Income by Subway Station

In April, the New Yorker ran a piece about income inequality along each of the subway lines, in which they made an interactive graphic portraying the median household income (from census data) at each of the subway stops on the line selected. For example, this is their graph for the F line.

It is an interesting exercise and produces some potentially informative graphics.  However, in determining household income, the New Yorker used a... I'll be polite: "unusual" technique.  They simply used the income value for the census tract in which their coordinates for the subway station lay.  This results in a number of problems.

Census tracts must be between 1,200 and 8,000 people, and most in New York seem to be mostly in the 2,000 to 5,000 range.  They vary in size as population density changes, but in New York are generally 1/16 to 1/4 square mile -- on the order of 8 blocks.  Many of the subway stations, like Columbus Circle or Carroll St have entrances 3 blocks apart from each other and in two different districts.  This means that the New Yorker's analysis would produce different income values based simply on which stairway they chose to mark the station.  The amazing thing is that they celebrate these statistical artifacts:

$142,265—The largest gap in median household income between two consecutive subway stations on the same line (between Fulton Street and Chambers Street on the A and the C lines, in Lower Manhattan).

As a first correction, we should at least average all of the census tracts that actually have subway stairs in them.  But what about other nearby ones?  How far out should we go?  Should neighboring tracts count in our average the same amount as slightly more distant ones?

In my analysis (you can argue with me if you want), I created a linearly decaying income weighting function, out to 1/2 mile (2.5 avenues or 10 blocks in Manhattan).  What this means is that tracts with a center on top of a given station get full weight, those 1/4 mile away get half weight, and those 1/2 mile or more have no influence.  It is important to note that the weighting values in the average for the tracts are relative to the values for all other tracts for a given station.  So for example, if a station is surrounded by 6 tracts, all with centers 1/4 mile away, all 6 would count equally towards the station's average income.  If there's two at 1/4 mile and two at 3/4 mile, the closer ones will influence the average by three times as much as the farther ones.

Thus, I get a map with the following median incomes. I have not created a line-by-line graphic like the New Yorker, but the data's all there if someone wants to be clever (see borough names below).


You can also explore a full screen version of the map.

The first thing you'll notice is that the income along the lines is much smoother in this analysis. The Fulton-Chambers difference is now $50,000, not $142,000.  The really big differences that remain are for stops actually separated by large distances.  The 4 largest (I believe) are the 4/5's 86th-125th St difference of over $100,00; The 2/3's Chambers-14th of $65,000; the A/D's Columbus-125th of $65,000; and the F's York-E.B'way of almost $60,000 across the East River. The greatest change for stops that are actually near each other is on the Upper East Side, when the income drops from $158k-$133k-$91k-$43k-$29k on 77th-86th-96th-103rd-116th Streets.  And poor Sutter Avenue on the L remains $12,000 less than any of its neighbors or anywhere in Brooklyn.

Since this technique involved comparing the distance between every station to every census tract (using data from the American Fact Finder), I broke the analysis down by borough to avoid creating a truly gigantic matrix.  For Manhattan and the Bronx, this is fine because no one walks across the East or Harlem Rivers to catch a train.  In Brooklyn and Queens, there may be some loss of accuracy along the border, since for example, no Brooklyn tracts are counted in the Seneca Ave M station, but there are few stations where this could really have an impact, and the data do not seem unusual.

I will not claim that this is the best way to analyze.  Maybe I should have a larger or smaller decay distance than 1/2 mile.  Maybe I should have used a different decay function than linear.  Maybe no decay function at all and simply give every tract with centers within 1/2 mile of the station full weight.  Maybe I should have even divided the map up into Voronoi polygons with one station in each and assign each census tract to exactly one subway stop.  But at any rate, this analysis produces more realistic and informative result than the technique used by the New Yorker.

96% of U.S. transportation powered by petroleum

With all the talk of alternative fuels, it sometimes helps to put a sense of scale on things. The growing prevalence of electric cars is one rational for basing the federal highway taxes to vehicle miles traveled rather than gas consumption (more on this in a coming post). In 20 years, some predict electric cars will make up 64% new sales, but in the near term this is not the case. Even if the experts are right and there are 3/4 million electric cars on the within five years, there are currently more than 137 million licensed passenger cars in the U.S.

This double pie chart depicts what fuels transportation in America (data from The Geography of Urban Transportation, p 278). No details like passenger miles or ton equivalents, but simply trillions of BTUs (the sum of all is 27,500). Gasoline and diesel together make up more than 3/4 of the total. Jet fuel and ship fuel are much smaller but not insubstantial shares. (I'm not sure how they count international journals; another paper I saw took all the usage for domestic trips and half for international.) Our running total is up to 96.4% thus far.

