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Debunking the Induced demand argument

veryangryman · 2022-12-16T10:07:57+00:00

Keeping this short. 2 points: * If you build a Motorway from Ballina to Belmullet, it will not get clogged up. * Those who whinge about it happening in Dublin forget that Dublin was a pretty overpopulated place even before the M50 was built. Alas we didn't start with 4 lane Motorways. We did so with crappy 2-lane dual…

veryangryman

Keeping this short. 2 points:

If you build a Motorway from Ballina to Belmullet, it will not get clogged up.
Those who whinge about it happening in Dublin forget that Dublin was a pretty overpopulated place even before the M50 was built. Alas we didn't start with 4 lane Motorways. We did so with crappy 2-lane dual carriageways with non freeflow junctions.

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KrisW1001

You might as well try to debunk gravity.

Your first point: your new motorway won't get clogged because you grossly overprovisioned, but I guarantee you that if you counted the traffic along the corridor before it opened, and then again a couple of years later, you'd find it massively increased from a small base. Where did those extra trips come from?

Induced demand exists. Every time you improve a link, it brings in people who would not have used it previously; it also encourages people to use the link more often. This is sometimes the desired outcome - road improvements to tourist areas and retail zones are done for this exact reason.

If you widen a commuter road, people living further away will consider commuting into that city because capacity has increased, and the wages are usually higher in city locations. Other commuters may be tempted to switch from using the bus, to instead using a car. Cyclists may choose to switch to a car now that traffic has "improved". But that means that before long the road is back to its earlier, congested, level of traffic.

You are free to deny this, but just be aware that you're not denying some "green ideology", Induced Demand is an observed fact of traffic planning that's been seen everywhere on Earth for over half a century. When the huge commuter road networks were built out in the USA in the 1950s and 1960s, induced demand was factored into the projections, but the planners back then didn't realise that it's not a once-off spike in demand, but a continuous growth in traffic.

It has happened in Dublin. The M50 freeflow scheme caused traffic numbers to increase on the mainline, as drivers switched to cars. The new road induced demand for road travel. Same thing happened after N7 was widened, same after Newlands Cross. Every time you make a road easier to use, it gets more users until it clogs up again. That's the phenomenon you're trying to say does not exist.

hans aus dtschl

If induced demand didn't exist then building roads for the betterment of local economic areas would largely be a wasted effort. If your proposed new road didn't move more goods and people than before then it wouldn't actually be economically viable to build it at all in the first place. If we build that proposed road ONLY with safety or convenience justifications in mind, then we could achieve similar effects through safety upgrades (barriers, surface, etc) and policing.

Part of the justification of building those newer roads is to try to stimulate growth and move more people, goods and services than before. If the growth would have happened anyway without the road, and the road construction is purely to "facilitate" growth that was "happening anyway" then you would see similar growth rates in areas without congestion as compared against areas with these big fancy new roads.

The N17 wasn't particularly congested when I drove on it prior to the upgrade. People in the North West weren't crying out for it to be upgraded for convenience or safety sake: they hoped that it would induce economic growth (and associated traffic is a by-product).

hans aus dtschl

I understand why people might want to debunk "induced demand" but bear in mind that it's not a bad thing in and of itself. Often you actually want to use the road building to stimulate the growth. It's actually one good way that a government can influence economic growth.

Induced demand is only really "bad" when it's lopsided and skewed towards one unsustainable mode. That is to say when you don't invest in sustainable modes at all and only really invest in roads. Unfortunately that's been us for the last few decades. Likely because roads are great "bigger CapEx/smaller OpEx projects" as compared with, say, rail. Also likely because of our very dispersed historical settlement patterns.

So the counter-argument to people highlighting "induced demand" shouldn't really be "that's a myth", rather it should be "we're investing heavily in the sustainable modes on the same corridor, and the induced demand isn't a bad thing". The catch is that you need to keep measuring your sustainable mode shares and trying to improve them, and local authorities are loathe to be bound by this (because it's quite difficult to improve mode shares, because cars are a sunk cost).

veryangryman

Why not invest in alot of buses and direct routes from commuters to use these currently "unsustainable" roads.

Every town upto say 60km out can have a direct (no stops) service to Heuston and OCS that on average gets you to OCS for 8.30am. There is surely the demand for that sort of service.

TnxM17

https://www.boards.ie/discussion/comment/120003702#Comment_120003702

There is a need for this service, but not a demand and it will remain that way as long as there is no large financial burden to continue to commute alone in a private car.

While a 'no stops' service would be excellent for many commuters they will still get snarled up in traffic. Until a service is reliable and much faster and people will still prefer to use their cars and enjoy their own private space.

cantalach

Just make city bus services free is my view. Dublin Bus total fare revenues for 2019 (last “normal” year) were just €262M. That’s small change for the State compared to the economic benefit it would bring. I don’t think Bus Éireann break out their revenue so it’s hard to see the cost of the city bus services in Cork, Limerick, Galway, and Waherford. But it can’t be more than the Dublin Bus figure. Even if they just tried it for a month to see what would happen.

brianc89

https://www.boards.ie/discussion/2058276006/debunking-the-induced-demand-argument

Are you trolling or trying to make a serious point?

