Wednesday, November 28, 2012

Does removing on-street parking reduce congestion?

Wednesday, November 28, 2012


The answer is obviously yes, you say? Not so fast. 

Seeing a virtue in removing all parking from streets is a widespread notion. I have seen it in Indonesia recently, as well as in India and China.  Singapore has already removed parking from most streets that have any importance for traffic. And of course, the idea that roadways are for traffic, not parking, has long been a mantra for the design of car-oriented landscapes across North America or Australasia.

The truth is that removing parking from a street MAY NOT help traffic flow.

I should first say that, yes, parking might be causing congestion. But in most cases, the real problem is  parking saturation (which is usually the result of weak on-street parking management).

In other words, it is not necessarily parking itself that is the problem, but full parking! Parking can seem saturated at occupancies above about 85%. This causes congestion by encouraging:
- double-parking,
- waiting in the traffic lanes, and
- slowly searching for parking (also called 'cruising for parking').

Parking saturation causes problems on parts of Jalan Suryakencana in Bogor, Indonesia

Of course, maybe these phenomena would disappear if there is no parking at all. But you don't have to completely eliminate on-street parking to solve these problems. Better to solve the parking saturation which is causing the problems. How can you do that? Improve on-street parking management, especially via efficient pricing

But suppose you really just want the on-street space that is currently used by parking to be given to traffic flow? 

Could converting a parking lane into a traffic lane ease congestion? Maybe, but ONLY if parking is really the thing that is limiting road capacity. Many streets have other important constraints on road capacity.

These often include the capacity of the intersections. If the roadway width is the same mid-block and at intersections, then the mere presence of a parking lane at mid-block is unlikely to cause congestion. And turning that parking lane into a traffic lane will do nothing for your traffic flow. Assuming you have already tackled any parking saturation (discussed above), then the intersection is the limiting factor for traffic, not all that mid-block parking space.

Now removing parking might reduce friction a little. But occasional parking friction is not what causes major bouts of peak-time congestion. Such friction just slows the traffic a little, which might be a GOOD THING in a multi-use street.

In Indonesia and many other middle-income or low-income countries, public transport drivers, taxis and taxi-like modes often behave in ways that have a big impact on traffic, especially at intersections. If that is the case, then removing parking will probably not make traffic move any faster. Here is a video showing that parking is likely only a part of the congestion problem for Jalan Suryakencana in Bogor (in Indonesia), a busy shopping street with old shophouses along it. Yet, national policy in Indonesia calls for parking to be removed from such streets for the sake of traffic flow.


And don't forget, even if you do sometimes get more traffic capacity by removing parking, are you really sure that is what you want? 

The relief may only be temporary, after all, since latent demand tends to fill the new road space before long. Furthermore, removing parking from a vibrant inner-city shopping street for the sake of traffic flow is unlikely to help that inner city stay attractive and competitive with businesses in outer areas, such as shopping malls. You want such streets to be places to COME TO, not RUSH THROUGH.

So is removing on-street parking always a bad idea? Of course not! 

It may often be a great idea to remove some parking for the sake of other priorities besides parking and traffic flow. These include bus lanes, bicycle facilities, drop-off/pick-up points, loading/unloading, taxi stops, pocket parks, walking space, etc. Any or all of these might be a good idea depending on the situation. They tend to build the accessibility and attractiveness of the area rather than focusing just on moving vehicles.  

Bottom line: Please be cautious when you hear someone calling for on-street parking to be completely removed, especially if it is for the sake of traffic flow. 


Note: As you may have noticed, this post was written with cities in Indonesia, India and China in mind. But the issues apply much more widely of course. 
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