M4 - Maynooth to Leixlip [planning and design underway]

veryangryman

Its not all private traffic. Pile more direct (stopping at Heuston + OCS only) buses from Kinnegad, Enfield, Kilcock, Maynooth and Celbridge) and you'll justify it. The demand is clearly there.

A near-empty bus lane will be abused. May as well let everyone use it

spacetweek

https://www.boards.ie/discussion/comment/120321366#Comment_120321366

They don't need to be reduced. This emissions targets stuff is starting to turn into dogma.

markpb

https://www.boards.ie/discussion/comment/120323284#Comment_120323284

Scientists have collectively agreed that there is incontrovertible proof of climate change and its negative effects. Politicians, world leaders, trans-national organisations are all on board. International agreements have been signed.

Separately, there is a reasonable amount of evidence that induced demand is real and unavoidable and building more urban roads has the opposite effect to their plan.

But spacetweek on boards.ie knows better and wants more car lanes to be built on the N4.

spacetweek

Nope, not what I said.

Once transport is decarbonised (which is happening quickly) this bit becomes untrue: "car journeys need to be reduced to meet our emissions targets."

You can have increasing car journeys and falling emissions at the same time. Maynooth and Leixlip are getting the DART soon which covers the public transport part. Buses are only a distant second to rail when it comes to public transport. Both towns are growing quickly as they should since we have a housing crisis.

It's hard to make a case for how bad this project is. It has gone from 6 laning, to 3+2 lanes + 1 bus lane, to just 1 bus lane. It's basically just paint now.

marno21

https://www.boards.ie/discussion/comment/120323580#Comment_120323580

The chat was in reference to building an additional lane westbound/outbound. Such a lane would allow traffic to get out of the city area faster in the evenings, would mean less idling and unnecessary braking, and would also allow a more free flowing M4 to take additional traffic that is avoiding the M4 because it is so busy. This would free up local roads, and traffic that is going through town centres and urban areas in an attempt to avoid the M4.

Also, if you genuinely think that not widening the M4 will genuinely make any difference to climate change and its negative effects, then I have a bridge to sell you. Induced demand is real and part of the reason why transport infrastructure is being built. DART+ will induce demand also. It's one of the necessities to us having a high quality of life such as we do in Ireland.

Also, as what spacetweek said about decarbonisation.

As things stand, high quality of life and high energy use are correlated, much as people like to disagree with this theory. As things stand, in general, high energy use = high emissions (with exceptions). There are no countries with a high standard of living and low emissions. The objective should be to reduce emissions from energy use where possible, to the point where we fully decarbonise the energy system. The prevailing objective of modern environmentalism seems to be to reduce energy use and reduce peoples quality of life. This will just lead to cynicism and fights against environmentalism, rather than trying to bring people on board with genuine efforts to make progress in this field.

Also, it's important to consider macro vs micro effects of decisions such as not to upgrade the M4. The macro (effect on global emissions totals) effect of this will be absolutely minuscule, but the micro effects of not building this (congestion in the area etc) will be huge. It'll be people in the micro that'll be voting in the next election, and if this keeps happening it'll end up with people voting for candidates who will rail against this approach to Government (Vote for me and I'll stand up for Kildare etc).

lintdrummer

https://www.boards.ie/discussion/comment/120323580#Comment_120323580

Where are all the extra cars going to come from if they made it a 6 lane road? Is your thinking that more people would commute to Dublin from towns further west or is it that more people would buy/use a car if the road was wider? I don't think either of those scenarios are likely, but maybe I'm missing something obvious?

markpb

https://www.boards.ie/discussion/comment/120333015#Comment_120333015

Overall trips in the area will grow if extra capacity is added. People who are currently using the bus/train will see the road as more attractive and switch. People who are currently ruling out jobs that require commuting on that corridor will switch because it’s more attractive. More non-commuting trips will take place as the additional capacity makes the road more attractive and because of the people who switched from public transport to driving - now those people own a car, the marginal cost of an extra trip is tiny and the appeal of driving will keep them using the car. Within a few years, road demand will be at or above capacity once again.

