February 18th, 2012


This Isn't Really Working For Me - 4: Highway 102 (and sequential exit numbering)

Most of these images are screen captures from Google Maps in Street View. You can go amazingly far in Street View and it's easy to waste spend hours tracking down unique interchanges and remote border crossings.

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I'm passionate about this subject, so I've gone on at length. If I can only leave you with one takeaway, let it be that sequential exit numbering (at least on roads more than a few kilometres in length) is a bad idea. A much better alternative is to number the exits according to the kilometre posts. British Columbia, Alberta, Manitoba, Ontario, Québec, and New Brunswick are already doing this. The only significant holdouts are 1) Nova Scotia and 2) Newfoundland and Labrador (surprising, as their implementation of exit numbering occurred fairly recently).

Numbering according to kilometre posts has at least two big advantages:

1. Expandability – If you should ever build a new interchange, there’s no need to worry about an appropriate number to assign. You also avoid most A-B-C-D messes and can save the letters for compass directions at the same interchange and certain other situations.

2. Understandability – If you just drove past Exit 14 and your destination is off Exit 28, you know that you have 14 kilometres to go until your exit is reached. Better yet, with the kilometre posts that we have, you can easily track the distance while you’re between distant exits.

I admit at least one disadvantage: it’s going to mess you up if you’re accustomed to counting the junctions as you go by them (does anyone do this?), but even then that system is already broken by our haphazard implementation of sequential exit numbering.

Please Nova Scotia, let’s do something, before we face a tragedy like an Exit 5½.

Finally, if Nova Scotia’s Highway 102 isn’t enough to convince you of the folly of sequence-based numbering, let’s take a quick <ahem> gander at Newfoundland and Labrador Route 1:

Off the boat in Port aux Basques, you come to a sign that looks like an exit gore – you know, it has the word “EXIT” in it – but it’s really just pointing the way to Highway 470. But anyone who doesn’t know Newfoundland roads (including many of the people driving their RVs off the MV Sleepy Trucker) is going to think that’s an exit number. Anyway, this has nothing to do with sequence except that you should pretend this is signed “Exit 1”.

Now, 144 kilometres later, outside Stephenville, we come to Exit 2. Yes, they have sequential numbering on a 900+km road. I’m sorry, Newfoundland, that we in Nova Scotia were such a bad influence in this case. Sorry.