How can compact cities keep house prices under control?

Southwark (left): surprisingly un-dense. Image: Getty.

Islington is the most densely populated are in the United Kingdom – yet wandering around the quiet streets of the north London borough, it is difficult to appreciate just how many people live there. Handsome terraces, elegant squares and a plethora of parks disguise the fact that there are nearly 14,000 people per km2.

By comparison, anyone passing through Southwark, on the other side of the Thames, is immediately aware of the crowds of people who live and work in the area. New glass towers loom over the major roads, while older council housing squat heavily on the back streets. Cars crawl through the famously congested roundabout and the air is heavy with pollution.

Yet Southwark has fewer than 10,000 residents per km2. This means it is significantly less dense than many of its more desirable northern neighbours: Kensington and Chelsea, Hackney, Camden, Tower Hamlets and, of course, Islington.

Measuring the benefits of urban density

Increasing the number of people living and working in an area can generate huge benefits for a city. Productivity rises as people spend less time and money travelling, and can share knowledge and ideas more freely. Businesses can reduce their production costs when they have access to a greater choice of specialised suppliers and workers. And it’s cheaper to provide services such as health care, waste collection and buses when more people can use them.

For the first time, researchers have estimated the monetary value of these benefits to urban residents. Their findings have just been published in the first working paper from the Coalition for Urban Transitions, a network of over twenty organisations committed to enhancing the economic, social and environmental performance of cities.

Drawing on more than 300 academic papers, Demystifying Compact Urban Growth: Evidence from 300 Studies Across the World demonstrates that increasing population density generates significant economic returns. The authors find that a 10 per cent increase in the number of people living and working in an area enhances productivity by approximately £54 per person per year. Better access to jobs is worth another £48, while improved access to services and amenities is valued at £38. Increased population density is also associated with better environmental outcomes, including preservation of green space and greater energy efficiency.

All other things being equal, this suggests that compact cities like Hong Kong, New York and Paris are likely to be richer and more sustainable than sprawling cities such as Houston or Melbourne.

Managing the risks of urban density

A more compact city is not a silver bullet: there are also risks associated with increasing population density. Careful urban planning is required to mitigate these risks, and deliver the potential economic and environmental benefits.

First, a 10 per cent increase in the number of people living and working in an area can lead to more congestion, with an estimated cost of £27 per person a year. Significant investment in public transport, cycling lanes and pedestrian walkways is essential to ensure that people can move around the city without cars.

Second, this increase in density increases housing costs by £186 per person per year. Such growth in house prices might benefit people who own their own homes or rent out property – but it will be a challenge for renters. As low-income households are more likely to rent, there is a risk that compact city policies will exacerbate inequality within cities.

Governments can avoid an increase in housing costs through policies to increase housing supply. A steady flow of new homes coming on to the market can have a downward effect on housing prices, which may outweigh the upward effect caused by increasing population density.

Lessons from London

In the 19th century, the city of London undertook a series of extraordinarily ambitious urban infrastructure projects that continue to shape the city. The world’s first underground railway was opened in 1863; today, the London Underground carries an average five million passengers per day.

In the 1860s, a vast network of sewers and drains were constructed to serve the three million people living in London. These pipes ended the waves of dysentery, typhoid and cholera that devastated the city, and continue to be used by over 8m Londoners. These far-sighted investments enabled people to live and work in close proximity to each other, helping to sustain London’s population and economic growth for over a century.

A walk through London today suggests that the city is now struggling to manage population density. Despite Crossrail, the proliferation of cycling lanes and iconic red buses on every street, many people continue to depend on cars. As a result, London has the worst air pollution in Western Europe. A normal day’s exposure is equivalent to smoking 15 cigarettes.

The problems extend from transport to housing. House prices in Islington have doubled in the last decade, a period when real wages have stagnated. The soaring property prices are the favourite topic of struggling renters or prospective buyers. The city needs to build over 50,000 homes a year to keep up with population growth, while redressing decades of neglect in the existing housing stock.  The failures of London’s housing policy were made all too clear with shocking fire that devastated Grenfell Tower and the lives of its residents.

Thousands of people move to London every year for the economic and social opportunities associated with this extraordinary city. Its dynamism is due in no small part to its high population density. However, the city’s strained transport system and spiralling house prices underscore the importance of strategic government intervention to manage the risks of crowding so many people into such a small area. Large-scale investment in public transport and housing are essential to ensure that compact cities are also liveable and affordable.

Sarah Colenbrander is a researcher with the International Institute for Environment and Development (IIED) and senior economist with the Coalition for Urban Transitions. The working paper, Demystifying Compact Urban Growth: Evidence from 300 Studies Across the World, was prepared for the Coalition for Urban Transitions by the Organisation for Economic Cooperation and Development (OECD).


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.