LongCommute

Not how the crow flies to get to work each day

by George Taniwaki

I really don’t like to drive to work. I’ll do almost anything to avoid a long commute. For most of my adult life I have either walked or ridden a bus to get to work. Yes, it’s possible. I always chose an apartment to rent or house to buy based on how close it is to my job. And once I’ve found a place to live, I usually reject a new job unless it’s within walking or riding distance. It helps that I like living in big cities.

But I just started a contract assignment in Mountlake Terrace, a suburb of Seattle about 20 miles from where I live as the crow flies (see image above, or not). This isn’t the longest commute in my life, but the first long one in a few decades. And it’s the first long commute where I’m driving alone rather than in a carpool.

Google Maps, initial attempt

The traffic in Seattle is awful. To reduce my commute time, I’ve decided that starting my drive at 6:30 and working from 7:30 to 4:00 will help. Before my first day to the job site, I pull out Google Maps and plot my route (see Fig 1).

CommuteToWorkI405Label

Figure 1. My first route to the office, average 42 minutes every morning

For the analysis in this blog post, I split my drive into segments based on type of driving. Segment A consists of surface streets from my house to the highway. B is 17 miles at highway speed driving north, away from the city, C is a slow slog where I double-back and join the commuters coming into town, and D is the final, short segment of surface streets to the office.

The table below shows details of my commute. Most of it is tolerable. But notice that segment C (the red zone) constitute less than one-sixth of my commute distance but over one-third of my commute time.

Map Description

Dist.

Speed

Elapsed Time

A Surface streets from home to SR520

3

30

6

B SR520 to I-405 to I-5

17

60

17

C I-5 to Mountlake Terrace

4

15

16

D Surface streets from I-5 to office

1

20

3

TOTAL

26

37

42

Google Maps, redux

After a couple weeks of following this route, I’ve learned which lanes to use on which segments to slice a few minutes off my commute. But I think I can still do better. I check Google Maps for some alternatives. This time it gives me a completely different, and unexpected, route. It tells me to go a few miles out of my way south to I-90 and drive north through the city on I-5 (see Fig 2).

I-5 in downtown Seattle is one of the most congested highways in the U.S. I get queasy every time I drive it worrying about getting stuck. But maybe it’s not so bad at 6:45 AM, which is about what time I will get there. So I trust Google Maps and try it.

CommuteToWorkI5Label

Figure 2. Google Maps’ new suggestion, average time 44 minutes

It works. I try the route on two consecutive days. The table below shows the average results. There is congestion on I-5 between I-90 to Olive Way (Segment C red zone) but it is a shorter segment than my previous commute. However, the route is longer, so it doesn’t save much time. Further, I don’t like this route because it limits my options. If there is an accident or other delay, I will be stuck in traffic with no easy way to avoid it.

Map Description

Dist.

Speed

Elapsed Time

A Surface streets from home to I-90

4

30

8

B I-90 to downtown

8

60

8

C I-5 to Olive Way

2

20

6

D I-5 to Mountlake Terrace

14

60

14

E Surface streets from I-5 to office

1

20

3

TOTAL

29

42

39

Waze to the rescue

Waze is a GPS navigation app originally developed in Israel but quickly went global. It uses traditional digital map data and combines it with real-time location data from users including speed, route, reports of traffic jams, accidents, police speed traps, and gasoline prices at nearby stations. Thus, the more people who use it, the more accurate it becomes.

Waze also shows you the current toll price (Seattle uses variable toll pricing) and lets you avoid tolls, ferries, or highways, if desired, when choosing a route.

Google (now Alphabet) acquired Waze in 2013 but it remains a separate entity from Google Maps. Because Waze collects potentially personally identifiable information (PII), it has a less restrictive user agreement than Google Maps and warns users of that fact. (Though most people never read the agreement and just click “I accept”.)

Generating a route is a highly resource intensive calculation that often involves machine learning. To simplify the work, Google Maps generally limits routes to major arterial streets. Waze combines those calculations with the actual routes users are taking to find the minimum travel time. Thus, Waze often creates routes that run through residential neighborhoods. Of course, the neighbors sometimes complain or even fight back by generating fake route data (Wash Post, Jun 2016).

Figure 3 below shows the route Waze recommends for my commute. It looks just like the original route that Google Maps suggested, except for the last segment. I still take the I-5 cloverleaf, but instead of continuing onto I-5, it has me veer right and use side streets to get to the office.

CommuteToWorkI405LocalLabel

Figure 3. My new favorite route to work

Map Description

Dist.

Speed

Elapsed Time

A Surface streets from home to SR520

3

30

6

B SR520 to I-405

17

60

17

C Surface streets from I-405 to office

6

30

12

TOTAL

26

44

35

The best part is that I can see I-5 from the I-405 off-ramp. When traffic is light (speed is 30 mph or more), I can veer to the left and take I-5 to the office. When I-5 is congested, I can veer to the right and take surface streets. While on the surface streets, I can continue to see I-5 and confirm whether I made the right decision and improve my choice for future days.

Waze leads me astraze

With my success with Waze in the morning, I decide to use it for my evening commute home as well. As I turn onto I-5, Waze tells me there is road kill ahead. I wonder where. Then suddenly I see a raccoon and am jolted by the thump. It saddens me to know that I’ve squashed an innocent animal under my tires, even if it is already dead.

The rest of the commute home is uneventful until Waze tells me to exit I-405 at NE 85th St in Kirkland (Fig 4b), 4 miles before my usual exit at SR520 (Fig 4a). Gee, that seems like a bad idea. Should I ignore Waze and keep going straight? Or should I take the exit? Maybe there is an accident on my regular route. Or maybe the crowd of Waze users knows a sneak route. Well, Waze has been pretty accurate so far, so I take the exit.

Ugh, what a mistake. Driving east on NE 85th St takes me straight into a huge traffic jam on Redmond Way. Also, there is a giant construction project on the Microsoft campus, so West Lake Sammamish Pkwy is overflowing with drivers avoiding lane closures on 156th Av NE. My commute today is more than 35 minutes longer than usual. I won’t do that again.

CommuteToHomeI405Label CommuteToHomeI405LocalLabel

Figures 4a, b. My normal commute home, Waze suggestion for 11/21/2019

Conclusion

Both Waze and Google Maps show you unexpected options and are likely to give better routes than you could find on your own. Overall, my experience with Waze was better than Google Maps, but both could use improvements.

* * * *

All this talk about commute time has me remembering a brain teaser from my childhood. Let’s say I want my average commute speed to be 40 mph. One day, I get stuck in traffic and cover the first half of the distance to work at an average speed of 20 mph. How fast do I have to drive on the second half to meet my goal? Hint: The answer is not 60 mph or even 80 mph.