Oddly specific distances on signs

[Big John]

Madison (WI) Beltline, 1/8 mile sign for the 2nd of closely-spaced interchanges: http://goo.gl/maps/H0df4

[Alps]

Fractions I've seen on guide signs: 1/2, 1/3, 2/3, 1/4, 3/4, 1/5, 2/5, 1/6, 1/8, 3/8, 1/10 and several other /10 (thanks, I-676)

[agentsteel53]

if you count 1910s guide signs, or a California signing practice from the 50s, you'll get every 5th and 10th in short order. 

I've never seen less than 1/10th.  1/16th or 1/20th could ostensibly exist, but 1910s California practice was "1/10" even if you were right on top of it... where others would have used a 0, as Steve has documented in New Jersey.

[Eth]

We got 2/3s on MD 295: http://goo.gl/maps/9ZUyH

Also one on the US 19/41 Griffin, GA bypass, southbound before the GA 362 exit if memory serves.

I also recall a 1/5 somewhere on northbound I-81 in Virginia.

[Kacie Jane]

We got 2/3s on MD 295: http://goo.gl/maps/9ZUyH

Also one on the US 19/41 Griffin, GA bypass, southbound before the GA 362 exit if memory serves.

I also recall a 1/5 somewhere on northbound I-81 in Virginia.

2/3 here in Bellingham as well. http://goo.gl/maps/hqbIv

[formulanone]

2/3 on I-95 near Daytona Beach:

[hbelkins]

[PHLBOS]

Along I-95 North in Chester, PA; there's a 1/8 MILE advance BGS for Exit 6 (PA 320/352).

[getemngo]

Minnesota commonly uses 1/5 mi. for advance warning signs.  Do other states use oddball fractions like that?

Michigan has a few "Ramp 1/8 mile" type of signs, but 1/8 is far less weird than 1/5.

[kphoger]

Minnesota commonly uses 1/5 mi. for advance warning signs.  Do other states use oddball fractions like that?

Michigan has a few "Ramp 1/8 mile" type of signs, but 1/8 is far less weird than 1/5.

Interesting that we think that, isn't it (and I agree with you)?  After all, mileposts and reflectors often appear in frequencies of 1/10 or 1/5, not to mention that 1/5 in decimal form is simpler than 1/8 (0.2 compared to 0.125).  Maybe it's because we're so used to seeing 1/2 and 1/4 that we like to be able to divide 1/4 in half.

In reality, the only way I have of visualizing 1/8 mile is to think of it as a city block (I walked a lot when I lived in the Chicago area, where blocks are generally 1/8 mile long).  I have no point of reference as to how far 1/5 mile is, except maybe fractional mileposts.

I'm not sure there is a "good" measurement for distances of less than 1/4 mile.  It's hard to visualize 700 feet or 300 yards, for example.  Perhaps distances of less than 1/4 mile should just fudge it and say 1/4 mile?

[agentsteel53]

I have trouble with feet.  fractions of miles can be translated to fractions of minutes because ~60mph is such a typical speed on roads where those distances are used. 

so if I see a sign which says "3/4 mile", I know I've got about 45 seconds.

"2000 feet"?  ehh well that's, I suppose, 2/5 of a mile, but it takes me some time to calculate it.  as for distances under 1/4 mile, which tend to be written as 500 or 1000 feet, then you're talking about estimating how far to that tree, which is not a skill which I have.  I'd rather have "1/10th" mile, because I know that is 6 seconds, than 500 feet.

[kphoger]

I don't think it matters what you put for a distance of less than ¼ mile:  by the time you figure it out in your head, you're there!

[agentsteel53]

Perhaps distances of less than 1/4 mile should just fudge it and say 1/4 mile?

