I took this off this website.
DRIVING THE BAJA HIGHWAY
Basic Arithmetic of the Baja Highway
Width of the pavement: 19 feet
Width of the shoulder: 0 feet
Width of a truck/bus/RV: 8 feet
Added width for mirrors: 1 foot
Width used by two passing trucks/etc: 18 feet
Safety separation used by
two passing trucks/etc: 1 foot
Room left for a bicycler: 0 feet
The highway was constructed to just accommodate two passing 8-foot vehicles, and no more! Many of the roadsides drop off anywhere from a few feet to a few hundred feet (in these extreme cases, there will usually be a low guard rail right at the edge of the pavement). Also, the edge of the pavement will often have chunks broken off or washed away, leaving "edge potholes" which have to be dodged.