Real Life Puzzle

Our motel is right next to the highway off exit 14. I need to go one exit west to exit 13 but the west on-ramp is under construction.

The back route options to the next exits are ...

Head East along North side to exit 15 (10 minutes)
Head East along South side to exit 15 (20 minutes)
Head West along South side to exit 13 (30 minutes)
Head West along North side to exit 13 (40 minutes)

The travel time between exits on the highway is 2 minutes.

What is the optimal route?
How long will it take?

See next post for hint.