I disagree.  I think that distances should always be greater than what is posted.

exit 23 here in San Diego off I-8 is tricky because it has only one advance sign with a distance: 1 mile.  the exit is around a fairly sharp right curve with a bluff just inside of it - it really sneaks up on you... and it's 0.85 miles from the sign.

guess which exit I had only about a 50/50 chance of nailing before I actually calculated the distance and memorized it for future reference.

[Pete from Boston]

Somewhat off-topic but related are the littering fine signs in Connecticut, which are some oddly non-round number like $219.  Sometimes I get so confused when I see them that the trash bag I was about to stop throwing falls right out of my hand.

[agentsteel53]

Somewhat off-topic but related are the littering fine signs in Connecticut, which are some oddly non-round number like $219.  Sometimes I get so confused when I see them that the trash bag I was about to stop throwing falls right out of my hand.

I think fines tend to get inflation-adjusted once every several years.  so it probably started out something sensible like $100 back in the day.

[1995hoo]

.... Perhaps distances of less than 1/4 mile should just fudge it and say 1/4 mile?

I recall a sign on I-66 in Virginia (it was removed last year) that originally listed 1/4 mile to the exit for southbound I-495 but was later changed to say 1/10 of a mile. The sign was attached to the Virginia Lane overpass and can be seen on Street View: http://goo.gl/maps/scbLG  (The original sign was posted in 1982 and was altered by affixing "1/10" over "1/4" and this sign may have been a replacement for that.) Off the top of my head, I'm not sure what the current sign says. A new gantry was erected just to the east of that overpass as part of the 495 Express Lanes project and the sign was relocated to the new gantry at that time. Either way, the old sign seems like it could have just said "NEXT RIGHT" and have been equally effective. That's the only exit from westbound I-66 at I-495 since it's a partial interchange.

[Eth]

exit 23 here in San Diego off I-8 is tricky because it has only one advance sign with a distance: 1 mile.  the exit is around a fairly sharp right curve with a bluff just inside of it - it really sneaks up on you... and it's 0.85 miles from the sign.

guess which exit I had only about a 50/50 chance of nailing before I actually calculated the distance and memorized it for future reference.

In a similar vein, on westbound I-20 in Georgia just past the Exit 68 offramp there's a 2-mile advance sign for Exits 67B-A (I-285, a pretty damn important set of exits). The distance from there to the Exit 67B gore point? 1.1 miles. That's on my daily commute, so I'm used to it being wrong, but I can only imagine how much panic this ends up causing out-of-towners.

[ARMOURERERIC]

21 MPH signs are very common in San Diego County when on tribal land driving the entrance road to a casino.

[Brandon]

Minnesota commonly uses 1/5 mi. for advance warning signs.  Do other states use oddball fractions like that?

Michigan has a few "Ramp 1/8 mile" type of signs, but 1/8 is far less weird than 1/5.

Interesting that we think that, isn't it (and I agree with you)?  After all, mileposts and reflectors often appear in frequencies of 1/10 or 1/5, not to mention that 1/5 in decimal form is simpler than 1/8 (0.2 compared to 0.125).  Maybe it's because we're so used to seeing 1/2 and 1/4 that we like to be able to divide 1/4 in half.

In reality, the only way I have of visualizing 1/8 mile is to think of it as a city block (I walked a lot when I lived in the Chicago area, where blocks are generally 1/8 mile long).  I have no point of reference as to how far 1/5 mile is, except maybe fractional mileposts.

I'm not sure there is a "good" measurement for distances of less than 1/4 mile.  It's hard to visualize 700 feet or 300 yards, for example.  Perhaps distances of less than 1/4 mile should just fudge it and say 1/4 mile?

