Not yet, but the videos of the site and the dual carriageway layout, light right turn which explains why the escape parking lane was on the right, a miss trajectory of a vehicule pushing to the left side of the highway leads to very few options. Both the speed and the vehicule weigh if unattended for any reason could explain a straight forward trajectory crashing on the left side of the tunnel. For the bus to be driven on the lay-by can hardly been unvoluntarily given the lanes and lay-by layout. Have a look at the area on Google street view.