If you calculate a route for a car then the route can go through a bollard, by foot or bicycle that is fine but of course not for a car.
This is possibly a valid request, but out of Marble's scope: The route is not calculated directly by Marble, but by a backend which we can't fix directly. Can you please report the problem at the respective routing backend? This could be - OpenRouteService, http://openrouteservice.org/contact.php - Monav, http://code.google.com/p/monav/issues/list - MapQuest, http://www.mapquest.com/ - Yours, http://wiki.openstreetmap.org/wiki/YOURS Use the Configure button in the routing tab in Marble to deactivate some routing backends if you're unsure which one returned the current route. Please include the location of the bollard to ensure that people can check it is correctly mapped.