Answers for "checking a gamobjects layer"

unity check collider layer

function OnCollisionEnter(collision : Collision)
 {
     if (collision.collider.gameObject.layer == LayerMask.NameToLayer("LAYER_NAME"))
     {
          Debug.Log("Touched a rail");
     }
 }

checking a gamobjects layer

if(gameObject.layer == LayerMask.NameToLayer("LAYER_NAME")){}