There’s nothing special about the M4 - every city in the world that has added urban road capacity has seen an increase in road demand to match.

lintdrummer

Historically that may be true, but is it correlated to the general growth of car usage more broadly as years went by? When is the data from? And where?

Personally I don't see it being more attractive to people who currently commute on public transport. Traffic is an unknown quantity regardless of road size and makes commute times vary day by day. You would need to find and pay heftily for parking in the city. Fuel prices are high. All reasons to stick to public transport.

I used to live in Celbridge and commute to work in Dublin Airport. There was no good option for me on public transport. Often I would be on the road to work in the very early AM and commuting home at the beginning of peak outbound traffic. The third lane on the N4 as far as leixlip made a lasting difference to traffic flow, which slowed for the final few kms to Celbridge. I don't recall ever getting stuck in traffic on that 3 lane section. So I believe three full lanes westbound would have made a positive, lasting impact on traffic there.

Better public transport options would be more desirable of course, that bloody rail link to the airport is too long coming. But I honestly don't think adding a third lane for general traffic would lead to a huge rise in traffic on the road, it would just improve the situation for existing users of the road. I'm basing that assessment on my experience with the widened 6 lane N4 who's bottleneck is the narrowing to 2 lanes M4 at leixlip.

I told ya

Don't wish to derail the topic.

My view, FWIW, is that the journey time from Kilmainhan to Maynooth would be faster if the two sets of traffic lights in Palmerstown were removed and replaced with a flyover like the one further out the road. And really wishful thinking would be to eliminate the two sets of traffic lights just past Kilmainham.

Whilst the traffic speed from Leixlip to Maynooth can at times, be crawling/stopped, it's definitely stopped at the lights every evening Monday to Friday.

It all goes back to false economies and poor planning, not facing up to a growing population, increasing prosperity leading to increasing car ownership. The list goes on. Build right, build once.

When the DCs were built from Kilmaihnam on the N4 and from the Ashtown roundabout on the N3, there should have been no traffic lights or roundabouts. There were by and large greenfield projects and should have been designed to 'drain' the traffic out of the city centre quickly and efficiently. Similar problems were constructed on the other main roads out of the city.

brianc89

https://www.boards.ie/discussion/comment/120333378#Comment_120333378

The third lane on the N4 as far as leixlip made a lasting difference to traffic flow, which slowed for the final few kms to Celbridge. I don't recall ever getting stuck in traffic on that 3 lane section. So I believe three full lanes westbound would have made a positive, lasting impact on traffic there.

You just described Induced Demand without realizing it. Every time you add a 3rd lane, traffic flows better for a longer distance until it reduces to 2 lanes further away from the city.

The new 3lane stretch just encourages and enables more people to drive without congestion, until congestion is back where you started.

lintdrummer

https://www.boards.ie/discussion/comment/120337501#Comment_120337501

I'm not sure I buy that. My recollection is that before it was widened, traffic was heavy all along the route by Lucan and including as far out as Celbridge and Maynooth. Widening relieved the congestion, but the two lane section from Leixlip outbound is much the same as it always was. Perhaps there is some induced demand but I wouldn't say it's responsible for the traffic issues, they haven't changed because that section of the road hasn't changed.

spacetweek

Widening the M4 would definitely induce more traffic to use it, but far away from a city this is actually OK for the most part. The increase is modest and is just a result of the strong growth of commuter towns around a fast-growing city.

brianc89

https://www.boards.ie/discussion/comment/120343289#Comment_120343289

I don't think Maynooth is considered far away from the city?

Simple fact is, if you make it easier for cars to commute from Maynooth, Celbridge, Kilcock etc etc, then people will 100% use their cars.

Anyway, we might be on the same page here?... I have no issue adding a third general traffic lane outbound. Inbound, it should remain 2 general traffic lanes.

veryangryman

Those who leave the city will also at some point enter it. Why the hatred for people approaching. Remember that some tolls are one way. The reason being that most do a return journey

brianc89

https://www.boards.ie/discussion/comment/120346524#Comment_120346524

Capacity for outbound is more important than inbound. On a Friday for example when people leave the city and travel to the West and North West. Coming back on a Sunday, this traffic is spread over a larger time.

