MARTA expansion versus the dream of self-driving cars

MARTA riders waiting for trains at Five Points Station in the morning

Expansion of MARTA rail, funded through a potential new tax in Fulton & Dekalb Counties, is big news right now. An AJC writer weighs in on the the issue this week in a column that sees him dismissing MARTA expansion. Why? Because he thinks the system is “underused” where it already exists. Also, he thinks mass transit will be useless given that robot cars are coming in a few years.

Underused? Let’s look at how MARTA ridership stacks up. Let’s compare it with a larger system: DC’s Metro.

MARTA annual ridership (all modes): 134 million
— 38 rail stations
— 47 miles of track

DC Metro annual ridership (all modes): 209 million
— 91 rail stations
— 117 miles of track

MARTA has less than half the rail miles and less than half the number of stations as DC Metro. But it has well over half the annual ridership (that’s a total of bus & rail). That’s significant.

And this claim that self-driving cars will make transit useless in a few years is a head scratcher. Let’s think about that.

How many commuters fit in a single self-driving car? One or two maybe? Whereas a train car or a bus can carry a lot of people. I didn’t bother to look up the exact number. It’s a butt load, approximately.

How much space does a bus with 40 people take up on the road? Exactly one bus length, in one lane. And how much road space is needed by 40 cars with maybe a single commuter each? A lot more (see image below).

This space efficiency is key for growing cities. Self-driving cars take up this same amount of space on roads.

And is population expected to go up or down in coming years? Up. Over three million more people will live in the Atlanta region by 2040 according to current projections. What will a 20 mile commute look like in a sea of robot cars, with that added population, and with no rail expansion? I hope we don’t find out.

There’s an excellent recent writeup on the subject of self-driving cars that I recommend reading. It urges us to be realistic about what this technology can achieve:
http://www.canberratimes.com.au/…/we-need-to-stay-realistic…

Self-driving cars could be a very useful part of our range of shared-car services including things like Uber, ZipCar and taxis — there’s no doubt about that. The technology is incredible and it will have an important role to play in mobility for some people. But mass transportation, in the form of trains and buses, is extraordinarily efficient in the way it moves large groups of people around. In big cities with growing populations, efficiency matters.

Here’s a photo I took from my morning train as we sailed over the highway, filled with solo commuters in cars. Self-driving or not, the single-occupant cars can only accomplish so much in comparison to a train full of commuters.