TY  - JOUR
PY  - 2005//
TI  - Durability test of retro-reflecting materials for road signs at Nordic test sites
JO  - Traffic engineering and control
A1  - Sorensen, K.
A1  - Lundkvist, SO
SP  - 13
EP  - 17
VL  - 46
IS  - 1
N2  - A durability test of retro-reflecting materials for road signs is being carried out at nine test sites at different locations in the Nordic countries. The test sites were established in 1997 by the NMF group, a voluntary Nordic research cooperation. The R subA values (coefficient of retro-reflection) of the samples of the retro-reflecting materials have been measured in the 0,33 degrees /5 degrees geometry (0,33 degrees observation and 5 degrees entrance) on a regular basis since 1997. The measurements have been performed by local people with locally used instruments. In the autumn of 2003, measurements were done by a single person using a single and well tested instrument, resulting in a 'reference' set of data with less variation than on previous occasions that is particularly well suited for analyses such as presented in this article. The test sites and the R subA values of the samples are introduced and an analysis is carried out in steps resulting in an ageing model showing that the load of exposure differs from test site to test site and that the R subA values of the materials degrade at different rates. The model is further discussed and the implications of the model are considered.     <p>Language: en</p>
LA  - en
SN  - 0041-0683
UR  - http://dx.doi.org/
ID  - ref1
ER  -