Should we do away with speed limits on our interurban motorways?

marious · 26-09-2009 09:49AM

note that some of tailgating is caused because of drivers occupying fast lane constantly, slowing traffic behind - drivers losing patience sometimes pushing them to pull in by tailgating or I would say some people just hate to be overtaken, have that feeling sometimes? some cars make it hard for you cause they hate to be "swallowed" ;-)

corktina · 26-09-2009 11:00AM

marious wrote: »

to apply higher speed limit (IMAO):

1.get rid of L drivers, they exist on motorways as you know and nobody is doing anything about it(gardai).

2.do something with tractors ?!?! on our motorways

3.RE educate people about using lanes on motorways and INDICATING

4.RE educate people that hard shoulder on motorway isn't parking for answering mobile phone

5.RE educate people of importance of using dipped headlights as some people switching them on only when they don't see the road ?!?!

6.RE educate people that when they joining traffic they MUST give way to people using left lane! and indicate

7.Educate people that when they driving on left lane, want to overtake somebody and see in the mirror car approaching on fast lane with great speed 200m behind them to WAIT till he'll pass them first, not forcing him and probably cars behind him to brake suddenly

8.Educate people that when they using full lights they're dazzling incoming traffic and cars in front of them AS WELL (up to 300-400m), and to switch fog lights off

thank you

No6..you need to add that the people in the left lane should accomodate people joining by moving over if possible or adjusting their speed AND the people joining should be accelerating to match the speed of the left lane in order to merge safely.

Zoney · 26-09-2009 11:53AM

marious wrote: »

note that some of tailgating is caused because of drivers occupying fast lane constantly, slowing traffic behind - drivers losing patience sometimes pushing them to pull in by tailgating or I would say some people just hate to be overtaken, have that feeling sometimes? some cars make it hard for you cause they hate to be "swallowed" ;-)

Those not pulling in from the outside lane may be displaying poor driving and bad manners, however, anyone losing patience and tailgating is displaying gross ignorance of basic physics and is a lethal moron and shouldn't be on the roads.

corktina · 26-09-2009 12:05PM

two wrongs dont make right eh Zoney? tis true. We should endeavour to educate moronic drivers BY EXAMPLE.

Zube · 26-09-2009 04:17PM

corktina wrote: »

We should endeavour to educate moronic drivers BY EXAMPLE.

It's interesting how that works: if I pass slow traffic and then pull in, the drivers behind me do the same. If I pass slow traffic and stay out (because I see more slow traffic ahead) drivers behind me do the same.

Sometimes a driver in front of me pulls in after I pull in, but I think that's because he's afraid I'm going to undertake him!

marious · 26-09-2009 04:27PM

yes, people are too lazy to come back to slow lane after overtaking, usual thinking:
"I don't give a ***t about that fellow behind me, he can wait until I'll overtake everybody I want first even that next car is 200-300m in front it doesn't matter. I'm not in a rush why he should be?"

Lennoxschips · 27-09-2009 11:14AM

nobody on the road should be in a rush

marious · 27-09-2009 01:50PM

fantastic ! lets close the motorways so, no need to rush things 2,5 or 7 hrs cork-dublin doesn't matter does it?

manutd · 27-09-2009 07:06PM

As some posters have saided 130 km/h on a motorway is a good speed limit. It sayes entering the motorway, that vehicles under 50cc or may not enter. It should be higher.

Lennoxschips · 27-09-2009 08:54PM

marious wrote: »

fantastic ! lets close the motorways so, no need to rush things 2,5 or 7 hrs cork-dublin doesn't matter does it?

no, let's not close the motorways

cantalach · 28-09-2009 12:08AM

Perhaps looking at how cruising speed affects fuel efficiency might sway a few opinions?