Induced Demand is a known and accepted phenomenon, related specifically to cars. It is not up for debate.

The more roads you build, the more people will drive on those roads. This leads to congestion. If you build another road to relieve that congestion, it just fills up again. A never ending loop.

The M50 for example is a much needed piece of infrastructure. However, if we were to build another "M50" loop 20km further out to relieve congestion, it would absolutely induce demand into cars.

brianc89

https://www.boards.ie/discussion/comment/120006994#Comment_120006994

I think we need to clarify 2 distinct points here:

• the theory of "Induced Demand" is related to building new roads to relieve congestion on existing roads. Example is widening roads into a city to add additional car lanes.

• new road infrastructure which didn't previously exist, and which stimulates economic growth is not "Induced Demand"

There's a difference between stimulating economic growth and the never ending widening of existing roads to "relieve" congestion (think USA).

Flinty997

I assume you've seen this...

https://www.youtube.com/watch?v=pCzCJzwrB_c&ab_channel=Zipidi

SeanW

https://www.boards.ie/discussion/comment/120002906#Comment_120002906

It's important to note that the M50 expansions did not occur in a vacuum. At the time, Ireland was growing economically and probably also population wise and there was a shift towards Dublin. Meanwhile other aspects to facilitate this growth were being neglected, things like social housing and public transport received limited investment at best. A few platform extensions and a new signaling system for existing DART and Commuter lines, a couple of tram lines, and sod all else. As someone who had the misfortune of being at the coalface of Dublin's commuter transport systems in the years leading up to the pandemic, I can confirm that it was just all-around terrible with every mode (DARTs, Luas all short-haul Commuter services and many bus routes) being over-used and (in the case of buses) painfully slow. And from what I had heard from others, my experience was far from the worst.

Imagine an alternate history in which the M50 improvements were paired with massive extensions to public transport, such that there were now DARTs running to/from Navan on a 20 min headway, the DART Underground was carrying electric trains full of people from the Kildare line to Stephen's Green and beyond, and a high-floor heavy rail Metro had been built from Swords to Bray, with expansions ongoing to Tallaght, Blanchardstown etc. I suspect that the M50 would not be such a mess at peak times. More specifically, I suspect that people use the M50 not simply because it is available, but because it was all that is available.

veryangryman

Given the very broke nature of the country in 1980s when the M50 was planned, I can't imagine the money was there to also build PT. Even getting an EU loan was a nightmare back then. We had to agree that non stop assrape toll contract to get even the M50 built.

These days with finances more stable we should.be doing more on all fronts. But I certainly won't agree that doing nothing(and rail improvements tend to be glacial) instead of widening roads that clearly need widening. Of the widened roads fill up, great. More overall get through and guess what - they make money while we wait for the glacier railways to get built

hans aus dtschl

This thread is pleasantly conversational I must say. I was expecting a spiral into heated argument...well done all!

Flinty997

https://www.boards.ie/discussion/comment/120012215#Comment_120012215

That's a seems to be a long way of saying you don't believe in induced demand. Despite the overwhelming evidence.

I don't disagree there are issues with public transport. On my own train route as more people used it they made the trains smaller instantly causing overcrowding. Very unpleasant. Partly the reason I didn't renew my annual rail ticket and switched back to the car pre COVID. Post COVID the traffic on the train isn't quite recovered and that's partly why I'm back on the train some of the time.

LucianBelmau

Just a quick question. One of the reasons why rail improvements/works are so slow is the planning permission process which is notoriously slow (and I know the government are trying to reform it atm). If that's the case, aren't motorways etc. subject to the same process? Once the drilling gets going, things do get built quite fast (luas cross city /extensions are a good example of this). Do roads/motorways follow a different procedure?

Charles Babbage

https://www.boards.ie/discussion/comment/120006997#Comment_120006997

No point in this unless there are buses to get on. At present, the bus service cannot even run all of its existing timetable.

However, there needs to be a willingness to run buses which won't always be revenue raising. One example would be express buses on the M50, which should have been there from the day the road opened. A road was opened which greatly improved driving times but no attempt was made to ensure that public transport remained competitive to that. Perhaps there was not the capital to invest in the M50 and a metro or the like but there surely was enough to run a bus.

Flinty997

https://www.boards.ie/discussion/comment/120013674#Comment_120013674

Easier to reroute a road I guess.

Some of these planning permission issues are caused by ignorant people running the projects. They have an habit of choosing the most disruptive and disputed approach and route. It's often caused by poor planning.

They make a dumb short sighted decision earlier that then has knock on effect on future work and projects. They seem to prefer to have arguments than plan things properly.

Flinty997

https://www.boards.ie/discussion/comment/120013806#Comment_120013806

Through my old estate they widen the road chopped trees to great a bus lane. Cost a fortune.

Then artificially bottlenecked it two places to a single lane for no reason.

They also put in a set of lights that were not needed.