Now we get to the final 3.6% that is not derived from petroleum. By far the largest chunk of this -- 2/3 of the remainder -- is another fossil fuel: natural gas. Oh, like those dual-fuel cars and delivery trucks in those articles, you think. But no, this natural gas is burned to power pumps which push more natural gas through pipelines. (It's still transportation energy, even if there's no vehicle involved.) Another quarter of the small pie is electricity used for the same purpose. Lastly, the final sixth of the little pie, or 0.29% of all transportation energy, is used in non-petroleum vehicles that actually move, like we normally think of for transportation. Of this, almost nine-tenths is electricity for subways, commuter railroads, the electrified portions of Amtrak, and a couple electric trolley buses. The rest is for natural gas buses. For perspective, this total of .29% is less than the gasoline used by recreational boats.

What about the electric cars? Well, the table only goes down to the tenth of a trillion BTUs, and the electric cars just get lost in the rounding. The other news-maker, methanol, is similarly zero. Interestingly, this doesn't imply that biofuel is insignificant. The gasoline fraction includes Gasohol, or 10% ethanol. From an FHA report, it seems that 13% of all gasoline sales are from Gasohol [Table 8 ÷ (Table 2 Sum × 365)]. This means that ethanol usage accounts for three times the energy as all other non-petroleum sources for vehicles (not counting the pipelines).

Taxi Ride-sharing to Expand in NYC

The New York Times has an article about new taxi sharing in midtown New York. Along 3 cross-town routes that are not serviced by a subway ride without a transfer, "up to four passengers will be able to share a yellow taxi ride, car-pool style. The flat fare will be $3 or $4 a head, significantly less than the regular metered rates, and riders can ask to be dropped off at most points along the route." (The current taxi fare is $3 plus $2/mile.)

This seems like it's good for the riders (they pay less), for the environment (more people traveling in each vehicle), and the cab drivers (larger total fare). However, since it's decreasing the demand for taxicab trips, some cabbies are complaining:

“Every additional passenger that gets into one cab, that means a second cab is left empty,” said Bhairavi Desai, executive director of the New York Taxi Workers Alliance. “It’s horrible to implement a program like this in such hard economic times.”

While it's arguably bad for some drivers, it is very good for passengers, so the second argument doesn't make a lot of sense (except that in general, midtown taxi riders earn more money than taxi drivers).

What is interesting about this new plan is that the fare is not particularly higher than the $2.25 single ride on buses or subways operated by the MTA. So if there's such demand, I'd think the MTA could start running 8-to-13-passenger vans along these routes just charge the $2.25 base fare. Once you start adding more people to the vehicle, all the starting and stopping starts to add delays, but I bet most people are just going the full distance anyway so they could eliminate the midway stops.

Personal Carbon Trading

Yesterday I saw Yael Parag from Oxford University present on a plan the UK is looking at for "personal carbon trading" (Oxford description here). The UK, like lots of cities and countries, has all these grand plans for 30% reduction in Greenhouse gases by 2030 and 80% by 2050, but no real plans to accomplish this, and minimal progress. This cap-and-trade type of idea might be able to accomplish the goals. Here is how I understand the plan from the talk:

The UK is generating some amount CO2 each year. Of this, 40% is directly used by individuals in the form of non-business transportation, home heating, and home electricity. The rest is used by commerce, industry, and agriculture for similar purposes, plus manufacturing.

The presenter mentioned, though I can't find any reference of this on the website, that the 60% would be auctioned out to all non-individual users.

More interestingly, the 40% would be distributed evenly among all people. Each person would then have some monthly (or yearly) balance of Carbon. Whenever people buy things that actually produce CO2 when used, they enter their Carbon card number, and their account is debited. An important point is that there wouldn't be that many of these transaction, since the only things counted would be

• Gasoline/diesel
• Monthly heating bill (gas/oil)
• Monthly electric bill
• Air travel

The carbon credits could of course be bought and sold, and I bet eBay would just be the beginning. I can see entire companies emerging to manage, loan, invest, and speculate on credits.

Although Fat Knowledge prefers taxes to permits (and in general I do too), there are a few points that speak in favor of CO2 credits.

• Energy is a fairly inelastic commodity: that is, the demand is not especially affected by price. In summer 2008, gas prices rose something like 75% from the previous year, but vehicle miles traveled dropped just 5-10%.
  
• People respond to social norms. Just like the California electricity users who cut back consumption to be closer to that of their neighbors, Britons may alter their behavior to use closer to what the average citizen uses, for social norm reasons as well as economic.
• Caps are good for controlling things that should be, well, capped. Taxes are good for things that the government wants to discourage, but doesn't care if a specific amount are used. For instance, the high cigarette tax (in theory) reduces demand, but it doesn't limit the number sold. But if scientists say that the amount of CO2 generation shouldn't increase, it is difficult to estimate what tax level will accomplish this, whereas the cap dictates the amount and lets the demand set the price. And the amount of credits could slowly be ratcheted down to meet that level that the government/scientists believe is sustainable.
  

The system has the potential to work well. One concern I had was that people would chalk up all the driving they could as "business travel". But if the firms have to bid on carbon pounds, they might not want their employees using them up. And since many of the poor do not drive cars and live in smaller houses/apartments with smaller utility bills, they could earn extra income selling credits, making this a Progressive measure.

