1. Roundabout with square bike path
Kampen, Europa-Allee, square roundabout. Local authorities in Kampen have decided in favour of a deviating lay-out for the bike paths on the roundabouts. Instead of the usual circle, the bike paths are constructed in the shape of a square, hence the name square roundabout. This was decided in order to improve the visibility of cyclists and decrease bicycle speeds.
In re-designing Europa-Allee no fewer than six square roundabouts have been constructed (as well as one in Flevoweg). The road used to have 2x2 lanes. Due to the extension of the N50 Europa-Allee no longer has a regional function for motor vehicles. The current car intensity is approx. 10,000 mv/24h. Therefore the lay-out has gradually been reduced to 2x1 lane since 2001. Most bicycle routes are at right angles to Europa-Allee. In order to increase safety and reduce barriers all intersections have been converted into square roundabouts. Here roundabouts A and B will be discussed.
3. Old situation
In the old situation the intersections were regulated by traffic lights. Due to the length of the crossings long clearance intervals were necessary. Despite the presence of left- and right-turn lanes, some traffic lights allowed conflicts between motor vehicles making a turn and bicycles and motor vehicles travelling straight ahead. The generous lay-out encouraged high speeds.
In the re-design local authorities decided in favour of square roundabouts. The bike path forms a square instead of a circle, as recommended by CROW. According to local authorities the major advantage is that cyclists cross the lane at right angles. This provides particularly drivers of large motor vehicles with a good view of cyclists. On a traditional roundabout the visibility would be less, as the cyclists would appear from behind the vehicle. The bus company and local hauliers confirm the improved visibility.
5. Distance to bicycle crossing
Thanks to the square format and improved visibility it has been possible to reduce the distance between the bicycle crossing and the roundabout lane to a mere 50 cm (from 5 metres as recommended by CROW). As a result the square roundabout does not take up extra space. For approaching drivers, moreover, potential conflicts with bicycles and motor vehicles on the roundabout are close together. They can focus on a single point of conflict and yield to motor vehicles and bicycles on the roundabout at the same time.
6. Drawback short distance
The short distance between lane and bicycle crossing does have its drawbacks, however, particularly at high intensities. As there is no room to line up between lane and bicycle crossing, drivers leaving the roundabout may block traffic when yielding to cyclists. And drivers approaching the roundabout and having to yield to motor vehicles on the roundabout may block the bicycle crossing.
7. Connections to bike paths
Extra attention has been paid to the connections to the bike paths. Upon entering the roundabout cyclists will have to turn right (R = 4 metres = approx. 10 km/h) and then left again to follow the roundabout. This is intended to reduce their speed. This prevents cyclists from passing at speed in front of cars and being noticed too late. A disadvantage of course is the extra discomfort to cyclists, particularly when travelling side by side. In addition the distance between the ‘bicycle exit’ and the next crossing has been increased as much as possible. In this way drivers on the roundabout will know sooner whether the cyclist will cross his path.
As far as we are aware there are no accident analyses available demonstrating that square roundabouts are in fact safer than the traditional ones. SWOV did perform some observations at a square roundabout in Venray. SWOV concludes that safety differences with other roundabouts are minor: sometimes square appears to be better, sometimes the round ones. Due to the desire for standardisation (and because safety advantages cannot be demonstrated) SWOV recommends not to use square roundabouts.