When I was learning how to drive many years ago, my dad gave me a tip to help me keep from getting lost: East-west freeways/highways are indicated by even numbers and north-south by odd numbers. I was listening to the traffic report this morning, and I realized that the 905 runs east-west. Tell me, has Dad led me astray?
-- Jessica McCloskey, the net
Check the copyright date on that volume of The Gospel According to Dad. By now we should subtitle it Wit and Wisdom that Used to Be Sort of True, but Is Becoming Less True as Things Change and Life Gets More Complicated and Annoying. And this answer sure is complicated and annoying. Dad, of course, was trying to be his usual helpful self. Not likely he wanted you to tootle off for a day in Dulzura and accidentally end up in Eureka. As a general rule, route numbers do run the way he said. But there are enough exceptions to make it worthwhile to pack a map.
California highway numbers are assigned by consensus of three groups: Caltrans, the California Transportation Commission, and the legislature (in coordination with the feds, of course). That alone could explain any confusing designations. They christened 905 back in 1987. At the moment, it's considered an expressway, since there is business access from the eastern section of the road. That will change when the no-access freeway is completed just to the south and Otay Mesa Road goes back to being just a plain old local road. It is also part of a larger scheme, a metro loop linking I-5, 56, and 125 that routes through traffic around the city.
But wait! There's more! According to Caltrans, 905 has been numbered as a spur route-- an offshoot of I-5. According to DOT rules and regs, as a spur its designation should be three digits, beginning with an odd number and ending with the number of the route that it is a spur of. (Fuzzy grammar, clear explanation, I hope.) We could also make the argument that 905 does run north-south. North-south-ish, anyway. It's clearly north-south at the border crossing, and maybe north-south at its west end, with a vague sort of north-south trend in the middle. Anyway, that's how the committees saw it, since route numbering seems as much art as science. Why the number 9 was chosen as the first digit, well, could be that it was the only digit available. Or that 905 made a neat, easy-to-remember number since the road also links to 805. By the way, 805 is what's known as a bypass route; it starts at I-5 and ends at I-5. Bypass routes begin with even numbers and end with the number of the route it bypasses. Caltrans swears the system is supposed to help drivers, not confuse them. And they also swear that the odd-north-south/even-east-west business is their ultimate goal. They just need to tweak the system occasionally. Route 905 is a big tweak. And a tweak by committee. Logic didn�t stand a chance.