Nevertheless, I do have a few things I wonder about.

• If firms bid on credits, why is air travel counted for personal consumption? Wouldn't that count twice? Or maybe the system is set up so that the airline industry can pass on the credit use to consumers, rather than the cost of auctioned credits.
  
• Mass transit is not included (initially) to encourage use rather than cars, and because there is in general far more of these transactions a month, so it would be a pain to have to debit the carbon card every time. Would intercity buses and rail also be exempt, or would they pass on credit consumption like airlines?
• For electricity, would we use the average CO2/kwh of the entire country, or the local company's portfolio? Would (in the US) hydro-happy Washington's electricity not debit much, but a lot of points would come out for a kWh in King Coal states like Kentucky and West Virginia? And if, as you can do, you pay a premium to guarantee that your electric company buys at least your amount of kWh from Wind or whatever, would that make your electricity free of credits?
  
• Should credit allowance be based on the household? Or is the individual better? How should children be counted? Should you be able to merge accounts, so one family member isn't stuck somewhere unable to buy gas while the other has a surplus? And how much would this complicate divorces? (No, those carbon credits should go to me!)

The government still gets some revenue from the non-residential credits permit sales. But this would certainly be much more complicated than a tax. And would people trust the big bad government to have so much control of people? Would it be better if the system was administered by a big bad corporation? Any thoughts?

Mass Transit fights to protect its information...

...from people making applications that would improve use of and increase ridership on trains.

Schedule Use
Second Avenue Sagas writes about how the MTA, New York City's mass transit authority, has been trying to force/scare people away from making unaffiliated applications. For instance, Chris Schoenfield "wrote an application with the Metro-North schedule data." However, the MTA

ordered him to cease selling the iPhone application. This charge rested on the claim that the MTA owns the copyright to the schedule data and that Schoenfeld’s use of the data violates that copyright.

Unfortunately for the MTA, the charge

has no basis in legal reality. As the Supreme Court held in the seminal case Feist Publications v. Rural Telephone Service, 499 U.S. 340 (1991), pure facts are not copyrightable, and train schedules have long fallen under this rubric of pure fact. The MTA can claim a copyright on the presentation of its train schedules, but the train schedule information itself falls under Feist.

I thought I had read (perhaps on Fat Knowledge?) about the Frankfurt train system (or some other German city) doing the same type of thing, but I can't find that story anywhere.

Use of Images

The MTA could come after me for putting this 7 in a purple circle on my blog without their permission. And it wouldn't even matter if I changed the color to green: judging by the case of a guy in San Francisco trying to poke fun at his own city's mass transit system, the MTA seems to think they own the rights to every letter contained in any color circle. Nevermind that (according to Wikipedia's legal department anyway) "text in a general typeface and simple geometric shapes are not protected by copyright."

There may be hope. The New York City Council has written a letter to the MTA urging them to open their scheduling data for application developers, and the Muni T-shirts are back on sale, but this is one big Copyfraud put on by the MTA.

Cash for Clunkers

One of the most talked about "green initiatives" passed so far this year has been the Cash for Clunkers program, aimed at getting people to trade in their old gas-guzzlers for more fuel efficient cars. There has been a lot of bashing that the efficiency-improvement requirements to get the cash incentive are too modest (22 mpg min. for new car, 4 mpg improvement for $3500 rebate, 10 mpg for $4500). However, according to the Freakonomics Blog, most people are upgrading more than the minimum.

The average vehicle being traded in gets about 15.8 miles per gallon (6.33 gallons per hundred miles), and the average new vehicle that replaces it gets about 25.4 m.p.g. (3.94 gallons/100 miles).

There is substantial fuel saving in this. As Fat Knowledge has pointed out (and Edward Glaeser agrees),

The jump from 10 to 20 m.p.g., for example, saves more gas than the one from 20 to 40 m.p.g. The move from 10 to 11 m.p.g. can save nearly as much as the leap from 33 to 50 m.p.g.

Mr Glaeser goes on to say that this is better than high-speed rail because the savings start immediately. But it reinforces our car dependent way of life. And as the Wall Street Journal points out, it's really expensive.

In a nutshell, getting older cars off the road and substituting them with more fuel-efficient models appears to cost about $365 for each ton of carbon-dioxide emissions that are saved. ... The government estimates of the cost of carbon emissions ... are in the neighborhood of $28 a ton. So, Mr. Knittel asks, could the program ever actually be cost-effective, environmentally-speaking? Sure—if all the clunkers had stayed on the road, racking up mileage and emissions year after year for 60 years each, then it actually makes sense.

Buying more fuel-efficient cars does "save money" for the drivers, but the bill only benefits people who can afford to drive. Since in general, people that drive to work are wealthier than those who take public transit, the Cash for Clunkers program, in general, does not help the people that need it most. One even greener rider for the bill that would help the less wealthy would be to allow the $4500 credit to be used for mass transit passes.