I moved from LA to Boston about a year ago. Since I hate driving, I was looking forward
to moving somewhere with a more effective (read: existing) public
transportation system. At least, I was
looking forward to it until I realized my apartment was situated on one of the
green lines of the T (I recommend the 4th and 9th reviews especially).
For those of you unfamiliar with Boston’s public transit
system, known as “the T”, it consists of the red, blue, and orange lines, all
of which are reasonably timely subways, and then the green line. The green line has four different branches,
most of which operate at street level and, for some reason, lack any sort of
tracking or timing system.
One
day at work, I mentioned my disappointment with the green line to my labmates which
led to a heated debate about which of the four green lines was the worst. I was convinced the B green line was slower
than the C line while my friend, Aishu, adamantly believed that the C line was
slower. One of the senior postdocs, who
had been living in Boston longer than both of us, explained that the quality of
the green line branches decreased alphabetically. The B branch was the best, followed by the C,
then the D, and, finally, the E.
Whenever we walked into a station that served at least the
B, C, and D lines, we noted the time when we got to the platform and the times
at which the trains arrived until the train we were waiting for came into the
station. We also noted the crowdedness
of the train car we were in. I should
point out that because the E line shares fewer stops with the B, C, and D lines
than they do with each other, we do not have much data on the E line. Additionally, most of our data comes from
weekdays between 6:00 and 8:00 pm. It is
also important to note that we did not measure the average waiting time for
inbound trains or how quickly the trains traveled to their destination. Still, we ended up with enough information to
test the Massachusetts Bay Transit Authority’s claims about the average wait
time for green line trains.
The first thing we looked at after our recording our six
months’ worth of data was the frequency of the trains. How many trains would you have to watch go by
before you finally got the one you wanted?
While not necessarily as informative as the actual waiting time, this
factor still has some role in determining how irritating each green line
is. As you wait on the platform, your
hopes rise every time you hear the piercing shriek of a green line train coming
into the station just for it to be the wrong branch. Repeat this experience of having your hopes dashed
several times in a row, even if interval between incorrect trains is just one
minute, and it’s easy to see why train frequency matters.
Our data is summarized in the figure below:
Of course there are fewer instances of trains being the 5th
or 6th train to go by since we stopped recording once we got on the
train we were waiting for. I was also
usually waiting for the B line and recorded data more often so there are more
instances of B line trains while Aishu was usually waiting for the C line. Excluding these results, we also find that
when an outbound D line train arrives in a shared station it is usually the
first train to come by. Of the 35
recorded D trains, 42% were noted to be the first train of a sequence. This is compared with 28% of B line trains
being the first to arrive, and 30% of C line trains. In the majority of outbound trips, it seems you
will only have to wait for one train to go by before the one you want arrives.
But knowing how many trains you’ll have to count before you
can get on one doesn’t tell you much about how long you’ll actually have to
wait. To determine that, we present the
following data:
 |
| Note: The 12 and 14 minute values are excluded due to formatting reasons and because no trains were recorded at those times. |
86% of outbound B trains arrive in five minutes or fewer, as
do 86% of outbound D trains; however, only 59% of outbound C trains will
require you to wait fewer than five minutes.
This is true despite the fact that the single most common waiting time
for a C train is 0 minutes. 1 in 4 times
when you step into a station, a C train will be waiting there for you, but if
you miss it you might have to wait for a while.
The longest wait time recorded was for a C train at 16 minutes, but on
average you’re only going to have to wait for about five minutes (see below).
The average wait times for the other trains are shown in the
following figure:
We have averages of slightly over three minutes for the B
line and slightly under three minutes for the D line. The E line appears to be on par with the C
line, at around 4.5 minutes, but keep in mind we only recorded seven points of
data for E line trains so the accuracy of that value is not without error.
According to the MBTA, B line commuters can expect to wait 10
minutes for a train in the evening (6:30 pm to 8:00 pm), C line commuters –
seven minutes, D line commuters – 10 minutes, and E line commuters – 10
minutes. While the average waiting times
for all the lines are below the MBTA estimates, remember that the MBTA is not
distinguishing between outbound and inbound trains and may list longer than
expected times to be safe. Nevertheless,
it is somewhat reassuring to know that when waiting for an outbound train, you
will probably be on your way in under five minutes. Still I’m sure Bostonians would appreciate it
if real-time updates were made available.
So you’ve waited your average 3.8 minutes, caught your
train, and are on your way home. How
much space will you get to yourself on the ever luxurious green line? To take into account the amount of discomfort
one might have to endure on their commute, Aishu and I came up with a
crowdedness scale. It ranges from 1 –
“spacious”, meaning “Wow, I practically have this train to myself! Actually that’s kind of weird…” to 7 – “too
full to get on” which I expect I don’t need to define. In between we have 2 – “not full and not
empty” indicating that there are a few people sitting, 3 – “full/normal”
meaning the seats are all full and there are some people standing, but there is
enough space to move around, 4 – “crowded”, a level at which you might have to
stand closer to other passengers than desired, but you can still breathe, 5 –
“very crowded” meaning “I’m starting to get ever so slightly
uncomfortable. I really hope nobody
tries to get on at the next stop”, and 6 – “stupidly crowded” at which point
you find yourself thinking “How did more people fit onto this train? If I don’t get out of here soon I’m going to
start biting everybody who’s touching me!”
As we primarily took the B and C trains, we only have
crowdedness data for those two lines.
The results are as follows:
The average crowdedness of both lines were around 3 –
“full/normal” although the C line tended to be slightly less crowded than the B
line. The only recorded instances of a
train being too full to get on to (level 7) were with B line trains. Never fear though, you are likely to find
space on your train on either line.
Overall, it looks as if reality is actually better than what
the MBTA predicts, at least for outbound trains. On average, you will wait for less time than
the MBTA website claims and you’ll have space in your train car, if not a
seat. Counter to our postdoc’s beliefs,
quality of the green line branches doesn’t decrease with alphabetical order, as
shown by the D line’s shortest average waiting time. It is important to note, though, that without
data on how much time you will actually spend on the train, it is still
difficult to conclude whether the green line is worth using. Considering the average speed (4.1 miles in 24:49?) of a green line
train and how small Boston is, might I recommend a bicycle instead?
