Can public transport investment really fix traffic congestion?

Well, this is fine: traffic in the north west Chinese city of Xi'an on a smoggy day. Image: Getty.

Now and then, someone mentions that a particular transit project did not reduce traffic congestion, as though that were evidence of failure.

In fact, the relationship between transit and congestion is an indirect one. In most cases, it’s unwise to claim congestion reduction as a likely result of your proposed transit project. (In this post “congestion” means that volume/capacity ratio for motor vehicles on a roadway is high enough to substantially reduce average speeds.)

Road widening, however, is also not a very good way to relieve congestion, except in the short term. In his 1992 book Stuck in Traffic Anthony Downs described the effect of widening an expressway in terms of a “triple convergence”:

In response, three types of convergence occur on the improved expressway:

(1) many drivers who formerly used alternative routes during peak hours switch to the improved expressway (spatial convergence);

(2) many drivers who formerly travelled just before or after the peak hours start travelling during those hours (time convergence); and

(3) some commuters who used to take public transportation during peak hours now switch to driving, since it has become faster (modal convergence).

Downs is describing only the immediate effect of the road expansion. Further increases in traffic will come from any new development that is attracted to the road’s catchment as a direct consequence of its expansion.

Prof. David Levinson’s work in the Minneapolis / St. Paul region suggests that, while added capacity generates new vehicle trips, the effect is often not great enough to restore the previous level of congestion. However, your results will obviously vary based on the amount of development that occurs as a result of the new or expanded road. If this development adds enough new vehicle trips to fill the new capacity, traffic congestion can return to near previous levels.

So the only way to make the congestion benefit of new road capacity permanent is to severely restrict development in the catchment area of the road – an impossible bar in most cases. In fact, parties who will profit from further development in a corridor may be part of the political consensus in support of a road expansion, even as the same expansion is marketed to existing residents as a congestion reducing project.

Otherwise, there appear to be two broadly applicable ways to relieve congestion in a substantial and permanent way.

Economic collapse. Traffic congestion drops during economic slowdowns, because fewer people have jobs to commute to, or money to spend on discretionary travel. A complete economic collapse, which causes people to move away from a city in droves, is always a lasting fix for congestion problems.

Correct pricing of road space. Fundamentally, congestion is the result of underpricing. If you give away 500 free concert tickets to the first 500 people in line, you’ll get 500 people standing in line, some of them overnight. These people are paying time to save money.

Current, prevailing road pricing policy requires all motorists to act like these frugal concertgoers. Motorists are required to pay for road use in time, rather than in money, even though some would rather do the opposite – and our cities would be safer and more efficient if they could. Current road pricing policy requires motorists to save money, a renewable resource, by expending time, the least renewable resource of all.

So if transit isn’t a cause of reduced congestion, what is its role? Do transit advocates offer nothing in response to congestion problems that have many voters upset?

In fact, transit’s role is essential, but its effect is indirect.


1) Transit raises the level of economic activity and prosperity at a fixed level of congestion.

Congestion appears to reach equilibrium at a level that is maddeningly high but that can’t be called “total gridlock.” At that level, people just stop trying to travel. If your city is car-dependent, that limit becomes the cap on the economic activity – and thus the prosperity – of your city. To the extent that your city is dependent on transit, supported by walking and cycling, economic activity and prosperity can continue to grow while congestion remains constant.

To quite a comment left on my website, on an earlier version of this post: “Toronto achieved significant downtown employment growth without increasing road capacity after the 1960s, thanks first to increased subway ridership and later due to increased commuter rail ridership. Congestion is still bad on the roads and expressways into downtown, even with transit expansion, but the expansion of transit has permitted the downtown to grow beyond what the road network would have supported.” A similar pattern can be observed in many similar cities.

2) Transit enables people who can’t drive to participate in economic life.

Groups who don’t have the option to drive include many seniors and disabled persons, some youth, and a segment of the poor. Providing mobility to these groups is not merely a social service; it also expands participation in the economy.

For example, during the US welfare reform debate in 1994-96, government began raising pressure on welfare recipients to seek and accept any employment opportunity. For the very poor living in car-dependent cities, the lack of commuting options became a profound barrier to these job placements.

This is really an element of the previous point, since all employment, even of the poor, contributes to prosperity. But this has independent force for government because unemployed people consume more government services than employed people do. This benefit of transit should routinely be described in terms of economic efficiency, as I’ve done here, rather than appealing to pity or to alleged “economic rights,” as social-service language often implicitly does. The appeal of the social service argument is just too narrow, especially in the US.

