[Talk-us] Freeway directions

Evin Fairchild evindfair at gmail.com
Fri Oct 18 15:30:03 UTC 2013

This is not a concern in WA, there's no state highways that have the same
number as US or Interstate highways.


On Thu, Oct 17, 2013 at 10:31 PM, Eric Fischer <enf at pobox.com> wrote:

> California gives State, US, and Interstate roads unique signed numbers
> within the state, but not all states do. Interstate 64 in southern Indiana
> is close enough to State Road 64 to cause frequent confusion.
> Eric
> On Thu, Oct 17, 2013 at 8:52 PM, Tod Fitch <tod at fitchdesign.com> wrote:
>> On Oct 17, 2013, at 6:11 PM, Nathan Mills wrote:
>> > On 10/17/2013 1:03 PM, Richard Welty wrote:
>> >
>> > If my GPS tells me to "turn right at the entrance to East Interstate
>> Whatever" and the sign says "North Interstate Whatever," I'm going to be
>> confused and wonder if I'm actually making the correct turn. Even more so
>> if it's a printed list of directions.
>> >
>> I can't say for the urban auxiliary (three digit) freeways, but the
>> single and double digit Interstates all seem to have on ramp signs that use
>> their nominal direction rather than the compass direction at that
>> particular location. At least that is my understanding from what I've read
>> about the rules and conventions that are supposed to be used and I have
>> never noticed an exception.
>> For what it is worth, it is my understanding that within a state the use
>> of a particular number, at least outside of triple digit urban beltways and
>> penetration Interstates, is supposed to be unique. So if I-10 goes through
>> your state, there will be no US10 nor a state highway 10. I haven't paid
>> much attention to this in other states I've visited but it seems to hold
>> true for California. If true throughout the US then it could be used to
>> help validate highway route numbers.
>> Confusion in California comes in two flavors: In Southern California
>> there is a popular tendency to call freeways by a name (e.g. "The Ventura")
>> and use the actual direction the road goes for that named segment
>> (east/west for the Ventura) when giving directions. But the named segment
>> might be on a US or Interstate with a different nominal direction. This bit
>> me years ago when we were mailing out wedding directions and I assumed the
>> on ramp from the hotel area would be labeled for the eastbound Ventura
>> Freeway when, upon checking, it turned out to be labeled for southbound
>> US101.
>> In the San Francisco Bay Area the confusion comes from the fact that the
>> only Interstate to enter the area is I-80. So all the urban auxiliary
>> (three digit) freeways have to have a suffix of 80 (even number implying
>> east/west) even if the road is north/south. So we have 280, 580, 680, 880,
>> etc. all going in different directions. Southern California avoids this by
>> having I-5, I-8, I-10 and I-15 enter the area, so I-210 is basically
>> east/west while I-405 and I-215 are basically north/south.
>> -Tod
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