I live in the area, and your commute is completely do-able and realistic. I have a 24 mile commute that I bike/bus/Metro. You might be able to do a partial bus ride and knock down the 14 miles, or just go for it! At 14 mph average, it will take about 1 hour. Your 1 hour 15 minutes estimate puts you at a little over 11mph, and while I can't speak for your fitness level/specific commute, that trail should allow you a little faster pace than that during commuting hours. In traffic I tend to average 12mph with stoplights, etc. Nowadays in the morning with no traffic and good light timing/blinking lights, I'm definitely 15+ mph.