When a a city features a "loop" that routes interstate traffic around the heart of a city, the loop name is in
the 200, 400, or 600 range and derives its number from the interstate that in branches from. In Dallas,
for example, the LBJ Freeway is numbered I-635 because it loops around I-35.
Interstates are marked with mile markers, one every mile. Mile markers on an interstate begin at the
border of each new state. They start at the southern border and increase as you move north for odd
numbered interstates. They start at the western border of the state and increase as you move east for the
east/west routes.
If an interstate does not start at the state's border, the mile markers begin at the beginning of the
interstate.
Normally, you would expect that the street address of a location on an interstate should be the mile
marker number. Nearby Explorer currently contains a bug that returns a street number for interstates that
are close to the street numbers of nearby streets.
The exits on an interstate are indicated by the mile marker. Exit 5 is always located between mile marker
5 and 6. If there are two or more exits within a mile, their designation includes both the mile marker and
a suffix letter. If there were three exits at marker 5, they would be labeled 5A, 5B, and 5C.
When you see exits in the map data, they are treated like streets, but the street name is the exit number.
Therefore, it is not uncommon to see streets entering and exiting the interstate with names such as 8 or
8A.
Interstates are named with I- followed by the interstate number. I-40 E refers to the eastbound lanes of
interstate 40.
US highways are labeled with the prefix "US-" followed by the route number. US-67 refers to US
highway route 67.
State highways are named with the state abbreviation followed by the highway number as in IN-62 for
Indiana highway 62.
County roads are labeled with "County Road" or some abbreviation such as "CR" followed by the
number of the road as in CR 1429.
Approaching
If the Approaching item on Nearby Explorer's Nearby screen is checked, the program alerts you about
nearby streets as you approach them.
If the street appears to be a cross street, it says the street name and "ahead." If it sees the street only to
the right or left, it adds "Right Side" or "Left Side" to its announcement of the street name.
Distance Updates
In addition to the side of the street, the announcement also estimates the distance to that intersection. As
you approach the street, the distance updates to reflect your new position.
If you do not want to hear the progressive updates about the distance to the next intersection, follow
http://tech.aph.org/plus_doc.htm