You pretty much nailed why.  In many areas, blocks are 1/8th of a mile in length as this splits a mile up very nicely with survey chains.  One chain is 66 feet, and one furlong is 660 feet or 10 chains.  There are 100 links to a chain and 4 rods (16-1/2 feet or 25 links) to a chain.  This is also why many streets have rights-of-way of 66 feet and alleys are typically 16-1/2 feet wide.  It's one chain and one rod respectively.  One block, an 8th of a mile is exactly one furlong long in survey terms.  Hence, a mile is 8 furlongs, 80 chains, 320 rods, or 8,000 links long.  All of these fit very nicely into our survey system (PLSS) for cities (like Chicago) and townships.  As an aside, one acre is one furlong by one chain (hence why 160 fit into a quarter section, and 640 fit into a section, and why an acre is not a square unit of measurement).

Fractions like 1/5th or 1/6th, or decimals of a mile (0.10, 0.20) do not make sense in our survey system due to this.  It's also one of my personal arguments against the adoption of the SI for roads and surveying.  We've used a very logical system, and converting it to metric would screw it up.

[agentsteel53]

In a similar vein, on westbound I-20 in Georgia just past the Exit 68 offramp there's a 2-mile advance sign for Exits 67B-A (I-285, a pretty damn important set of exits). The distance from there to the Exit 67B gore point? 1.1 miles. That's on my daily commute, so I'm used to it being wrong, but I can only imagine how much panic this ends up causing out-of-towners.

I wonder if someone accidentally switched the work orders for the 2-mile and 1-mile advance signs?

for the opposite problem, I-215 southbound in San Bernardino approaching the 215-60-91 junction has a next-three-exits sign which says 1/4 mile.  that is the first notification that you get.  it's actually 1 1/4 mile; they typoed it.  as 215 exits itself, I've seen a lot of people panicking and changing lanes.  someone needs to go up there with an adhesive vinyl "1", and soon.

[roadman]

In a similar vein, on westbound I-20 in Georgia just past the Exit 68 offramp there's a 2-mile advance sign for Exits 67B-A (I-285, a pretty damn important set of exits). The distance from there to the Exit 67B gore point? 1.1 miles. That's on my daily commute, so I'm used to it being wrong, but I can only imagine how much panic this ends up causing out-of-towners.

I wonder if someone accidentally switched the work orders for the 2-mile and 1-mile advance signs?

Another possibility - how long is the distance between the interchange ramps?  For cloverleaf interchanges, MassDPW practice in the 1960s and 1970s was to measure the distance from the advance signs to the intersection of highway baselines (usually somewhere within the center of the cloverleaf).  Only the last advance sign for the first exit was measured to the gore point of the exit ramp.

[mapman1071]

 
I-19
2 KM
1 KM
500 Meters

[Eth]

In a similar vein, on westbound I-20 in Georgia just past the Exit 68 offramp there's a 2-mile advance sign for Exits 67B-A (I-285, a pretty damn important set of exits). The distance from there to the Exit 67B gore point? 1.1 miles. That's on my daily commute, so I'm used to it being wrong, but I can only imagine how much panic this ends up causing out-of-towners.

I wonder if someone accidentally switched the work orders for the 2-mile and 1-mile advance signs?

Another possibility - how long is the distance between the interchange ramps?  For cloverleaf interchanges, MassDPW practice in the 1960s and 1970s was to measure the distance from the advance signs to the intersection of highway baselines (usually somewhere within the center of the cloverleaf).  Only the last advance sign for the first exit was measured to the gore point of the exit ramp.

It's 1.4 miles from the sign to the I-285 overpass, and 1.6 miles to the Exit 67A ramp. No matter how you look at it, they goofed.

[The High Plains Traveler]

There used to be a lot of 800 M signs in Canada, vestiges of signs that formerly read "1/2 mile" .

[kphoger]

US-400 in Cherokee, Kansas:

Approaching the four-way stop at K-7, there are two "stop ahead" signs (W3-1) westbound, and there are two eastbound as well.  They now sport plaques reading 1300 FEET and 550 FEET, appropriately.  Both directions use exactly the same figures (I assume they're also at exactly the same distances from the intersection).  The only thing I can figure is that they correspond roughly to a quarter-mile and a tenth-mile.