GDT started collecting prime numbered speed limit signs on 1 February 2006 and we quickly learned that 5 M.P.H. signs are common; therefore, only 5 M.P.H. signs found in remote areas or unique locations are accepted. 3 M.P.H. signs on the other hand are not easily (nor are 2 M.P.H. signs).

On 2 November 2007, while driving to the 2007 DARPA Urban Grand Challenge, RoadHacker got a picture of this 3 M.P.H. sign. The picture was taken while driving west on I-10 in California.

The speed limit says...

+--------------+ | Empty 5 MPH | | Left Lane | ---------------- | Loaded 3 MPH | | Right Lane | +--------------+It turns out the sign contains off-by-one math.

the numbers are: 5 3 the off-by-one math is: 3! = 5 (+ 1) observe... 3! = 3 * 2 * 1 = 6GDT::BAB::BARS:: Prime Number Speed Limit Signs

**Creator:** Gerald Thurman
[gthurman@gmail.com]

**Created:** 05 November 2007

This work is licensed under a Creative Commons License.