Mark another line

Until I moved downtown seven years ago, I never realized how much underground wiring and lines existed.  Not  only  do they  exist, they are constantly being added to, removed or rerouted.  This is a little park next our condo that most of us use to walk our dogs.  Here someone has marked and flagged a line.  From one of the  flags,, I assume it is a gas line.  But who  really knows?