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.

 
 
 
 

The Tory manifesto promises to both increase AND decrease the rate of housebuilding

Housing secretary Robert Jenrick. Image: Getty.

In his 2014 Mansion House speech, the then-chancellor George Osborne expressed with uncharacteristic honesty the motives at the heart of how the Conservatives see British housing politics: “The British people want our homes to go up in value, but also remain affordable; and we want more homes built, just not next to us.”

Five years later these contradictions remain unreconciled and present in their manifesto, which contains two different and contradictory – but clearly extensively targeted and focus-grouped – sets of policies.

The Conservatives have two housing targets. The first is to make significant progress to hitting “our target of 300,000 houses built a year by the mid-2020s”. The second is their aim to build “at least a million new homes” during the next parliament, which implies a target of 200,000 homes a year. This is not only 100,000 lower than their initial target but also lower than the current rate of housebuilding: 213,660 new homes a year. They have therefore implied at separate points in the same manifesto that they intend to simultaneously increase and decrease the rate of housebuilding.  

There are similar conflicts in their approach to planning. They intend to make the “planning system simpler” while simultaneously aiming to introduce community-led design standards for development and planning obligations to provide infrastructure for the local community.

None of this is unsurprising, The Tories don’t seem to know if they want to build more houses or not – so of course they don’t know whether they wish to make it easier or harder to do so.  

Politicians like obfuscation on housing policy to placate NIMBY voters. Take for example prospective Conservative MP and ‘environmentalist’ Zac Goldsmith’s crusade to save treasured local car parks. The manifesto can equally be accused of pandering to NIMBY instincts, protecting their shire voters from all housing, including ones they might actually need or want, by promising to protect the greenbelt.  

Instead, Conservatives intend to foist development on Labour-leaning inner-city communities and prioritising brownfield development and “urban regeneration”. This requires massive, infeasible increases in proposed density on brownfield sites – and research by Shelter has shown there are simply not enough brownfield sites in cities like London. Consequently, it is not clear how such a policy can co-exist with giving these inner-city communities rights on local design. Perhaps they intend to square that circle through wholesale adoption of YIMBY proposals to let residents on each street opt to pick a design code and the right to turn their two-storey semi-detached suburban houses into a more walkable, prettier street of five-storey terraces or mansion blocks. If so, they have not spelt that out. 

Many complain of NIMBYism at a local level and its toxic effects on housing affordability. But NIMBYism at the national level – central government desire to restrict housebuilding to make house prices rise – is the unspoken elephant in the room. After all, 63 per cent of UK voters are homeowners and price rises caused by a housing shortage are hardly unpopular with them. 


There is anecdotal evidence that protecting or inflating the value of homeowners’ assets is central to Conservative strategy. When George Osborne was criticised for the inflation his help to buy policy caused within the housing market, he allegedly told the Cabinet: “Hopefully we will get a little housing boom, and everyone will be happy as property values go up”. More recently Luke Barratt of Inside Housing noted that most Conservatives he spoke to at the 2018 party conference were scared “they’d be punished by their traditional voters if the values of their homes were to fall”. He was told by a Conservative activist at the conference that, “If you build too many houses, you get a Labour government”.

But the senior figures in the Conservative Party are painfully aware that the continuing housing shortage presents major long-term problems for the Party. As the manifesto itself acknowledges: “For the UK to unleash its potential, young people need the security of knowing that homeownership is within their reach.” Perpetual increases in house prices are incompatible with this goal. The problem has greatly contributed to the Conservatives’ severe unpopularity with a younger generation priced out of decent accommodation. 

Equally, there is increasing evidence that ‘gains’ from rising house prices are disproportionately concentrated in the south of England.  The differences in housing costs between regions greatly reduce labour mobility, suppressing wage growth in the north and midlands, which in turn leads to greater regional inequality. The policy of coddling southern homeowners at the expense of the economic well-being of other regions is a major long-term stumbling block to Conservative desires to make inroads into the ‘red wall’ of Leave-voting labour seats outside the south.

Before dealing with the issue of where housing should go, you must decide whether you want to build enough housing to reduce the housing crisis. On this issue, the Conservative response is, “Perhaps”. In contrast, even though they may not know where to put the necessary housing, the Labour Party at least has a desire in the abstract to deal with the crisis, even if the will to fix it, in reality, remains to be seen. 

Ultimately the Conservative Party seems to want to pay lip service to the housing crisis without stopping the ever-upward march of prices, underpinned by a needless shortage. Osborne’s dilemma – that the will of much of his party’s voter base clashes with the need to provide adequate housing – remains at the heart of Conservative housing policy. The Conservatives continue to hesitate, which is of little comfort to those who suffer because of a needless and immoral housing shortage.

Sam Watling is the director of Brighton Yimby, a group which aims to solve Brighton’s housing crisis while maintaining the character of the Sussex countryside.