Suggestion: Type 2 Motorway!

Irish and Proud

Hi to all,

I've been thinking about the gaps in our motorway network, particularly in the Northwest quadrant of the country. At the same time, the traffic levels would not justify a full D2HQ road for most primary roads in the said region.

My suggestion is a Type 2 Motorway, which would carry one lane in each direction. The specs are as follow:

Verges: 1.5m (same as in UK)
Hard Shoulders: 3.0m
Lanes: 3.5m
Median: 2.0m (with concrete barrier)

Total Pavement: 15.0m
Total Alignment: 18.0m

Interchanges: Full layouts to 100kph spec - no LILOs.

The above type of road would generally have a fixed speed of 100kph for all traffic - slow drivers (like those doing 60 or 70kph should face five figure fines for causing tailbacks etc). In the case of poor weather conditions etc, variable speed signs would have to put in place to lower the fixed speed accordingly. The road should have a comfortable capacity of at least 20k PCUs per day. The 3.0m hard shoulder would allow any stationary vehicle to build speed before re-joining the traffic lane.

So, what are the advantages of a Type 2 motorway.

1) The mainline is cheaper to build than a 2+2;
2) Environmentally friendly by comparison to a 2+2 by...
- a) Taking less land,
- b) Sustaining speeds at 100kph - close to the most fuel efficient speed.
3) Consistent journey speeds are more economically efficient.
4) The 3.0m hard shoulder would render the road far safer than a 2+2 or D2 by;
- a) Providing proper emergency provision (not the case with 2+2s),
- b) Allowing safe accumulation of speed for vehicles rejoining the traffic lane (2.5m is too narrow IMO).
5) My estimation is that the D1M would look more attractive, regarding foreign investment, than a 2+2.

Now, the five routes that would definitely fit the bill would be:

N4 Longford to Sligo (N17 junction);
N5 Longford to Castlebar;
N17 Tuam to Sligo (N4 junction);
N24 Waterford to Limerick;
N25 Waterford to Youghal.

After these would come the:

N15 Sligo to Donegal;
N21 Adare to Abbeyfeale;
N22 Macroom to Tralee.

What do you guys think?

Zoney

I don't see why you would want a "motorway" with one lane each way, when what is likely to be built for these routes is "2+2", i.e. cheap dual carriageway with no hard shoulders and basic junctions (not necessarily *all* at grade).

If motorway is desirable for these outlying parts of the national road network, then they could just minimise the junctions on new-build 2+2, and grade separate the few necessary ones (albeit maybe with LILOs and compact GSJs). Then despite the lack of hard shoulder and merely a wire central barrier, the standards could be relaxed and the routes be classified motorway despite a lack of hard shoulder and presumably poorer curves/sightlines (the speed limit could be kept at 100km/h).

ardmacha

Building a new road and then prohibiting trucks from it would hardly be welcomed by the towns and villages on the old road!

javaboy

Five figure fines for causing tailbacks? :eek: That's a minimum of €10,000 for a traffic offence. I can't see any justification for building major single-lane roads. There would not be a significant enough saving in construction time and footprint over a dual-carriageway imo.

To be honest it seems like more of the short sightedness that typifies our transport infrastructure already.

L1011

I'd advocate vehicle type and access restrictions on grade seperated or mostly seperated WS2 bypasses (such as the Bundoran/Ballyshannon scheme); but can't see the argument for the barriers (removing any overtaking opportunities!) or motorway designation...

corktina

a wind up? tell me its a wind up....

loyatemu

what you're basically advocating is 2+2 except with one of the lanes as a hard shoulder instead of a driving lane:

Irish and Proud wrote: »

1) The mainline is cheaper to build than a 2+2;

i'd say it'd be the same

2) Environmentally friendly by comparison to a 2+2 by...
- a) Taking less land,
- b) Sustaining speeds at 100kph - close to the most fuel efficient speed.

again - I'd say the land take and design speeds would be exactly the same as on 2+2

3) Consistent journey speeds are more economically efficient.
4) The 3.0m hard shoulder would render the road far safer than a 2+2 or D2 by;
- a) Providing proper emergency provision (not the case with 2+2s),
- b) Allowing safe accumulation of speed for vehicles rejoining the traffic lane (2.5m is too narrow IMO).

it sounds like W2S with a barrier down the middle, and I personally find W2S terrifying to drive on.

5) My estimation is that the D1M would look more attractive, regarding foreign investment, than a 2+2.

If its a road-type that no-one else has, then I don't see how foreign investors would have much of an opinion on it...

serfboard

Irish and Proud wrote: »

The above type of road would generally have a fixed speed of 100kph for all traffic - slow drivers (like those doing 60 or 70kph should face five figure fines for causing tailbacks etc).

Assuming that it is policed and enforced 24/7 or at least 12/7. Which we know it wouldn't, couldn't or shouldn't be.

BluntGuy

Well, I'm not sure if I'd agree with the proposal.

IMO, if you're building a greenfield 2+2 (which is essentially what the suggestion is, except for the fact that one lane is hard shoulder), you may as well shove in the hard shoulders and make it a low-grade DC, since land-take is pretty much going to be the same. I could accept LILOs and at-grade junctions, but the lack of hard-shoulder is quite annoying...

I only agree with 2+2 when they're retrofitted or very small schemes. The 50 km Longford-Mullingar doesn't sit well with me. I'd prefer low-grade DC...

One proposal I'd like to see used more would be partially grade-seperated S2 or WS2 (like parts of the N52 Tullimore bypass), delivering some benefits of DCs and motorways while not going to the full-expense.