Widening Motorways

veryangryman

A few posts with the thinking to widen existing lines (e.g M4 to Maynooth/Kilcock and N7 to the M9 turnoff).

Seeing the M50 and a few others where this has been done, does one not worry that in a 3 lane situation, most cars will move to the 2 rightmost lanes instead of staying left.

The 3-lane thing works well in the UK where (in my experience) it is endless lines of trucks who take the left lane, slower drivers in middle and faster/overtaking drivers on the rightmost lane(s). We don't get enough truck traffic to get the same benefits here.

Yes some of it is down to poor drivers/lane discipline also, but even when that generation die out, we'll still be low on the trucks count.

Overall I think the proposed benefit of these is not as high as some say, especially if (as with M50) the lanes get narrower and speed limit is reduced.

Carawaystick

On the other hand you have the M1, which used to have jams in the rush hours, now doesn't.

Lane discipline is pretty poor still especially at off peak times SB where most cars coming on at Lissenhall just move right to the centre lane, whether there is another vehicle in the left lane or not

I'm not so sure about the case for the M4, is there the volume to need it widened? The vms show a 11/12 min journey time from the m50 at evening rush hour to the Maynooth junction

The N7 has traffic backing up along it from the m7 start a lot more and definitely needs widening

coylemj

M7 inbound between the M9 and the Naas North exit (the two lane section) is a nightmare on Sunday evenings, especially in the summer. All it takes is one or two vintage cars coming home from a rally down the country and there's a massive tailback caused by a bottleneck in the outer lane as trucks and everyone else overtakes them, one extra lane will make a huge difference.

L1011

The N7 and N4 would be impassable if still two lane.

Banjoxed

The M8 seems relatively narrow in the overtaking lane after Mountrath.

Did they do a cut price spec for the later builds then?

L1011

Yes. Narrower lanes and median, allowing for less land take and smaller structures

Banjoxed

MYOB wrote: »

Yes. Narrower lanes and median, allowing for less land take and smaller structures

I'd rather not drive the M8 after Mountrath. Went to Cashel recently and found it tiring driving with the restricted width and poor lines of sight near Urlingford.

veryangryman

MYOB wrote: »

The N7 and N4 would be impassable if still two lane.

I agree with that but I also think that it will take a long time before the 3 lanes are utilised properly (driver mentality etc) in these sections

L1011

Banjoxed wrote: »

I'd rather not drive the M8 after Mountrath. Went to Cashel recently and found it tiring driving with the restricted width and poor lines of sight near Urlingford.

Still a huge improvement in sight lines, road capacity and eliminated cross-over risk than the old N8.

Banjoxed

MYOB wrote: »

Still a huge improvement in sight lines, road capacity and eliminated cross-over risk than the old N8.

Don't fancy bouncing off the central median overtaking a swerver. It's still a bit **** after all the money chucked at it.

Jamie2k9

MYOB wrote: »

Yes. Narrower lanes and median, allowing for less land take and smaller structures

Is it the same on the M6/7/9/11. Just you often hear of a lot more serious accidents on the M8 compared to other motorways.

coylemj

Jamie2k9 wrote: »

Is it the same on the M6/7/9/11. Just you often hear of a lot more serious accidents on the M8 compared to other motorways.

M6 and M9 lanes are as wide as you need, I haven't been down the new M8 so was surprised to see that it involves narrower lanes.

I drive the M4 (Dublin to Kinnegad), M6 (Kinnegad to Athlone), M9 (M7 interchange to Waterford) and M7 (Dublin to Limerick) frequently and have never noticed that one is different to the other so I assume the M8 is the only one that involves lanes narrower than the others.

L1011

It doesn't have narrower lanes. Same width.

The concrete barrier is designed to deflect low angle impacts back on track, hence the step on it. Hitting a wire or Armco barrier at any angle is a guaranteed damage to both car and barrier.