Will London’s Ultra Low Emissions Zone improve the city’s health?

London. We think. Not sure, actually. Image: Getty.

A new Ultra Low Emission Zone (ULEZ) is being introduced in London, to reduce harmful emissions from traffic and improve air quality. Those who drive polluting vehicles into the city centre will face a daily charge – £12.50 for cars, motorcycles and vans, and £100 for lorries, buses and coaches – on top of the existing congestion charge. By October 2021, the scheme will expand to cover an area 18 times larger.

The rationale for the ULEZ is clear: large numbers of people are living in areas with pollution levels well above the legal limits set by the European Union (EU). These limits are based on detailed evidence about the impacts of air pollution on people’s health – which can cause everything from short term effects like worsening asthma symptoms, to a loss of healthy years of life in the longer term.

Other cities across the UK and beyond will be watching closely, as London’s ULEZ is effectively a test bed to gauge the effectiveness of such schemes at clearing up air pollution and improving the health of residents.

Major health problems

Over recent years, several London-based studies have shown that the city’s air pollution is associated with increased respiratory and cardiovascular hospital admissions, increases in daily deaths, stroke risk and low birth weights, as well as reduced lung volumes in children, dementia among the elderly, and poor mental health in children and adolescents.

Clearly, the polluted air that people breathe in London is having profound effects on their health, throughout their entire lives. So, while some people will lose out – for example, those who need to drive in central London for work – that should be weighed against the clear need for action to reduce pollution, on health grounds.

As well as the current health concerns, there are legal reasons why London authorities have introduced the new charge. Much of the area covered by the ULEZ often exceeds the annual EU limit for nitrogen dioxide (NO₂) – especially near roads, where diesel vehicles are a major source of the gas. The EU annual limit for NO₂ is 40μg/m³ (that’s micrograms per metre cubed).

A map of annual mean NO₂ pollution levels across London, based on data from 2013. Areas coloured from yellow through to red exceed annual targets. Image: London Air/KCL.

There are also other legal limits set by the EU for airborne particulate matter of various sizes. If you consider fine particles – often referred to as PM₂.₅ (generally less than 2.5 microns in diameter) – then the picture looks better. Most of London meets the EU’s annual limit for PM₂.₅, which is 25μg/m³.

But numerous studies have shown there are clear health impacts below this concentration, and the World Health Organisation (WHO) recommends that an annual target of 10μg/m³ would be best to protect people’s health. If this lower annual exposure limit was to be used, many areas across London would exceed it – just as they currently do with NO₂.

Medicine worth taking

The evidence shows that diesel exhaust emissions are the major driver of poor health outcomes due to air pollution. That doesn’t mean that other pollutant sources, such a biomass burning, agriculture, industry, or particles derived from brake and tyre wear, are not important – but it makes sense for cities to make reducing diesel emissions a priority. Will it work, though?

The ULEZ, like the Low Emission Zone before it, is designed to encourage the uptake of newer, low emission vehicles both by businesses and the general public with the aim of reducing air pollution in the target area. Current evidence does suggest that air pollution concentrations are falling in London as a result of several measures, such as the Low Emission Zone, but these improvements still need to be accelerated to deliver health benefits.


Since the ULEZ targets all vehicles, modelling commissioned by the Greater London Authority predicts that it will have significant impact on air quality, compared with earlier policies, which focused on restricting only certain types of vehicles. But this projection still needs to be validated.

If the ULEZ is the equivalent to the treatment to the air pollution problem, then like a clinical drug trial it requires independent evaluation, measuring both the changes in pollution concentration, and health improvements among Londoners.

Work is already ongoing to address these issues, such as the Children’s Health in London and Luton (CHILL) project, which is examining children’s respiratory health and lung growth across the introduction of the ULEZ. But further work evaluating this scheme is needed, to keep ensuring that policies are developed based on evidence – and prove to the public that this is a medicine worth taking.

The Conversation

Ian Mudway, Lecturer in Respiratory Toxicology, King's College London.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

To build its emerging “megaregions”, the USA should turn to trains

Under construction: high speed rail in California. Image: Getty.

An extract from “Designing the Megaregion: Meeting Urban Challenges at a New Scale”, out now from Island Press.

A regional transportation system does not become balanced until all its parts are operating effectively. Highways, arterial streets, and local streets are essential, and every megaregion has them, although there is often a big backlog of needed repairs, especially for bridges. Airports for long-distance travel are also recognized as essential, and there are major airports in all the evolving megaregions. Both highways and airports are overloaded at peak periods in the megaregions because of gaps in the rest of the transportation system. Predictions for 2040, when the megaregions will be far more developed than they are today, show that there will be much worse traffic congestion and more airport delays.

What is needed to create a better balance? Passenger rail service that is fast enough to be competitive with driving and with some short airplane trips, commuter rail to major employment centers to take some travelers off highways, and improved local transit systems, especially those that make use of exclusive transit rights-of-way, again to reduce the number of cars on highways and arterial roads. Bicycle paths, sidewalks, and pedestrian paths are also important for reducing car trips in neighborhoods and business centers.

Implementing “fast enough” passenger rail

Long-distance Amtrak trains and commuter rail on conventional, unelectrified tracks are powered by diesel locomotives that can attain a maximum permitted speed of 79 miles per hour, which works out to average operating speeds of 30 to 50 miles per hour. At these speeds, trains are not competitive with driving or even short airline flights.

