"Measurement and signs in Puerto Rico" joke

Having just returned from a brief visit to Puerto Rico, I must report how well the mixed english/metric system has made live easier on the island.
All speed limits are posted in Miles Per Hour
All distances on the highway are posted in Kilometers
(however short distances are posted in feet & inches)
Therefore it is normal to see the following three signs next to each other:
SPEED
LIMIT55
MPH
PONCE
55 KMSAN JUAN
285 KM
MAXIMUM
CLEARANCE
12'6"
Just think how this must translate to one of the old common math problems assigned in school:
Train A (comprised of an engine, 22 box cars and a caboose) leaves San Juan at 12 noon south-bound for Ponce.
Train B (comprised of an engine, 16 box cars and a caboose) leaves Ponce 15 minutes later north-bound for San Juan.
There is only one stretch of double track where the trains may pass safely. This starts 100KM south of San Juan and is 2.5KM long.
It is 230KM from San Juan to Ponce (from front of engine)
Train A travels at 45MPH
Engines are 52'6" long
Box Cars are 42'8" long
Cabooses are 30'4" long
What is the slowest and fastest speeds at which Train B may travel to safely pass Train A?
Or, of a slightly more topical nature:
[Radio Anouncer] Hurricane Hugo is 120 KM East South East of the Island and is aproching at 18 Miles Per Hour. That means we should expect the center of the storm to pass over this area in... er... about... ah... But, first a word from our sponsor.