Hey, at least the train is moving: just another rush hour in Manila. Image: Getty.

3) Transit-dependent cities are generally more sustainable than car-dependent cities.

They cover less land and tend to have fewer emissions both per capita and per distance travelled. The walking that they require is also better for public health, which produces further indirect economic benefits in reduced healthcare costs.

4) Intense transit service is essential for congestion pricing.

Congestion pricing appears to be the only effective and durable tool for ensuring free-flowing roads while maintaining or growing prosperity. Congestion pricing always causes mode shift toward public transit, so quality public transit, with surplus capacity, must be there for a pricing plan to be credible.


5) Surface exclusive transit lanes (for buses, rail, and arguably two-wheelers and taxis) improve the performance of emergency services.

This argument should be much more prominent, because even the most ardent car-lover will understand it. Few things are more distressing than to see an emergency vehicle stuck in traffic, sirens blaring. When confronted with this, all motorists do their best to help. But if the entire width of a street or highway is reserved for cars (moving or parked), and is therefore capable of being congested, it can be impossible to get out of the way of an emergency vehicle even if every motorist present has the best of intentions.

Emergency response should be one of the strongest and most obvious cases for surface transit lanes. Motorists understand the need to drop to a low speed in school zones, to protect the life of every single child. Why do we not accept come degree of delay to save a child who may be dying somewhere else, because the ambulance is stuck in traffic?

In the end, of course, “congestion” is not a good measure of the outcomes of transit. In fact, the very notion of congestion presumes a motorist’s view of the world. I agree with another commenter, Rodrigo Quijada, when he writes:

What we’d like to do in a city is to reduce TRAVEL TIMES. Reducing congestion is a way to do that, but in no way the only one. Over the decades, in places where car transportation has become dominant, people have got used to see travel times and congestion as the same thing, thus orienting their thinking and their solutions to reduce congestion. But this is essentially a confusion.

Still, in real-world transit politics, selling transit projects to current motorists is a necessity, and the current motorist is likely to see her problem as one of congestion. So it’s important to be clear on what transit can readily do for her.

  1. It can provide an alternative to driving which may be faster, more cost effective, and less stressful. This argument can be put quite selfishly: Good transit won’t eliminate congestion in your city, but it can eliminate it from your daily life.
     
  2. Transit helps reduce government spending on social services by enabling transit disadvantaged groups to participate in the economy. This obviously has a range of health and wellness benefit apart from its economic role.
     
  3. It can increase the level of prosperity at a fixed level of congestion.
  1. Its exclusive lanes protect emergency vehicles from congestion-related delays, potentially saving lives.

Jarrett Walker is an international consultant in public transit network design and policy, based in Portland, Oregon. He is also the author of “Human Transit: How clearer thinking about public transit can enrich our communities and our lives".

This article was originally written for his blog, and is reposted here with permission.

 
 
 
 

Here are eight thoughts on TfL’s proposed cuts to London’s bus network

A number 12 bus crosses Westminster Bridge. Image: Getty.

In 2016, the urbanism blog City Observatory had a modest proposal for how American cities could sort out their transport systems: “Londonize”.

Its theory, the name of which referenced another popular urbanism blog, Copenhagenize, was that the key plank of Transport for London’s success was something that even transport nerds did not consider very sexy: its buses.

Though the Tube might get more glamorous press, London’s bus service really is impressively massive: It carries roughly 2.3bn passengers per year—much more than the Tube (1.3bn), close to the New York City subway (2.8bn), and nearly half as much as every bus service in America combined (5.1bn), while serving a population roughly 1/35 as large.

How has TfL done this? By making its bus network high frequency, reliable, relatively easy to understand and comprehensive. We rarely talk about this, because the tube map is far more fun – but the reason it’s so difficult to fall off the transport network in Greater London is because you’re never that far from a bus.

Given all that, we should probably talk about TfL’s plans to rethink – and in most cases, cut – as many as 36 different central London bus services over the next few months.

I’m not going to rehash details of the changes on which TfL is consulting from next month: there are just too many of them, and anyway it’s someone else’s scoop. The story was originally broken by Darryl Chamberlain over on 853 London; there’s also some fascinating analysis on Diamond Geezer’s blog. You should read both of those stories, though preferably not before you’ve finished reading this one.

Before offering my own analysis of the proposed changes, though, I should offer a few examples. More than a dozen routes are facing a trim: the 59 from King’s Cross back to Euston, the 113 from Oxford Circle to Marble Arch, the 171 from Holborn all the way down to Elephant & Castle and so on. A couple – the 10, the 48, the C2, and at most times the special routemaster version of the 15 – are being withdrawn altogether.

