In regards to "there is nothing to imply oneway", the median in the middle and the narrow lanes around the median are enough for me to be confident that this is a traffic calming installation and that each way is one way due to this. There are plenty of roads in the country that are divided with median, roundabouts, and other obstacles which lack markings, but because of general traffic laws and what side of the road we drive on in the country, it is safe to assume one way in each direction on these roads.