For the same reason benches got handles, a new design of very short benches is introduced. These benches can fit only one person, so they prevent sleeping in public space. They are usually found in groups of three or four, presenting an image of a gathering and socialising, while actually keeping people away from each other.
An attempt of sitting on a '1 and 1/2' bench together; Vienna, May 2011
Old benches in parks used to be put there for people to sit together, so that more than 2 or 3 persons could use them at the same time. But then, people could also sleep on them, cause their average length was only a little shorter than a real bed.
In the past 10 years, there is a tendency to install benches with handles in parks, at bus and train stations. The space between the handles is enough for only one person, so people sitting together on the bench are separated by handles. This way, a body of an adult person could not fit to lay down. Because the presence of homeless people in city centres is less and less tolerated, this became a very popular solution.
All metro stations in Rotterdam are furnished with this type of bench: cold metal and handles; Rotterdam, March 2012