Two weeks ago I wrote of Enrique Peñalosa's call to release our cities' precious roadspace of cars for the good of busways, cycleways, pedestrians and street life in general. At the same time, the Institute for Transportation and Development Policy (ITDP), the Pan-American think tank that inspired many of the initiatives Peñalosa promotes, was releasing research on how to achieve this through an area of policy often overlooked: parking policy.
Peñalosa reminded his audience that "traffic is not caused by the number of cars; it's caused by the number of roads". For several decades, governments sought to build longer highways, wider freeways, hoping to relieve congestion with new roads for commuters to zip along, and it never worked. The perception of better roads leads to a disproportionate increase in the number of trips and journeys that commuters take by car.
One alternative sought, most famously in London, is congestion charging. Authorities set up camera installations around their central business districts, scanning number plates of passing cars and charging each vehicle that entered the zone eight, now ten, pounds per day. Rather than restrict vehicle usage by measures like number-plate rationing, the charging system uses a market-based approach to disincentivise commuters from bringing their cars into the city.
The other alternative is to make it harder and harder to park one's car. ITDP's report, Europe's Parking U-Turn: from accommodation to regulation, demonstrates how several governments are turning to this option, following a similar study conducted in US cities last year. As its authors, Michael Kodransky and Gabrielle Hermann write, "every car trip begins and ends in a parking space, so parking regulation is one of the best ways to regulate car use."
They note how government attitudes to parking have evolved in parallel to their attitudes to highways. "For much of the twentieth century, cities in Europe, like cities in the rest of the world, used parking policy mainly to encourage the construction of additional off-street parking, hoping to ease a perceived shortage of parking."
This just created additional incentives to drive cars into city centres, yet "no matter how many new parking garages and motorways they built, the traffic congestion only grew worse, and as much as 50% of traffic congestion was caused by drivers cruising around in search of a cheaper parking space."
There are three main sites where cities can intervene with parking policy to reduce car use. The first are economic incentives, of the kind that congestion charging tried to produce.
Getting the prices right on parking stations and meters is an important aspect of this, and the authors offer a powerfully simple guiding principle. "Traffic experts know 15% of parking spaces unoccupied is optimal from the perspective of minimizing the time people spend cruising for parking." To know where to set the prices, they just need to be increased until no more than 85% are occupied at any time. The high prices move large numbers of drivers towards other transport options, while a quality of service is maintained for those who still require their cars.
Prices should vary between different locations, and at different times of the day, to maximise revenue without compromising service, and the supply and pricing of both on-street bays and off-street parking stations should be coordinated. To reduce emissions further, several boroughs in London charge different rates for residential parking permits depending on the emission levels of the car being registered.
The second site of intervention is regulatory mechanisms. Historically, town plans required developers to provide minimum levels of parking off-site, encouraging an oversupply of basement parking in thousands of inner-city properties. Many cities now switch to setting parking maximums. Zurich has a sophisticated policy that "only allows developers to build new parking spaces if the surrounding roads can absorb additional traffic without congestion, and the air can handle additional pollution without violating ambient air quality norms." Dutch cities set three grades of parking maximums that differ depending on the level of public transit access available to the neighbourhood. Only the areas least accessible to existing public transit may build substantial numbers of parking spaces, yet even those remain capped.
The third site of invention is physical design. To make it impossible for drivers to take their chances with illegal parking, Paris and Madrid have each spent millions on bollards that prevent cars from mounting the kerb. Copenhagen replaced hundreds of spaces by replacing kerbside parking with wider footpaths and bus lanes.
To capture further benefits from these policies, cities can now avail of a mature market in service contracting and technologies that improve the capture of revenues, reduce fee evasion, and that can manage fluctuating demand and regulate prices accordingly.
The positive sign is the creativity with which new policies are being explored. Nottingham has charged companies an annual tax on car spaces provided for employees. Stockholm has stopped demarcating individual bays so that smaller cars can squeeze together more efficiently. Parking meters in Versailles feature blinking lights that alert traffic wardens to cars that have overstayed their fifteen minutes. And Hamburg require companies to provide less parking if a larger number of their employees buy public transit passes.
Not all of these ideas will stick; some may prove too cumbersome and costly to maintain, and a few policy tools will begin to stand out. But it is valuable that so many cities experiment with different options, and that researchers like the ITDP keep bringing all of these to light.