My description off Grafton road (or whichever outlet) was in reference to accessing the location Chelsea herself was discovered.
Grafton has much more traffic than briar hill or Newburg so I doubt they would've accessed it to get her to that spot, from the party that would've been back tracking, and as far as leaving after the murder, it wouldn't have been necessary to drive the tracks and come out on Grafton. That wouldve been unnecessary as leaving the murder scene would've been as simple as turning around, and following the tracks and pulling out on Grafton would've drawn way more attention. If any police are out around "bar closing" hours they'd be on Grafton and anyone around the area would know that