Newcastle University Rolling Load Facility (NUROLF) is John Knapton's full scale rolling load facility. It is in the Cassie Building at Newcastle University and comprises a truck which shuttles back and forth over a 9m x 2m test area. The truck is powered by a 60HP electric motor controlled by a microprocessor so as to simulate different combinations of speed, acceleration and braking. The facility has a maximum axle load of 14,000kg (14t) and can be set to automatically wear out a pavement section. It is used for research and commercial testing and has been used to verify pavement sections worldwide. The following pictures show its details and typical output. It has been in continuous service since 1993 and has made a significant contribution to national and international standards for pavements.
Below, the load wheel is driven back and forth over the test section so that a combination of vertical and horizontal force is applied to the pavement section. Most full scale pavement test facilities apply only a vertical load and this limits the realism of the results. Because horizontal forces have been shown to be important in pavements surfaced with pavers, this is a crucial feature. It allows paver patterns and shapes to be compared realistically. It has been used in the development of UK specifications for bedding sands. Many highway authorities have used NUROLF to prove their design prior to constructing new streets. The City of Amsterdam is one of our major clients.
The load can be adjusted by filling the twin water tanks on the vehicle. Before entering NUROLF service, the vehicle served as a gulley emptying device. This means it has a dirty water tank and a clean water tank. This allows fine adjustment of front and rear axle loads, although normally we use maximum weights to accelerate pavement failure.
The picture below shows the NUROLF guidance system. Vertically mounted guide wheels run on an inverted T steel rail. This ensures that NUROLF applies maximum load to the centre of the pavement. Also shown is the differential through which drive is transmitted to the rear axle.
Typical NUROLF output is shown below. The rut in the pavement surface is surveyed and is magnified 30 times to show the effect of the test vehicle on the pavement. This surface was produced after 100,000 standard 8,000kg axles had trafficked the pavement.
