text: Hi mammala, an "only_straight_on" does not really make sense here.
  To the west, there is an access to a parking area, from the east this is a one-way road.
  There is an "only_straight_on" sign, yes, but that's meant for a oneway service road (exit) to this street (this service road not shown in OSM though).
  Regards
  Toni