What, pray tell, do guys with large penises have to do with highway markers?
Here’s a ton of info about California’s mile markers.:
(I can’t recommend that entire site enough if you’re a highway geek like me.)
I noticed this when driving through missouri just last week. I counted about 1200 of the things before I got tired of that “let’s kill time” car game. I just assumed they had a government grant for road signs or something and were milking it for all it was worth.
The straight dope:
When law enforcement officers fill out crash reports, they have to include the location of the crash so it can be tabulated for hazard mitigation or enforcment programs, and for other reasons including insurance matters. They have to record the distance from some upstream known point like an intersection or numbered route, toward the next route or reference point. In urban areas or areas of high crash rates, the closer together the reference points are, the more accurate the crash location stats will be. With tenth of mile points marked, they don’t have to guess or estimate the location.
Oddly, although UK road distances are measured in miles, we have distance markers in metres at the side of motorways. They’re not really labelled as such, though.
There are posts every 100 metres which are numbered with the distance from one end of the motorway in kilometres, plus an arrow pointing in the direction of the nearest emergency phone (which are located every 1000 metres).
Recently, much larger and more prominent blue signs have appeared every 500 metres, which show the same distance numbers. You can see both types here.
The blue numbers don’t always go up e.g. 12.0, 12.5, 13.0 etc - after junctions the locations often get shifted so you’ll have 53.3, 53.8, 63.3 and so on.
There’s more info about them here, although in my experience most drivers don’t have a clue what the signs mean.
To expand on what I said above, here’s more of the straight dope from the USA Federal Highway Administrations’s Manual on Uniform Traffic Control Devices (http://mutcd.fhwa.dot.gov, which has the force of law on all USA roads, although state laws can amend it in certain cases:
"Section 2E.54 Reference Location Signs and Enhanced Reference Location Signs (D10-4, D10-5)
Support:
Reference Location (D10-1 through D10-3) signs and Intermediate Reference Location (D10-1a through D10-3a) signs and their applications are described in Section 2D.46.
There are two types of enhanced reference location signs:
Enhanced Reference Location signs (D10-4), and
Intermediate Enhanced Reference Location signs (D10-5).
Standard:
Except as provided in the option below, Reference Location (D10-1 through D10-3) signs (see Section 2D.46) shall be placed on all expressway facilities that are located on a route where there is a reference location sign continuity and on all freeway facilities to assist road users in estimating their progress, to provide a means for identifying the location of emergency incidents and traffic crashes, and to aid in highway maintenance and servicing.
Option:
Enhanced Reference Location (D10-4) signs (see Figure 2E-45), which enhance the reference location sign system by identifying the route, may be placed on freeways or expressways (instead of Reference Location signs) or on conventional roads.
To augment an enhanced reference location sign system, Intermediate Enhanced Reference Location (D10-5) signs (see Figure 2E-45), which show the tenth of a kilometer (mile) with a decimal point, may be installed along any section of a highway route or ramp at one tenth of a kilometer (mile) intervals, or at some other regular spacing.
Figure 2E-45 Enhanced Reference Location Signs
Standard:
If enhanced reference location signs are used, they shall be vertical panels having blue or green backgrounds with white numerals, letters, and borders, except for the route shield, which shall be the standard color and shape. The top line shall consist of the cardinal direction for the roadway. The second line shall consist of the applicable route shield for the roadway. The third line shall identify the kilometer (mile) reference for the location and the bottom line of the Intermediate Enhanced Reference Location sign shall give the tenth of a kilometer (mile) reference for the location. The bottom line of the Intermediate Enhanced Reference Location sign shall contain a decimal point. The height of the legend on enhanced reference location signs shall be a minumum of 150 mm (6 in). The height of the route shield on enhanced reference location signs shall be a minimum of 300 mm (12 in).
The background color shall be the same for all enhanced reference location signs within a jurisdiction.
The design details for enhanced reference location signs shall be as shown in the “Standard Highway Signs” book (see Section 1A.11).
Enhanced reference location signs shall have a minimum mounting height of 1.2 m (4 ft) to the bottom of the sign in accordance with the mounting height requirements of delineators (see Section 3D.04), and shall not be governed by the mounting height requirements prescribed in Section 2A.18.
The distance numbering shall be continuous for each route within any State, except where overlaps occure (see Section 2E.28). Where routes overlap, enhanced reference location sign continuity shall be established for only one of the routes. If one of the overlapping routes is an Interstate route, that route shall be selected for continuity of distance numbering.
The distance measurement shall be made on the northbound and eastbound roadways. The enhanced reference location signs for southbound or westbound roadways shall be set at locations directly opposite the enhanced reference location signs for the northbound or eastbound roadways.
Guidance:
The route selected for continuity of distance numbering should also have continuity in interchange exit numbering (see Section 2E.28). On a route without enhanced reference location sign continuity, the first enhanced reference location sign beyond the overlap should indicate the total distance traveled on the route so that road users will have a means of correlating their travel distance between enhanced reference location signs with that shown on their odometer.
Standard:
Except as provided in the option below, enhanced reference location signs shall be installed on the right side of the roadway.
Option:
Where conditions limit or restrict the use of enhanced reference location signs on the right side of the roadway, they may be installed in the median. In urban areas, Intermediate Enhanced Reference Location signs may be installed on the right side of the roadway, in the median, or on ramps to replace or to supplement the reference location signs. Enhanced Reference Location signs may be installed back-to-back in median locations."
The devil makes them do it.