This literature review aims to survey Swedish and foreign design solutions to

meet mainly speed

and accessibility requirements of roundabouts and to see if foreign

experiences are relevant for

Swedish conditions. Great importance has also been given to studying to what

extent there are

"functional categories" of roundabouts.

The survey shows that lower speed and single lane in roundabouts improve

traffic safety.

Furthermore that there are good possibilities to control speed through design

e.g. using narrow,

radial entries and exits with small entry radius, entry and exit deflection

to the left, design for an

entry path curvature with small radius and traffic island.

The survey also shows that give way regulations between vulnerable road users

and motor

vehicles in Sweden can be made clearer.

The idea of dividing roundabouts and the entire traffic system into distinct

"functional

categories" is to improve traffic safety by decreasing the risk of the road

user to misunderstand the

situation. To create good categories of roundabouts it ought to be

investigated what is needed and

how it can be mediated to the road user what function category roundabout he

is in. Several

countries have, just as Sweden, a not very pronounced category classification

of roundabouts.