Dire Straits on the Roundabout

Roundabouts are a different thing altogether. Their construction differs significantly from normal road construction.
One key factor alone is the permanent bend – the small radius presents a challenge, not only to traction of the road paver.

In most countries the traffic is increasing continuously. Long tailbacks are a common feature in inner cities at rush hour, especially at traffic junctions. The fault often lies with crossroads equipped with expensive traffic light systems which bring the traffic to a standstill.

On crossroads there are 32 danger spots as a result of vehicles crossing each other’s ways. Driving speeds are often high.	On roundabouts these danger spots are reduced to 8. A roundabout allows driving at a low speed only.

The future belongs to the roundabout
On roundabouts, on the other hand, the traffic sorts itself into different directions quite independently. All vehicles keep moving irrespective of how many roads may lead to the roundabout. Road users can turn off faster or even turn around, thus considerably lowering the risk of an accident (see illustration). It is therefore no wonder that roundabouts are becoming more and more common in cities throughout the world.

Paving in full-road width avoids longitudinal joints
As on any road building site, the construction team for a roundabout starts preparing the sub-base. On the roundabout building site, too, the pavement is built layer after layer from aggregate base, base course and binder course through to wearing course. In order to avoid longitudinal joints within the 360° bend, paving across the full width is recommended when laying the topmost wearing course. If the roundabout is to be connected to already existing roads, manual placing or removal of mix at the access points facilitates and speeds up the paver’s work.

More and more roundabouts channelizing traffic.

Good planning first
So as to remain in full control of all the parameters, it is always advisable before work starts on a roundabout to prepare a work schedule which specifies the individual working stages and action of the paver. The use of additional construction machinery can also be considered in case of need. Use of front end loaders or mechanical shovels, for instance, can be helpful when it comes to paving at points which are not so easily accessible. In addition, VÖGELE offer a variety of optional equipment, which on a roundabout building site helps reduce manual work to a minimum: the kerbstones laid along the full circumference of the roundabout still before the paver even starts its work are used as a reference for NIVELTRONIC, for instance, the VÖGELE Automated Grade and Slope Control System.

The trick with the traction
Building a roundabout is a true challenge. When working with a VÖGELE paver of the SUPER class, however, nobody needs to fear roundabout construction. A VÖGELE will manage the job absolutely reliably. Both types of VÖGELE pavers, wheeled or tracked, are fully capable of handling any work on a roundabout building site. Compared with standard road construction, building a roundabout is considered to be difficult. The main reason for this is the tight space available to the paver during construction. Here traction is crucial. Based on their overall design, VÖGELE pavers stand out through excellent properties as far as traction is concerned. For special applications where exceptional tractive power is required, as the construction of roundabouts, VÖGELE recommend to make use of the paver’s Screed Assist feature. Pressure set to some 25 bar supports the paver’s tractive effort during its circular movement. This is particularly helpful above all when paving in larger widths.