Dear David,

You might have noticed recently that I’ve started to get into the office a bit later than everyone else. Only a little bit later, of course — ten, fifteen minutes tops! I know this is a bit out of character, but it comes down to this: my morning bus ride is taking a lot longer.

As you know, I live in Sydney’s north-western suburbs, where’s it’s still possible for a single-income family to rent a three-bedroom semi-detached with space for the kids to play. It’s a good 30km on some pretty heavily-trafficked roads due to decades of non-existent mass transit expenditure (though thankfully the North West Rail Link is still on track for 2019).

Being a good little analyst, I sought out some data to back up my anecdotal experience. Thankfully, the RMS Roads Report provides just that. Here’s the daily average speed of traffic heading east on the M2 between Pennant Hills Road and the Lane Cove Tunnel (10.6km), during the morning peak (6:15–9am):

The graph above shows that my normally predictable morning commute has become much more variable since August. While it might not look like a huge change — an average of about 13km/h over 10km, or a few minutes slower — remember that this graph includes the 6–7am period when traffic is much lighter.

In November, the average traffic speed has regularly dropped within spitting distance of that crappy Monday morning after the June long weekend.

While the RMS data is good, you can’t compare a road’s (inbound) morning and (outbound) afternoon peaks, and you can’t see whether certain days of the week are affected. So I dug into the RMS API and grabbed history as far back as it exists: September last year. (Here’s the very basic and hacky code I’m using to grab the data. Hey, I’m an analyst, not a developer.)

(Aside: It would be really nice to see RMS open up historical traffic data as part of its Transport Data Exchange program. They do have predicted travel times for the M1/M2/M4/M7 but nothing historical. Also while we’re on the topic: open up the realtime public transport data feeds, guys!)

The next set of graphs were built with Tableau Public and you can find interactive versions here or at the links beside each one. Additionally, the full CSV data set is available at this link (note weekends aren’t measured).

OK, so here’s the actual average speed for every weekday morning and afternoon peak period since September last year on that stretch of road:

Average speeds during AM & PM peak periods

As you can see, mornings used to be pretty predictable but afternoons have been all over the shop (and slower) for a long time. My diary tells me I described traffic on the morning of September 10th as ‘abysmal’, by the way.

Another way to look at it is by graphing the average of the most recent ten trips. Below, each data point is the average of itself and the nine days previous. It represents how slow or fast your last two weeks of bus trips feel, while smoothing out any terrible days:

I’m really looking forward to those bus rides home during the Christmas school holidays. My commute home has been getting longer on average all year. And what is interesting is that the average AM speed for the week of 28 July is the highest from then to now, and that the PM speed dropped off a cliff around the same time. Despite a brief October recovery, things have gotten worse ever since August.

Now that we have some overlap between equivalent 2013/14 periods, we can see that travel times are universally higher this year (blue) than last (red):

And every day of the week has gotten steadily slower, not just certain days. In the graph below, you can see that average travel time in both AM and PM peaks has been steadily increasing, as indicated by the sloping lines. Check out Thursday and Friday afternoons in particular:

I really wish I had some explanation for the congestion. Perhaps it simply comes down to higher traffic volumes, but that just raises the question of what’s driving that volume up. I don’t have enough data to even speculate.

So how does this affect me?

I’ve been catching the 7:40am bus every day. I used to get off the bus at the first stop in the city at 8:30 and walk the 2km to work in the morning. But recently this hasn’t been an option as I’m arriving in the city at ten to nine or later, and catching connecting buses (thank Opal for free same-mode transfers). This does put a damper on my morning, especially as Sydney has been especially glorious this spring, so apologies for any lack of spirit.

Maybe this means I need to leave home a little earlier in the morning, though with an average 80 minute each way commute, I’m actually spending more time going to and from work than with my two young children on weekdays. But rest assured, this tardiness isn’t indicative of diminishing enthusiasm for the work we do here at Vector 5. I’m really looking forward to the opportunities I’ll have to immerse myself in data in 2015 and beyond.

Speaking of which, I’d better get back to work.

Cheers,

Tim