On “Transit-Oriented Development”, and the importance of being en route

President Barack Obama tours St Paul's new metro system in 2014, as transportation secretary Anthony Foxx looks on. Image: Getty.

One of the problems with discussions of Transit-Oriented Development – high density development around transport hubs, known as TOD – is that the term sounds much too specialised. 

We hear talk of TODs as a special class of developments, which brings special requirements and possibilities, and perhaps requiring special expertise. In North America, we often hear that a certain development is or isn’t aTOD, as though transit-orientation were not (as it obviously is) a matter of degree.

Moreover, most of the urban development decisions that will determine the future viability of transit are not decisions about TODs. Most of them are not even conscious decisions about transit. The literature of “how to build TODs” is useless in these situations. What people need are simple guidelines about transit that they can keep in the back of their minds, and on their checklists, as they plan ALL kinds of urban development. The same principles could help institutions and individuals decide where to locate.


As a transit planner, I constantly encounter situations where something has been built in a way that precludes quality transit – where I can see that, if it had been built a little differently, transit would have been possible without compromising any of the development’s other goals.

I’ve also dealt with situations where a transit-dependent institution – say, a social-service office catering to low-income people, or an assisted living centre for active seniors – chose to locate in a place where the land was cheap because the transport options were terrible – and then blamed the transit agency for not running buses to their inaccessible site.

These cases are the result of a poor respect and understanding of transit as a background consideration in all urban development. Ultimately, they matter at least as much as the official TODs schemes do in determining the potential for transit in the cities of tomorrow.

If I could put one sentence about transit in the mind of every developer, every land use planner, indeed anyone who makes a decision about where to locate anything, the sentence would be this: Be on the Way. If you want to be sure you’ll have good transit, be on the way from one transit destination to another.

 

An efficient transit line – and hence one that will support good service – connects multiple points; but it’s also reasonably straight, so that it’s perceived as a direct route between any two points on the line. For that reason, good transit geography is any geography in which good transit destinations are on a direct path between other good transit destinations. (Obviously, this is not always a geometrically straight line; it may be a path defined by existing roads or rail corridors that everyone perceives as reasonably direct given the terrain.)

A bad geography is one that indulges in cul-de-sacs on any scale. It sets destinations a little back from the line, so that transit must either bypass them or deviate to them, where deviating means delaying all the other passengers riding through this point.

The same problem arises at many scales:

  • A person who lives at the end of a long cul-de-sac road complains that the bus doesn’t go by her house.
  • A small shopping centre or grocery store sets itself too far back from its street, even though the street is where the transit service is.
  • A university, hospital, business park or other campus-style development positions itself on a hill, often at the end of a road leading only to it, or on a road at the edge of the city where there is nothing further beyond it. This makes the institution look and feel important, but limits the possibilities for transit service because it can only be served by lines that end there.
  • An entire suburb, perhaps one called a Transit-Oriented Development, is located in such a way that no regionally logical transit line will ever get to its town centre, except for routes that go only there.

One of the major failings of Peter Calthorpe’s early 1990s project Laguna West, in Sacramento, is that the town centre is located in a place where no regionally logical transit line could ever serve it. Laguna West still has mediocre transit service because it’s impossible to combine its market with any other markets – which is what you have to do to create an efficient transit line.

Land use planners urgently need simple tools to catch these problems. Until those tools are developed and built into training, they’d do well to just remember one sentence: Be on the Way.

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. All images courtesy of the author.

 
 
 
 

How bad is the air pollution on the average subway network?

The New York Subway. Image: Getty.

Four more major Indian cities will soon have their own metro lines, the country’s government has announced. On the other side of the Himalayas, Shanghai is building its 14th subway line, set to open in 2020, adding 38.5 km and 32 stations to the world’s largest subway network. And New Yorkers can finally enjoy their Second Avenue Subway line after waiting for almost 100 years for it to arrive.

In Europe alone, commuters in more than 60 cities use rail subways. Internationally, more than 120m people commute by them every day. We count around 4.8m riders per day in London, 5.3m in Paris, 6.8m in Tokyo, 9.7m in Moscow and 10m in Beijing.

