When should I go to hospital? Is this labor?

I've been having contractions pretty much all day. I haven't timed them but tonight I'm sure I've had at least 5 in the past hour. Should I head into the hospital? It's 45mins away. I was only 1cm dilated yesterday. Thoughts?
 I've been losing bits on my mucus plug and I've had a lot of lightening crotch as well as feeling like my pelvis is splitting apart.