KrisW1001

Induced demand is not unique to roads; it also affects rail infrastructure: when capacity and number of services increases on a line, journeys increase more than linearly (e.g., when you double the frequency and you get more than double the journeys). The reason why this induced demand is not a problem for rail but is bad for roads is that rail transport is coordinated to make extremely efficient use the available infrastructure, while private car transport is the least efficient way to use road-space.

SeanW

https://www.boards.ie/discussion/comment/120013664#Comment_120013664

I think the case is somewhat overstated. And in the case of Dublin, it only stands to reason that there would be less peak time private car use if there had been a functional public transport system and/or a decent supply of affordable accommodation.

Flinty997

https://www.boards.ie/discussion/comment/120015114#Comment_120015114

The problems in Ireland existed before the housing crisis. It's about a society and culture that is prioritizing cars over other choices.

SeanW

I disagree. If you look throughout Europe and their cities you will find in many cases that not only did their governments go much further to prioritise people's ability to get around by car than anything we ever did, but they also provided and expanded upon world class public transport systems. This is common in the UK for example where city centre motorway networks are often accompanied by full scale regional metro systems, but also in cities like Amsterdam where presumably significant money was spent on things like the IJ-tunnel and the A10 ring motorway (which fully encircles the city), while they maintained their extensive tram system, while building and continuing to improve their Metro at the same or similar times.

Blaming "society and culture" or "induced demand" for the failure of successive governments to invest appropriately in ALL forms of transport (and the predictable problems that caused) seems to me to be a case that is at best overwrought. And the housing mess certainly isn't helping.

Though, to be fair, we did vote for these clowns so "we the people" must take some responsibility.

Flinty997

Amsterdam isn't prioritizing cars. Its diverting it away from the city. That happened through social pressure.

As for the UK

https://www.migrationwatchuk.org/news/2022/01/11/london-becomes-the-most-congested-city-on-the-planet#:~:text=London%20has%20become%20the%20most,Cheltenham%20(see%20media%20report).

SeanW

London has many of the same problems as Dublin, growing continuously with housing and transport not keeping pace, as your link shows. They are trying, Crossrail has no doubt helped, but they'll need to continue and pick up the pace if the population growth of London is to continue. I had been thinking more of Northern cities in the UK in my previous posts.

CrabRevolution

https://www.boards.ie/discussion/comment/120015834#Comment_120015834

Common for UK cities to have Metros? There's Metros in London, Newcastle and Glasgow, where are the rest?

SeanW

Manchester also has a weird tram-metro hybrid thing and Liverpool has a regional electric railway system. Newcastle-Upon-Tyne is the example I'm most familiar with and they simply do not have the same problems as Dublin has. Nowhere near.

I find it interesting that London has been mentioned in this thread because it as far as I am concerned actually debunks the induced demand argument. The claim - if I understand it correctly - is that if you provide more things for drivers, more people will drive, making traffic congestion ultimately worse - and that this is the only cause of traffic congestion, not for example a lack of housing or public transport, the same being side issues at most. Yet, London not only has not built new roads for decades, but has actively sought to discourage people from driving. They have Congestion Charging, an Ultra Low Emissions Zone and a lot of punitive 20MPH limits citywide. And these rules get more onerous on an ongoing basis. Yet congestion (at least according to the poster above) seems to keep getting worse.

How is it possible that a city that seeks to actively discourage driving (i.e. the opposite of inducing demand) keeps having more and more congestion?

TnxM17

https://www.boards.ie/discussion/comment/120026373#Comment_120026373

"..and that this is the only cause of traffic congestion"

Where does the above quoted claim come from?

TnxM17

https://www.boards.ie/discussion/comment/120028158#Comment_120028158

Obviously I have as it's a direct quote from the paragraph, and I have reread it in its entirety again.

If I've missed something, please share.

magicbastarder

https://www.boards.ie/discussion/comment/120005388#Comment_120005388

doesn't research show that once you reach 'cheap' PT, further price reductions have little effect? improving PT is much more effective than cheapening it further. i would not say 'just' €262m - over a quarter of a billion!

keeping all other things equal, that'd pay for (or cause sacrifice of) quite a few bus routes.

cantalach

https://www.boards.ie/discussion/comment/120028295#Comment_120028295

By any chance was that research done in a city or country where payment and ticket checking is done in a frictionless or low-friction way? The actual process of getting 70+ people onto a double-decker bus when every one of them has to interact with the driver is extremely slow, and that in itself is a huge disincentive to use the bus. Pre-Covid, the 215 bus here in Cork regularly took 15+ mins to board at the stop by the City Gate business park (it may still do but I now WFH). That 15+ mins is very inefficient use of a valuable asset and very wasteful use of the driver’s salary. In Berlin, the system is trust-based and your ticket is in a smartphone app. You just get on the bus. There is no validation or interaction with the driver. If the PT operators can’t get with the year 2022 and embrace a system like this, then they shouldn’t be allowed charge at all. The friction is part of the problem.

By the way, I realise that €262M is a lot of money. But it has to be seen it the context of the potential economic benefit of a massive mode shift to PT and commuters having a bit more money in their pockets for elective spending.

magicbastarder

Will see if I can find a link to what the research was...