February 17, 2009

Should we prioritize walking, biking and public transport?

Well, we should encourage all of these things. I wish I had more room for titles, for what I really want to ask is: should these be considered more important than electrification of light vehicles (cars, etc.)?

The answer to that is no.

Walking can't replace light vehicles quickly. In the long run localization will help, but vehicles can be replaced 10x as fast as housing: half of all light vehicle miles driven come from vehicles that are less than 6 years old.

Ask anyone who's bicycled for any sustained distance and time - it's not very safe in most places. To be safe, biking needs large infrastructural investments in the form of dedicated, physically separated and protected lanes. Further, exercise is certainly good for you, but renewably powered electric vehicles are much lower C02, due to the FF-intensivity of our food supply.

Electric bikes are probably the very lowest CO2 transportation. Bicycling purists tend to object to them - I guess it's due to excessive emphasis on exercise, and a lack of awareness of the CO2-related benefits of electricity vs food calories. They're much more accessible for the partially disabled, and people who can't arrive at work all sweaty. The Chinese are moving to electric bicycles as well as electric cars. That's a great thing, but in the US we'll mostly use electric cars.

Bikes have bad aerodynamics: motor bikes have very poor economy given their size and weight. Bicycles are only more efficient because of their low speed. An electric bike might use only 10wh/mile, but that's at 5-15 miles per hour. Bikes have terrible aerodynamics (though not a big cross-section), so an input of 50Wh/mile will be needed to allow you to move close to the normal cruising speed for a Prius (if you're that kind of risk taker).

OTOH, a Prius at 10MPH might well use about 1 HP, or 750W, or 75Wh/mile (and less than 20Wh/pax-mile, with 4 passengers), while a bike would need about 50W. Does that make much difference? An EV would only use about 2,400 KWH's per year. That's the electricity supplied forever by .9 KW of wind capacity, which would cost about $1,800. One-time. That's not much.

But are people buying cars of any kind now?

Construction is down to 500K homes per year, vs 10M light vehicles. We'll replace vehicles 10-20x faster.

Isn't the average turn over time for the whole existing fleet of cars is about 17 years?

Until recently, cars less than 6 years old accounted for 50% of miles driven. New car sales have fallen less (-40%) than new homes (-60%).

Shouldn't we educate folks and pushing for policies that get more and more people out of their cars?

A good idea, but most people don't commute long distances because they're in love with their car: that's the only way they can find affordable housing.

Public transport is important, but slow to build. Buses can be bought quickly, but they use as much oil as the average car per passenger. They use more than a Prius, and 4x as much as a carpooling Prius. Rail is much better, because it can be electrified and because it supports Transit Oriented Development but it's slow to build. We need fast solutions for the majority of the problem.

Aren't we moving to a new paradigm of localization?

We're moving to renewably powered electricity. That will work quite well, and look a fair amount like life today. If we want to move to a different way of life, we'll have to make an explicit and separate decision to do so: PO and CC won't force the decision.


joined to vote said...

Hi Nick

Dropped by following the comments on TOD re: Lithium.

Re: walking and cycling - would just like to flag up the travel behaviour evidence from Sustrans and Social Data:


and to point to Holland/Germany Denmark/England(!) for examples of what is possible for walking and cycling:





All are well worth a read and if you add in public health arguments to the benefits they are huge - see report "be active be healthy" at this link (app1 has £values):


The infrastructure side of cycling should be put in context - 1mile of new trunk road is approx £30m. Cycling England's "Cycle Towns" budget is £100m total!:


And in urban areas a lot can be done to make the roads more cycle friendly. Check out the CTCs views here:


So, in answer to your question re: prioritising walking, biking and pt - yes!!


Nick G said...

Good thoughts. I agree, we should encourage all of these things.

Please note that your sources are all European, and that Europe has very different infrastructure than the US.

I wish I had more room for titles, for what I really want to ask is: should these be considered more important than electrification of light vehicles (cars, etc.)? The answer to that is no.

I'll try to edit my post to better reflect that.

joined to vote said...

Hi Nick

I don't have much US data but these guys kow there stuff and I'd suggest having a look before making your mind up:


Their analysis is that half the trips in America can be completed in a 20min bike ride.

The only US cycling experience I have is touring New York a few years back by folding bike and I found the City a breeze compared to London. Flat with a grid layout and less hostile traffic. That gives 8million people access to a pretty good cycling and walking network - just reduce the traffic a levels a bit and your in business.

Re: electrification - electric bikes are really doing well now. There is no need to haul a ton or more of car around for single person urban journeys. Check out Extra Energy for more info:


Yes European but I'm sure you can pick up some good info and leads to US sources.