Can I walk?

Yes.  The 5K has no time restriction.  The Half Marathon does.  You need to complete the event within 4 houts. That equates to a little faster than a 17 minutes per mile pace.  There will be a trail vehicle.  If you fall behind the trail vehicle, you may catch a ride.  Otherwise, you are totally on your own.  Traffic cones will be picked up.  Officers and volunteers will not be on the course once the trail vehicle arrives at their areas.