Thursday, January 6, 2011

Transit and Density

When I first read this Australian article debating the merits of density for transit service, my first thought was to ignore it and not give it the time of day. However, I kept listing in my head all the reasons it was wrong. Obviously I couldn't ignore it, so instead, I'll just refute it.

A study was conducted by two professors from different Australian Universities that say the opposite of what many transit planners have professed to be truth, for quality transit service, there needs to be a higher intensity of land use than what most suburbs offer.

Unless you actually break down the numbers, it seems like they have a point. From the article:

"Their study - which is part of a collection being prepared for the Council of Australian Governments on the dangers of relying on diminishing supplies of oil - finds that cities with densities comparable with Melbourne and Sydney, such as Toronto, Ottawa and greater New York, have better public transport than Australia's two biggest cities.
While greater New York, not just the skyscraper-dominated Manhattan, has 20.5 people to the hectare, Sydney has 20.4 people.
Melbourne, with 15.7 people to the hectare, has only slightly lower density than Ottawa, with 17.2 people.


Dr Mees said higher densities did not always mean better mass transit, citing the relatively low rail and bus use in Los Angeles, even though it is the most densely populated city in the United States.
''There is no doubt that a compact and connected urban form enhances the potential for oil-free mobility through walking, cycling, and greater public transport use,'' the authors write.
''However, we … argue that it is not necessary to intensify land-use across the whole city before significant improvement in both patronage and economic efficiency of public transport becomes possible.'''

My preferred measure of density is people per square mile. Converting their measure of density for New York, 20.5 people per hectare to mine, I get 5,309.5 ppsm. But wait, New York City has 26,000 ppsm. It then becomes apparent that they used regional averages, not city. There is a big difference between New York City and Greater New York. By using that term, they have really missed the mark on what drives New York's ridership.

So why is that important? Because most planners don't encourage uniform density across the region, but rather strategic density where it can be supported. These include places like downtown, stations along a rail line or infill development in the existing urban fabric.

Using the New York regional density averages does a disservice to New York, since City proper has a much higher density than the region. Going even further in, Manhattan has a whooping 66,000 ppsm. Los Angeles, meanwhile, sits between 7,000 and 8,000 across the board. There is very little spike. That makes a big difference in transit ridership. Just the suburban rail lines in New York have 1,000,000 trips a day. That is almost purely trips into the city from the suburbs, regardless of the density outside the central city.

Now notice that small fact. New York's commercial density is a driver of that. The subway system delivers near 8,000,000 daily trips. That is in part because of the high commercial AND residential density. You can literally walk out the door and within a block be at the transit station get to your destination, with a transfer or two, and walk out of the station and be within a block of your destination. That is when transit works best.

You will find that greater than 90% of all "greater New York" transit trips somehow involve the actually city, the densest portion of greater New York. Does Sidney or Melbourne have such a dense area?  No, therefore, it is no surprise that New York has more trips than those two cities. If their urban core developed as densely, you'd surely see a rise in transit use.

Meanwhile, L.A. despite its denseness the authors cite has no such spike anywhere in the urban area. That means a very dispersed, but also much smaller customer base. Those are two bad combos to effective transit service.

Let's be clear here, density is an important factor but it is not the only and perhaps not the most important. As the authors point out,

"The keys to increasing public transport use in outer suburbs are more frequent buses, running at least every 10-15 minutes, and not just in peak hour; better co-ordination with rail services; more convenient transfers; and fares that allow free transfers between modes."

Yes, these are all factors that play a part, but it competely ignores the land use equation.

Here's an extreme example. I build a house in the middle of nowhere and connect it to a transit network and the workplace. I then build an apartment complex else where in the middle of nowhere and do the same thing. Which will produce more riders, the house or the complex? Obviously, the house, so it may not be simply density doesn't matter, but that there is a threshold. The authors ignore that point.

They also ignore urban design principles. An apartment with 200 units built adjacent to a rail station with ample, convenient connections will have more riders than one with 400 units in a gated community that requires you to walk half-way around the complex to get to the station all the while walking along a 6 lane high speed road (I can think of three like this next to Dallas rail stations).

The authors "solutions" are entirely supply side. They do little to increase the demand for transit service. If land use and density aren't compatible with the types of solutions they are suggesting, it won't work financially. Now if money isn't an issue (yea right, I know), then you can run the types of service they are suggesting to stereotypical suburbs.

They also ignore other factors that effect transit use, such as car pricing, parking strategies, walkability, station and stop locations, etc. If an area improves in these areas toward a more transit-friendly approach, they will see a rise in transit use, regardless of density levels.

I think this is a great example of the need for the peer-reviewed journal. Though I know nothing of the Australian Planner Journal, I know you'd never see this type of thing in the Journal of the American Planning Association.

It is also a great example of the need for planners, but also the easy mistakes they can make (and have made). The saying a jack of all trades is a master of none could easily be applied to planners. Of course, politics can come along and muddy the waters completely, rendering everything else a moot point.

No comments: