M50 - Speed Limit

dulpit

I was in Dublin recently, and it was only the 2nd time I was driving myself on the M50, and I was wondering - why is the speed limit at 100? I would have thought all motorways are at 120??

flazio

The lanes are narrower and the traffic intensity is higher then perhaps any road in Ireland. 100km/h is the safest speed to deal with these factors.

mydiscworld

Too many junctions and idiot drivers. It would be too dangerous tbh.

A national audit of all speed limits has been announced but I'd doubt the M50 would be upgraded to 120.

dulpit

Huh, fairy nuf.

Suppose as it was a Saturday that I was driving on the road, traffic was pretty light, but I'd imagine it must be hectic in rush hour...

niloc1951

dulpit wrote: »

Huh, fairy nuf.

Suppose as it was a Saturday that I was driving on the road, traffic was pretty light, but I'd imagine it must be hectic in rush hour...

This System could be used with for example 90KPH during busy times or when weather conditions are bad and 120KPH when traffic is light and weather conditions are good.

Please Kill Me

I heard it was to keep noise levels down, as the residents in the surrounding estates were complaining??

munchkin_utd

niloc1951 wrote: »

This System could be used with for example 90KPH during busy times or when weather conditions are bad and 120KPH when traffic is light and weather conditions are good.

they are installing that at the moment on the overhead gantries

brandodub

Narrower lanes and reduced sightlines I think is the official reason.

Mc Love

The question is does anyone do 100km/h on the M50??

Also people dont seem to travel at 100km/h on the three lane part of the N7

L1011

Mc Love wrote: »

The question is does anyone do 100km/h on the M50??

Also people dont seem to travel at 100km/h on the three lane part of the N7

I often find that doing an actual 100km/h (GPS not indicated - cars over-read almost across the board) on either road has you going faster than most traffic, when the road is busy

When its not busy, try 130+ for the N7 anyway.

antoobrien

MYOB wrote: »

When its not busy, try 130+ for the N7 anyway.

It's 30km over the speed limit and the traffic corps seem to love that road (don't go out there often but any time i'm on it I see at least one car).

L1011

antoobrien wrote: »

It's 30km over the speed limit and the traffic corps seem to love that road (don't go out there often but any time i'm on it I see at least one car).

Its what the running speed seems to be at quiet periods.

Work on the N7 and its (surreally, as I live on the M4) easily the easiest way home and I haven't seen a single TC car doing checks in five years. Seen a few camera vans at Rathcoole inbound though.

seamus

Reduced sightlines and more bends was the official excuse for the southern section of the M50.

Narrower lanes is the official excuse for the updated M50.

This is of course complete nonsense. The lanes on the M50 are now at the standard Irish width of 3.5m, which doesn't appear to pose an issue for 120km/h speed limits on other new Irish motorways.

It was reduced from the UK standard of 3.75m (12 feet) when the third lane was put in, and somebody decided this was a good reason to reduce the limit to 100km/h.

Clearly nobody informed them that some sections of the German autobahn with no effective speed limit, also have 3.5m lane widths.

L1011

seamus wrote: »

Reduced sightlines and more bends was the official excuse for the southern section of the M50.

Was noise, actually. Its a planning constraint - can't exceed 100 on the existing planning permission

antoobrien

MYOB wrote: »

Was noise, actually. Its a planning constraint - can't exceed 100 on the existing planning permission

i think there was also something about the distance between the junctions not being enough to justify 120km/h as well.

L1011

antoobrien wrote: »

i think there was also something about the distance between the junctions not being enough to justify 120km/h as well.

This is just the southern cross section in question - the distances between the junctions there are huge!

icdg

MYOB wrote: »

This is just the southern cross section in question - the distances between the junctions there are huge!

The speed limit on the Southern Cross was 60mph on the day it opened, so it must have been a planning permission thing.

OP the 120 km/h limit for motorways is just a default, not a requirement. Road authorities are free to set special speed limits on motorways just as on any other road.

L1011

icdg wrote: »

The speed limit on the Southern Cross was 60mph on the day it opened, so it must have been a planning permission thing.

It was - noise concerns as I mentioned.

Brian CivilEng

If you travel the whole length of the M50 you'd take 4mins longer travelling at 100km/h than at 120km/h. Hardly a big issue, but time savings of 4mins have been used to justify spending millions on other schemes.

I worked on the M50, and at the time one of the reasons given for the lower speed limit was higher capacity. Traffic can travel closer together at 100 than at 120, so more vehicles can physically fit on the road. In addition to the narrower lanes, noise and junction spacings I don't think that 100km/h is a bad compromise.

quietriot

It might be 100kph but I can't remember ever having done 100kph on it.