if unexpected adverse driving conditions slow you
down, you may drive up to 2 extra hours to complete
what could have been driven in normal conditions.
This means you could drive for up to 13 hours,
which is 2 hours more than allowed under normal
conditions. Adverse driving conditions mean things
that you did not know about when you started your
run, like snow, fog, or a shut-down of traffic due to
a crash. Adverse driving conditions do not include
situations that you should have known about, such as
congested traffic during typical “rush hour” periods