such lower speeds typically occur during urban driving. The graph on page 5, showing test data for a 6-speed Golf 1.4 TSI, gives a figure of 8.2L/100KM for urban driving versus 5.1L/100km for extra-urban driving.

However, the rational and practicable response to such data is not to raise speed limits in urban areas to 120 km/h.

Urban driving is inevitably of the stop-start variety. VW say:

On average, every seventh litre of fuel is consumed in stop-go traffic conditions. »Going with the flow« – which means more coasting and less use of the brake and accelerator – will save you fuel.

A lower speed of 30 km/h improves traffic flow and eases congestion: exactly what Dr VW ordered.

Even better, VW's first fuel-saving tip is: avoid short trips.

A large number of journeys in Dublin City are single-occupant car trips over distances that are eminently suitable for walking, cycling and public transport. 30 kph zones encourage greater use of such travel modes, thereby reducing fuel consumption and emissions overall.

Reducing unnecessary car use would also decrease congestion, which in turn would reduce the level of stop-start driving, which would result in further lowering of fuel consumption overall.

Incidentally, cycling is the most energy-efficient mode of transport: there is nothing on the planet, natural or man-made, that beats it.

Compare that to the internal combustion engine, which according to this US Government source is only 15% energy efficient in practical terms!!! That means every time we drive a car we are wasting 85% of the fossil fuel we use to propel it from A to B. It's a crazy world for sure.

L1011

a lot of text, and nothing to tackle 30 spewing out far more than 50 when the roads are clear

remember, 30 is a dream during the day. You don't get to do it, and as a result the limit is meaningless and has absolutely zero impact on safety.

The issue here is that these limits are 24 hour.

BostonB

All these cars going down the quays or through the 30km/h zone are not parking in it. Most of them of passing through it. Its a transport artery. That point seems to be completely ignored by those reports and stats. That's probably not the case in other cities.

Likewise, the 30km/h is pointless because it isn't enforced. So it makes no difference to noise, safety, or anything else for that reason alone.