General Railroad Knowledge

Answer 1

Andrew,

Are you referring to American railroads?  If so, then yes, they do share their track with other railroads but only if a trackage rights agreement is in place (i.e., the railroad wishing to use the tracks pays the owning railroad a fee).  As far as how they maintain their right-of-way there is a whole army of equipment they use from tampers and ballast regulators to undercutters and rail grinders.  Some of the companies which railroads contract out to do this work include Sperry Rail Service and Loram.

In regards to passenger trains sharing track with the freights, almost in every case the line is privately owned by the freight railroads so in the case of Amtrak its trains are usually only given priority when they are not impeding freights but the railroads (for the most part) try their best to keep Amtrak  trains on time.  Anyway, this site should help, http://www.american-rails.com/.