I found this interesting display when driving around the area and thought it would make a good place for a multi.
Look for Sign "D.L. xx".
A=sum of the two digits.
B=first digit plus 1.
Look for sign "CARL. xxx"
C=first digit.
D=second digit minus third digit.
E=first digit.
Look for a corroded brass plaque that describes when this was restored. There are two dates on the plaque.
F=last digit of the second date plus 1.
Checksum A+B+C=13
Checksum D+E+F=5
Final can be found at:
N49° 11.ABC' W122° 58.DEF'