Subways are vital for commuting in crowded cities, something that will become more and more important over time – according to a United Nations 2014 report, half of the world’s population is now urban. They can also play a part in reducing outdoor air pollution in large metropolises by helping to reduce motor-vehicle use.

Large amounts of breathable particles (particulate matter, or PM) and nitrogen dioxide (NO2), produced in part by industrial emissions and road traffic, are responsible for shortening the lifespans of city dwellers. Public transportation systems such as subways have thus seemed like a solution to reduce air pollution in the urban environment.

But what is the air like that we breathe underground, on the rail platforms and inside trains?

Mixed air quality

Over the last decade, several pioneering studies have monitored subway air quality across a range of cities in Europe, Asia and the Americas. The database is incomplete, but is growing and is already valuable.

Subway, Tokyo, 2016. Image: Mildiou/Flickr/creative commons.

For example, comparing air quality on subway, bus, tram and walking journeys from the same origin to the same destination in Barcelona, revealed that subway air had higher levels of air pollution than in trams or walking in the street, but slightly lower than those in buses. Similar lower values for subway environments compared to other public transport modes have been demonstrated by studies in Hong Kong, Mexico City, Istanbul and Santiago de Chile.

Of wheels and brakes

Such differences have been attributed to different wheel materials and braking mechanisms, as well as to variations in ventilation and air conditioning systems, but may also relate to differences in measurement campaign protocols and choice of sampling sites.

Second Avenue Subway in the making, New York, 2013. Image: MTA Capital Construction/Rehema Trimiew/Wikimedia Commons.

Key factors influencing subway air pollution will include station depth, date of construction, type of ventilation (natural/air conditioning), types of brakes (electromagnetic or conventional brake pads) and wheels (rubber or steel) used on the trains, train frequency and more recently the presence or absence of platform screen-door systems.

In particular, much subway particulate matter is sourced from moving train parts such as wheels and brake pads, as well as from the steel rails and power-supply materials, making the particles dominantly iron-containing.


To date, there is no clear epidemiological indication of abnormal health effects on underground workers and commuters. New York subway workers have been exposed to such air without significant observed impacts on their health, and no increased risk of lung cancer was found among subway train drivers in the Stockholm subway system.

But a note of caution is struck by the observations of scholars who found that employees working on the platforms of Stockholm underground, where PM concentrations were greatest, tended to have higher levels of risk markers for cardiovascular disease than ticket sellers and train drivers.

The dominantly ferrous particles are mixed with particles from a range of other sources, including rock ballast from the track, biological aerosols (such as bacteria and viruses), and air from the outdoors, and driven through the tunnel system on turbulent air currents generated by the trains themselves and ventilation systems.

Comparing platforms

The most extensive measurement programme on subway platforms to date has been carried out in the Barcelona subway system, where 30 stations with differing designs were studied under the frame of IMPROVE LIFE project with additional support from the AXA Research Fund.

It reveals substantial variations in particle-matter concentrations. The stations with just a single tunnel with one rail track separated from the platform by glass barrier systems showed on average half the concentration of such particles in comparison with conventional stations, which have no barrier between the platform and tracks. The use of air-conditioning has been shown to produce lower particle-matter concentrations inside carriages.

In trains where it is possible to open the windows, such as in Athens, concentrations can be shown generally to increase inside the train when passing through tunnels and more specifically when the train enters the tunnel at high speed.

According to their construction material, you may breath different kind of particles on various platforms worldwide. Image: London Tube/Wikimedia Commons.

Monitoring stations

Although there are no existing legal controls on air quality in the subway environment, research should be moving towards realistic methods of mitigating particle pollution. Our experience in the Barcelona subway system, with its considerable range of different station designs and operating ventilation systems, is that each platform has its own specific atmospheric micro environment.

To design solutions, one will need to take into account local conditions of each station. Only then can researchers assess the influences of pollution generated from moving train parts.

The ConversationSuch research is still growing and will increase as subway operating companies are now more aware about how cleaner air leads directly to better health for city commuters.

Fulvio Amato is a tenured scientist at the Spanish National Research CouncilTeresa Moreno is a tenured scientist at the Institute of Environmental Assessment and Water Research (IDAEA), Spanish Scientific Research Council CSIC.

This article was originally published on The Conversation. Read the original article.