On, and one new route is planned – the 311, from Fulham Broadway to Oxford Circus. This will help plug some of the cuts to the 11, 19 and 22.

So, what does all this mean? Some thoughts:

1) This might not quite be as awful as it initially sounds

TfL says that demand for buses has fallen by around 10 per cent in London in recent years. It predicts it’ll fall further when Crossrail opens, as passengers switch to the new line, or to the tube routes relieved by the new line. So: the idea of taking some unwanted capacity out of the system is not, in itself, terrible.

Striping out unnecessary buses should also improve air quality in some of London’s worst pollution hot spots, and improve traffic flow, hopefully speeding up journeys on those buses that remain. 

A map from the presentation in which TfL explained its plans, showing the reduction in bus numbers on key arteries. Hilariously, notes Darryl Chamberlain, “It no longer produces its own maps, so has had to use one prepared by a bus enthusiast”.

The plans might even free up buses and staff to increase frequencies in outer London where demand hasn’t fallen – though these plans won’t be unveiled until next year and, for reasons I’ll come to below, I’ll believe it when we see it.

2) For many bus users, a lot of these changes will pass almost unnoticed

By my count, I use nine of the affected routes with any regularity – but only three of the changes are things that I’m likely to be at all inconvenienced by. Most of the changes either affect a part of the route I don’t take, or one where there are easy, and pain free alternatives.

This is anecdotal, obviously – perhaps I’m just lucky. But my suspicion is that a lot of these changes will go unnoticed by most passengers. It’s only the sheer number of them happening at once that makes this look like a big deal.

3) The Hopper fare makes this easier...

Once upon a time, if you had to switch buses, you had to pay a second fare. This isn’t true of journeys on the tube or railways – and since bus passengers have, on average, less money than tube passengers, it amounted to a pretty unfair tax on poorer Londoners.

But in January, in what is probably his most notable policy achievement of his two years in office so far, London’s mayor Sadiq Khan changed the rules. Now you can take as many buses as you want within an hour, for a single fare: that means you can switch buses without paying a penalty.

That will have made it easier for TfL to cut routes back: replacing a direct bus journey with one that requires a change no longer means imposing a financial penalty on passengers.


4) ...but not that easy

That’s about where the good news stops, though – because there are reasons other than cost why people prefer direct bus routes. Needing to change buses will be difficult for anyone with any form of mobility impairment, for example. Even for those of us lucky enough not to fall into that category, it’ll be annoying: it’s just easier to stay in one seat for 40 minutes than to get turfed off and have to fight for a new one halfway through.

More than that, from the passengers’ point of view, excess capacity feels quite good a lot of the time: it means your bus may well be nice and empty. Reducing the number of buses along those key corridors will also make those that remain more crowded.

5) The motive is almost certainly financial

Another of Sadiq Khan’s big policy promises was to freeze fares. He made this promise at a time when central government is massively reducing the financial support it gives TfL (the work, Chamberlain notes, of Evening Standard editor George Osborne, back when he was chancellor). And the Hopper fare, while a great idea in many ways, means a further reduction in income.

So: TfL is scrambling for cash: this is why I remain cynical about those new outer London bus routes. I would be amazed if money wasn’t a motivation here, not least because...

6) TfL thinks no one will notice

Any attempt to reduce tube frequencies, let alone close a station, would result in uproar. Hashtag campaigners! Angry people pointing at things in local newspapers! Damning reports on the front of the Evening Standard from the bloke who made it happen!

Buses, though? Their routes change, slightly, all the time. And do you really notice whether your local route comes every 10 minutes or every 12? That’s not to mention the fact that bus passengers, as previously noted, tend to be poorer – and so, less vocal – than tube passengers.

So cuts, and the savings they bring, are much easier to sneak through. TfL probably would have gotten away with it, too, if it hadn’t been for those meddling bloggers.

Although...

7) Scrapping the C2 might be a mistake

The C2 runs from Parliament Hill, through Kentish Town and Camden to Oxford Circus. In other words, it links north London, where a lot of journalists live, to the offices of the BBC and Buzzfeed.

As occasional New Statesman writer James Ball notes, this is probably not the easiest route to quietly shelve.

8) None of this is set in stone

The consultation doesn’t even begin until next month and then will run for six weeks – so all these plans may yet be forgotten. We shall see.

Anyway – here’s Darryl Chamberlain’s original scoop, and here’s some detailed analysis on Diamond Geezer. Please support your local bloggers by reading them.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.

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