Late-Night T Service

(EDITOR'S NOTE: post updated on 9/30/14 due to an unaccounted for mismatch in taxi and MBTA data set time-ranges. My first retraction. I'm sorry.)

Earlier this year on March 28, Boston finally caught up with the rest of the large cities of the world and offered late night subway and bus service on Friday/Saturday nights. More interestingly, as part of the Late Night T data challenge, the MBTA released over a year of their aggregated ridership data: number of transactions per 15 minute period by date, hour, line, stop, and day of week. In addition, as part of the challenge MassDOT released similar data on taxi pickups and dropoffs, complete with latitude/longitude!

The released data only covers the hours of 10pm to 3am, and only Friday/Saturday nights, but it is still an interesting data set that we can learn from. The whole data set can be found on GitHub.

I missed the time window to participate in the actual hackathon, but I still want to explore the data. How has late-night T service manifested, and how has it affected the taxi business? In this first part of what will certainly be several analyses, I'm going to focus on aggregate ridership. Future posts will cover more detailed changes across neighborhood/geographic position.

A note: late night MBTA service started on March 28 2014, and the data sets released have a common period of March 1 2013 through May 31 2014, so I am confining all of this analysis to the range March 28 - May 31 across both years to control for seasonal effects (especially important with all of the outdoor patios down on the waterfront).

Total Late-Night MBTA Ridership by Station

These are the top 25 lines by total transactions at fare gates during the aforementioned March 28 - May 31 time period. There are five main areas these stations serve, all with vibrant nightlife scenes: Downtown Boston (near the Common and Faneuil hall), Downtown near the waterfront, Back Bay, Cambridge, and near Fenway. The student factor is also important, with Harvard Square, Kendall Square (MIT), and so much of the Green line (covering BU and BC) showing up high on the list. But this is just a single total; what we're really interested in is the effects of late night service specifically.

Late-Night MBTA Ridership by Year and Hour

This tells a really clean story: T service is a little up across the board, but with late night ridership you actually see slightly fewer midnight rides as a percentage - people can stay out later now, and they definitely take advantage. Let's call this the midnight effect. I thought we'd see a spike at 1:30 (last-call) or 2:00 (bars close), but the late-night crowd is fairly evenly distributed in time after midnight.

But as you might imagine, Bostonians aren't using all lines equally (or stops, but that will have to wait for another day).

MBTA Ridership By Line and Hour During Late-Night Service

Given that the total late-night ridership was so concentrated on the Red/Green/Orange lines as we saw above, and that those lines have the most obvious explanations for late use (bars and proximity to the neighborhoods of people who stay out late) this isn't that much of a surprise. Red, Green, Orange get the lion's share of late-night usage. There is some late bus service, but given the total ridership numbers it is likely distributed primarily between the 1 Bus (Harvard Square through South End, down Mass Ave) and the 66 (Harvard Square to Brookline and eventually Dudley Square).

Now, let's look at the difference from 2013 for each of these lines. So as not to get the plot too crowded, I am going to split the above plot into (Green, Red, Orange), and (Blue, Bus, Silver).

MBTA Ridership By Year, Line, and Hour

For the popular late-night lines

The Green line in particular has a HUGE midnight effect that stretches back all the way to 11 pm. And the Orange line actually gets a boost in ridership across the board, with no noticeable midnight effect at all.

Red is down a little across the board, before midnight anyways. Where, and why, we will get to in a future post.

For the less used late-night lines

Bus service is definitely up, and there are spikes in late-night usage around 1:00 and 2:00 am. The Blue and Silver lines have some more traffic overall, but just don't serve the late night hotspots that the other lines do, so they're going to go a little neglected in this aggregate look. Blue will likely come up again later in some of the deeper dives.

All-in-all, late night T service seems to be popular. So we'd expect a drop in overall taxi activity after midnight, right?

Total Taxi Pickups by Hour

Whoa. Taxi ridership is actually noticeably down across the board. I actually think this is more of an Uber/Lyft effect, since taxi pickups are down uniformly - if it were the late-night T service, you'd expect the most noticeable change to occur after midnight. But Taxis actually do a little better after midnight in 2014, as a percentage of their total pickups. So more people are out (whether or not this is because of T service) and it seems to be a net gain for the taxi industry - modulo their large overall drop in ridership anyways.

Compared to the overall MBTA ridership from earlier:

As far as where the changes in ridership happened? Tune in next time...