Road Sign Math

We recently had significant controversy on Road Sign Math over Mile Marker. This sign pushed the boundaries of rule 3 that only allows natural numbers, and required the creation of rule 3a regarding implied decimals.

It is somewhat common for mile markers to be given in tenth of a mile increments near metropolitan areas or on major freeways. Many states require that the tenth be indicated with a decimal, like “.7″. However, not all. Mile Marker itself shows this being done using a different colored background. The sign on the right is found on the New Jersey Turnpike and shows another representation of tenths of a mile.

The US Department of Transportation Federal Highway Administration Manual on Uniform Traffic Control Devices is not silent on this topic. Sepcifically, it has references and indicates that the decimal point is required. Several states either are silent in their MUTCD or simply echo the US DOT requirements (Iowa’s UTCD does not provide guidance for reference location signs anywhere). You will note that the example sign from New Jersey, while being correct in it’s use of a horizontal line, is invalid since it lacks the decimal point required.

After much consideration, rule 3a has been added that specifies implied decimals must be observed. The lack of a physical “.” on a sign that clearly implies it does not make the sign valid for use. This is in-line with the original intent of the sign, and also complies with the mandate of the MUTCD.

Mile Marker has been deemed invalid, and has been removed from the database, however the posting for it is still available with the feedback for reference.

Keep the hunt for mathematically significant roadsigns strong! Remember…