Parking slots are like toilets (according to conventional parking planning)

[Update: Looking for more parking policy information?  
Try Reinventing Parking.]

Planning systems treat parking and toilets in very similar ways and for similar reasons (such as to deter people from 'doing it in the streets'). Is this just a funny observation? I guess it is quite funny but I also have a serious point.

Planning toilets like we plan for fire-escapes, elevators and plumbing does work quite well (mostly). However, planning for parking like we plan for toilets is problematic. Below, I list ways that conventional planning does in fact treat parking and toilets the same. Then I highlight key differences which make planning parking like toilets seem like a very bad idea.

First, a list of how parking and toilets are (conventionally) planned in very similar ways:

1. Both are treated as an essential ancillary service that every building will need.
   
2. It is usually assumed that no fee (or a token fee at most perhaps) will be charged. Remember, we are talking about the conventional approach to parking policy here. Some jurisdictions even ban fees for such facilities.
   
3. There is thus little direct return on the investments. So the private sector would under-provide them unless forced to. To the rescue come regulations in the form of parking or toilet requirements in planning or building codes.
   
4. As mentioned above, one rationale for requiring them with buildings is so people won't have to use the streets (or not too much anyway).
   
5. Another reason they are required with buildings is so people don't freeload on the facilities of neighbouring buildings. In parking this is called "spillover". This might be apt for toilets too, come to think of it.
   
6. Demand for these facilities is usually assumed in the regulations to be associated with specific premises rather than a whole neighbourhood.
   
7. When the buildings can't provide enough (as in old neighbourhoods for example), local governments may step in and provide some. Otherwise people (or at least high-end customers) may avoid the area.
   
8. There are provisions in the codes to ensure access for people with disabilities.
   
9. Sometimes facilities for females are specified for both. OK, this one is rare for parking but I couldn't resist putting it in.
   
10. The planning system assumes it can predict demand and therefore set reasonable and accurate requirements. In both cases, getting it wrong can cause problems.
    
11. The standards can end up being very complicated. Singapore's parking standards (pdf) list about 50 different building uses, each with its own parking standard. The American Restroom Association (ARA) website reveals several competing models for 'restroom codes' (including: the 2003 Uniform Plumbing Code (UPC) published by the International Association of Plumbing and Mechanical Officials and the 2000 International Plumbing Code (IPC) published by the International Code Council (ICC). Their provisions look remarkably similar to parking standards. For example, the International Plumbing Code includes:
    "403.1 Minimum number of fixtures.  Plumbing fixtures shall be provided for the type of occupancy and in the minimum number shown in Table 403.1. Types of occupancies not shown in Table 403.1 shall be considered individually by the code official."
    
12. In both cases, old buildings built before modern standards were enacted are treated differently ('grandfathered', so that they must only comply with the rules at the time they were built). However, the new codes may kick in if the owner wants to do anything that requires planning permission (such as a change of use).
    
13. A distinction is made in both between private facilities and those that are available to the public. These may be treated differently in the standards. There is often conflict over whether the facilities in any particular premises should be open to the public. 

BUT the analogy breaks down. Parking differs from toilets in crucial ways (besides the obvious!). 

1. It is much more difficult to predict parking demand than to predict toilet demand (which itself is not easy). The human need to expel waste changes little (except when beer is consumed in large quantities perhaps). The demand for parking can change enormously over time as car ownership changes and as mode choices shift.
   
2. Everyone needs toilets. Only car users need parking. (But conventional parking policy assumes that 'car users' = 'everyone')
   
3. Parking takes a lot more space than toilets. Forgive me for stating the obvious here. It is common for American suburban office parks to be required to have as much parking space as they have floor space for other uses. Buildings in Kuala Lumpur (see the picture) or Bangkok often have a third or more of their floors devoted to parking. Parking standards often dramatically limit the density that is feasible on a site.
   
4. Required parking is extremely costly. Even the most lavish provision of toilet space does not threaten the feasibility of building projects.
   
5. Even the most generous provision of toilets would not dramatically influence people's behaviour or discourage us from using less harmful alternatives. There is no toilet analogy for walking, cycling and public transport. No toilet alternatives get starved of users, of investment or are rendered unpleasant and unsafe as a result of excessive toilet provision.
   
6. It may be reasonable to prohibit charging for toilet use (as some American jurisdications do). Failing to charge efficient prices is much more problematic for parking (as Donald Shoup spent 700 pages or so explaining).
   
7. Parking in the streets can be regulated and managed to render it less problematic, whereas public urination or defacation are never acceptable public policy outcomes.
   
8. Toilet requirements are rarely (if ever?) so onerous that they freeze redevelopment or reuse of old buildings in inner city areas. Parking standards often do so (and in the process they can worsen inner urban blight).
   

These differences highlight problems with conventional parking policy. It is probably NOT such a great idea to plan parking like we plan toilets.

Does this analogy work for you? Does it help you think about parking policy? Can you help me to improve these lists? Are some of the points weaker than others? Have I missed any?


*  Some background: I have been developing this analogy in recent months and included it in several talks about my parking research (first in Ahmedabad, then in Singapore and recently in Manila). A few audience members in Manila said, "I want to use that!". That response has prompted me to get down to posting it here.

I have been blunt in this post and mostly said 'toilets' rather than use euphemisms like restrooms, bathrooms, WCs, etc.