Trains that can attain 110 miles per hour and can operate at average speeds of 70 miles per hour are fast enough to help balance transportation in megaregions. A trip that takes two to three hours by rail can be competitive with a one-hour flight because of the need to allow an hour and a half or more to get to the boarding area through security, plus the time needed to pick up checked baggage. A two-to-three-hour train trip can be competitive with driving when the distance between destinations is more than two hundred miles – particularly for business travelers who want to sit and work on the train. Of course, the trains also have to be frequent enough, and the traveler’s destination needs to be easily reachable from a train station.

An important factor in reaching higher railway speeds is the recent federal law requiring all trains to have a positive train control safety system, where automated devices manage train separation to avoid collisions, as well as to prevent excessive speeds and deal with track repairs and other temporary situations. What are called high-speed trains in the United States, averaging 70 miles per hour, need gate controls at grade crossings, upgraded tracks, and trains with tilt technology – as on the Acela trains – to permit faster speeds around curves. The Virgin Trains in Florida have diesel-electric locomotives with an electrical generator on board that drives the train but is powered by a diesel engine. 

The faster the train needs to operate, the larger, and heavier, these diesel-electric locomotives have to be, setting an effective speed limit on this technology. The faster speeds possible on the portion of Amtrak’s Acela service north of New Haven, Connecticut, came after the entire line was electrified, as engines that get their power from lines along the track can be smaller and much lighter, and thus go faster. Catenary or third-rail electric trains, like Amtrak’s Acela, can attain speeds of 150 miles per hour, but only a few portions of the tracks now permit this, and average operating speeds are much lower.

Possible alternatives to fast enough trains

True electric high-speed rail can attain maximum operating speeds of 150 to 220 miles per hour, with average operating speeds from 120 to 200 miles per hour. These trains need their own grade-separated track structure, which means new alignments, which are expensive to build. In some places the property-acquisition problem may make a new alignment impossible, unless tunnels are used. True high speeds may be attained by the proposed Texas Central train from Dallas to Houston, and on some portions of the California High-Speed Rail line, should it ever be completed. All of the California line is to be electrified, but some sections will be conventional tracks so that average operating speeds will be lower.


Maglev technology is sometimes mentioned as the ultimate solution to attaining high-speed rail travel. A maglev train travels just above a guideway using magnetic levitation and is propelled by electromagnetic energy. There is an operating maglev train connecting the center of Shanghai to its Pudong International Airport. It can reach a top speed of 267 miles per hour, although its average speed is much lower, as the distance is short and most of the trip is spent getting up to speed or decelerating. The Chinese government has not, so far, used this technology in any other application while building a national system of long-distance, high-speed electric trains. However, there has been a recent announcement of a proposed Chinese maglev train that can attain speeds of 375 miles per hour.

The Hyperloop is a proposed technology that would, in theory, permit passenger trains to travel through large tubes from which all air has been evacuated, and would be even faster than today’s highest-speed trains. Elon Musk has formed a company to develop this virtually frictionless mode of travel, which would have speeds to make it competitive with medium- and even long-distance airplane travel. However, the Hyperloop technology is not yet ready to be applied to real travel situations, and the infrastructure to support it, whether an elevated system or a tunnel, will have all the problems of building conventional high-speed rail on separate guideways, and will also be even more expensive, as a tube has to be constructed as well as the train.

Megaregions need fast enough trains now

Even if new technology someday creates long-distance passenger trains with travel times competitive with airplanes, passenger traffic will still benefit from upgrading rail service to fast-enough trains for many of the trips within a megaregion, now and in the future. States already have the responsibility of financing passenger trains in megaregion rail corridors. Section 209 of the federal Passenger Rail Investment and Improvement Act of 2008 requires states to pay 85 percent of operating costs for all Amtrak routes of less than 750 miles (the legislation exempts the Northeast Corridor) as well as capital maintenance costs of the Amtrak equipment they use, plus support costs for such programs as safety and marketing. 

California’s Caltrans and Capitol Corridor Joint Powers Authority, Connecticut, Indiana, Illinois, Maine’s Northern New England Passenger Rail Authority, Massachusetts, Michigan, Missouri, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Texas, Vermont, Virginia, Washington, and Wisconsin all have agreements with Amtrak to operate their state corridor services. Amtrak has agreements with the freight railroads that own the tracks, and by law, its operations have priority over freight trains.

At present it appears that upgrading these corridor services to fast-enough trains will also be primarily the responsibility of the states, although they may be able to receive federal grants and loans. The track improvements being financed by the State of Michigan are an example of the way a state can take control over rail service. These tracks will eventually be part of 110-mile-per-hour service between Chicago and Detroit, with commitments from not just Michigan but also Illinois and Indiana. Fast-enough service between Chicago and Detroit could become a major organizer in an evolving megaregion, with stops at key cities along the way, including Kalamazoo, Battle Creek, and Ann Arbor. 

Cooperation among states for faster train service requires formal agreements, in this case, the Midwest Interstate Passenger Rail Compact. The participants are Illinois, Indiana, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, and Wisconsin. There is also an advocacy organization to support the objectives of the compact, the Midwest Interstate Passenger Rail Commission.

States could, in future, reach operating agreements with a private company such as Virgin Trains USA, but the private company would have to negotiate its own agreement with the freight railroads, and also negotiate its own dispatching priorities. Virgin Trains says in its prospectus that it can finance track improvements itself. If the Virgin Trains service in Florida proves to be profitable, it could lead to other private investments in fast-enough trains.

Jonathan Barnett is an emeritus Professor of Practice in City and Regional Planning, and former director of the Urban Design Program, at the University of Pennsylvania. 

This is an extract from “Designing the Megaregion: Meeting Urban Challenges at a New Scale”, published now by Island Press. You can find out more here.