Air resistance is the biggest force acting on a vehicle moving at speed on a flat stretch of road. The instantaneous power required to overcome it is proportional to the cube of the speed. As a result, the cumulative energy required is proportional to the square of the speed. Ignoring other factors therefore, the following represents the approximate increase in fuel burn as you increase your cruising speed from 120 km/h:

130 km/h - 17%
140 km/h - 36%
150 km/h - 56%
160 km/h - 78%

You can do the maths yourself as to how this would increase your fuel bill for a particular journey. For me, doing the imperial ton on a round trip from Cork to Dublin would add well over €30 to the cost (and I wouldn't make the whole round trip on a full tank so I'd have to stop and refuel!).

Note also that the above ignores another important factor that would compound the problem. Remember that the vast majority of Irish vehicles do not have 6- or 7-speed gearboxes so the engine will most likely be operating in a less efficient RPM zone when travelling at higher speeds. Granted, electronic engine management systems dynamically tune some of the engine parameters based on the current RPM and throttle position but there is still a sweet spot and this is not in the upper third of the rev counter.

Geogregor · 28-09-2009 01:24AM

D.L.R. wrote: »

or a combine harvester

Are they really allowed on your motorways???????????

corktina · 28-09-2009 04:02AM

cantalach wrote: »

Perhaps looking at how cruising speed affects fuel efficiency might sway a few opinions?

Air resistance is the biggest force acting on a vehicle moving at speed on a flat stretch of road. The instantaneous power required to overcome it is proportional to the cube of the speed. As a result, the cumulative energy required is proportional to the square of the speed. Ignoring other factors therefore, the following represents the approximate increase in fuel burn as you increase your cruising speed from 120 km/h:

130 km/h - 17%
140 km/h - 36%
150 km/h - 56%
160 km/h - 78%

You can do the maths yourself as to how this would increase your fuel bill for a particular journey. For me, doing the imperial ton on a round trip from Cork to Dublin would add well over €30 to the cost (and I wouldn't make the whole round trip on a full tank so I'd have to stop and refuel!).

Note also that the above ignores another important factor that would compound the problem. Remember that the vast majority of Irish vehicles do not have 6- or 7-speed gearboxes so the engine will most likely be operating in a less efficient RPM zone when travelling at higher speeds. Granted, electronic engine management systems dynamically tune some of the engine parameters based on the current RPM and throttle position but there is still a sweet spot and this is not in the upper third of the rev counter.

6 or 7 speed gearboxes can be a red herring...you can have as many gears as you like, but its the final drive ratio that determines what rpm you will be doing at a given speed.

marious · 28-09-2009 04:12PM

its all true but I would say it is obvious...everybody knows that faster journey means more fuel used but let people spend more if they want, some people can afford 200km/h some people can't. I would focus of Irish drivers skills instead

cantalach · 28-09-2009 04:34PM

corktina wrote: »

6 or 7 speed gearboxes can be a red herring...you can have as many gears as you like, but its the final drive ratio that determines what rpm you will be doing at a given speed.

Yes, the final ratio in top gear is ultimately what counts, and in theory a manufacturer could just use the extra gear to achieve tighter ratios without changing the final drive ratio. In practice though, they tend to do both - tighter ratios and a higher final drive (I was recently in a six speed car for the first time and the very low RPM even at high cruising speed was very noticeable). The converse is that a smaller number of gears almost always translates into a lower final drive ratio.

cantalach · 28-09-2009 05:21PM

marious wrote: »

its all true but I would say it is obvious...everybody knows that faster journey means more fuel used but let people spend more if they want, some people can afford 200km/h some people can't. I would focus of Irish drivers skills instead

Yes, most people are aware that driving faster uses more fuel. The point of my post was to point out just how much more because in my experience most people are unaware of the square rule and assume that a simple linear relationship is at work.

There's more to this than simply whether the individual can afford it. We also have to look at how higher speed limits would affect the country's trade deficit and CO2 emissions.

28-09-2009 05:57PM

Having had to pass a tracter on the M6 near Kilbeggan this morning in the dark, a 120K limit is unfortunately necessary.

You can catch up with one of those very quickly, all you need is someone outside of you and your reaction times be a bit slow and you collect it!

Should we do away with speed limits on our interurban motorways?

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