Wednesday, July 02, 2008

Commuting Cost Arithmetic

If the price of gas remains at $5 a gallon or higher, will people move back to Center Cities? Many bloggers seem to be assuming that people work in the Center City and live in the suburbs . This is a 1950s view of suburbia. Ed Glaeser and I have written about this point extensively. Haven't you read this and this ?

When people work in the suburbs, will they save many gallons of gasoline if they move to the center city? Yes, they will be closer to their center city friends and stores but they will still need to reverse commute by car to their jobs (unless they can ride the Google Bus from Center City San Fran to Mountainview).

So this raises the question of whether high gas prices will push employers to move back to the center city? Employers who need land (think of Google) will be unlikely to want to rent out 35 stories of a skyscrapper.

High gas prices are likely to LOWER gas prices at the suburban fringe making it more desirable location for firms seeking to cost minimize. As such land is less desirable as suburban housing, firms will seek it out and their employees will locate nearby with a short commute from their suburban house.

Is $5 gas a significant commute cost? This depends on your wage. Consider the following deep math;

Suppose you own a vehicle that gets 25 miles per gallon and you work 25 miles from where you work. Suppose you drive at 25 miles per hour.

Then to get to work, you need to purchase 1 gallon of gas and use 1 hour of your time.


Total One Way commute cost = price of a gallon of gas + hourly wage


Case #1: you make minimum wage = 5 + 7 = 12 and the share of expenditure on gas = 5/12

Case #2: Ivy League graduate = 5 + 100 = 105 and the share of expenditure on gas = 5/105

So this simple example highlights how the wage can swamp the price of gas for the high skilled but for the less educated, gas is a huge part of the commute cost.

4 comments :

Andrew said...

I assume this is supposed to read "High gas prices are likely to LOWER _land_ prices at the suburban fringe..." and not 'gas prices' as is written. But then I don't understand this stuff very well.

Ironman said...

Very nice point regarding the gas price/wage relationship - Felix Salmon only touched on it in his post considering the math for whether moving closer to work might make sense in reducing one's commuting costs (tool here), but it's a hugely important consideration.

el duderino said...

I don't quite follow your reasoning. I believe you're saying that high gas prices will indeed bring employees closer to their places of employment. If that's true, than we'll undoubtedly see higher densities in urban areas.

Sure, "urban area" has a slightly different connotation than in the 50s. In other words, what we once considered suburban is now urban and what we once considered rural is now suburban or exurban.

Either way, we'll see higher density levels surrounding commercial cores, correct? And those commercial cores are more dense in SF or Seattle than they are in Mountain View or Redmond.

Nolan said...

El duderino is correct, nobody is saying we'll all move to center cities. MANY will, because center cities are in every case the single largest hub of job activity. That said, they rarely encompass the majority of jobs, so we will see suburban town centers and office parks emerge as centers. They were in the past and will be again. People will live close to their job, but they will also, where possible, live close to transit. Rarely will two-income households be able to locate near both jobs.

Finally, as someone with an Ivy League degree. I assure you that $100/hour is not median income for that group, and your example is a red herring anyway. There are many, many more people making between $7-30/hour than $70-100. Not comparable whatsoever. If $5-7 gas only affects people for whom the price/wage relationship is 5/30 or higher, it will be enough to radically change the landscape.