I have no hatred for daily inbound commuters. But you can be absolutely sure, lots of these already have public transport options but choose to drive, and far more of these could switch to PT, following improvements.

veryangryman

But doesn't the same principle of "should use pt" apply to them leaving the city?

markpb

https://www.boards.ie/discussion/comment/120347985#Comment_120347985

I guess they mean that we should undertake a hugely expensive road widening project to benefit people leaving the city on a Friday evening. Send perfectly reasonable 😆

On the other hand, if you widen the road inbound you make it possible for more people to reach the M50 and we all know how efficient and free-flowing that road is in the mornings!

brianc89

https://www.boards.ie/discussion/comment/120347985#Comment_120347985

https://www.boards.ie/discussion/comment/120348400#Comment_120348400

Have you tried getting to a rural part of Ireland with public transport? Believe me I have tried. It's not possible for many people.

I'm not suggesting spending millions widening a road to accommodate Friday evening travellers only, but it's one of the reasons they are prioritising outbound over inbound.

KrisW1001

Friday evening travellers are not the cause of the congestion, they are only the straw that breaks the camel’s back. If the road wasn’t so close to being overloaded with normal evening commute volumes, the relatively small number of weekend travellers wouldn’t cause an issue.

Having asymmetric capacity on a radial route makes very little sense, and I can’t think of any other example of it.

markpb

https://www.boards.ie/discussion/comment/120348519#Comment_120348519

I have actually, for many years. Where in my post did I suggest that people should take public transport though?

brianc89

https://www.boards.ie/discussion/comment/120348653#Comment_120348653

I was referring to the other commenter's post. Some parts of rural Ireland can be reached easily through public transport, but large parts can't.

spacetweek

https://www.boards.ie/discussion/comment/120347985#Comment_120347985

I think that if they are successfully convinced to use PT to get into the city, they kinda have to use it also to get home, having not brought their car!

veryangryman

So the lanes should be equal both sides? Preferably 6 each but ill settle for 3. Sincerely, Captain Planet

farmingquestion

Induced demand this, induced demand that.

People aren't going to be "induced" out of a good commute into one where they're stuck in traffic for hours every day. If people are getting out of public transport and into cars because there's a new lane added, then it's because that commute is more bearable for them.

How about "inducing" some demand for top quality public transport??

Was heading into town the other week and it pissing rain, seen two lads at a bus stop getting soaked with their hands out. Looked in the mirror and the bus went by them. I just couldn't imagine living that life, relying on buses.

veryangryman

Yeah bussing it in the p1ssing rain with poor punctuality of service is no craic

Youd feel sorry for the plebs. When the congestion charge comes in, only the Beamer and Audi sorts will use the roads there. Aint no CEOs getting on a Bus Connects.

brianc89

https://www.boards.ie/discussion/comment/120358244#Comment_120358244

Might be wrong but, respectfully, I don't think you understand the concept of Induced Demand.

It's a medium term well-observed and documented phenomenon, when you widen roads to relieve congestion, people can now justify living further away, cause journey times are lower. Before long, congestion increases and suddenly you're commuting as long as ever.

spacetweek

It's just a pity it's like pulling teeth trying to get better public transport in Ireland. I can see why.

Public transport requires a service to run which means equipment, drivers, mechanics, unions, and the Irish lack of punctuality.

Car transport requires you to get a car and drive yourself there. If you're late, you're on the hook as you were the driver. Not saying it's right, just saying.

This pattern suits a country like this better until we change as a society to one that considers high quality public services to be a right not a privilege.

Charles Babbage

It seems to me that the public investment required is not bus lanes on motorways, but a large park and ride at Enfield and frequent fast trains that drop you in Connolly. Then people can collect themselves by driving or taking a bus there. Also increase the toll at peak commutting times and reduce it at other times to encourage use of the above.

veryangryman

Tracks to connolly are fairly packed as it is so that idea wouldn't hold much water. Weren't those trains dangerously overcrowded a few years back

Charles Babbage

https://www.boards.ie/discussion/comment/120364343#Comment_120364343

Are the tracks packed? I'll bet that there are places in the world where more people are moved on the same amount of track, and the problem is signalling etc. This would require investment, of course.