Assessments of the performance of road markings is carried out regularly to various degrees in the Nordic countries. The main aim of the Nordic road marking assessment study is to show possible differences in road marking performance between Denmark, Norway and Sweden. Possible differences between road marking performance, dependent on region, country, type of road and AADT (Annual Average Daily Traffic) are studied. Furthermore, a comparison between the TEN-T and the non-TEN-T road network is made. As 2018 is the second year of the project, a comparison between the results for 2017 and 2018 is also made.
A Nordic certification system for road marking materials has recently been introduced in Norway and Denmark and will be introduced in Sweden 2019. This means that a documented product approval (i.e. certification) will be required for use of the material on roads managed by the national road authorities. The requirements are introduced successively as the existing contracts expire. Therefore, one aim is also to study the road marking quality before and under the introduction of the new certification requirements. Continuous assessments give the opportunity to react and adjust the requirements in the future, if the performance does not develop as expected.
The study is based on physical mobile road assessment measurements carried out in Denmark, Norway and Sweden by Ramböll. In total 71 road objects were measured in Denmark, 124 in Norway and 434 in Sweden. The following variables were studied: retroreflectivity of dry and wet road markings, relative visibility of dry and wet road markings, relative pre-view-time (pvt) of dry and wet road markings and cover index.
The results show that the retroreflectivity requirement of dry road markings (150 mcd/m2/lx) is roughly fulfilled in 50 % of the measured objects. Road markings in Denmark have lower retroreflectivity than those in Norway and Sweden. Some retroreflectivity values are low, e.g. motorway edge lines in Denmark. However, this is compensated for by a large area, which nevertheless means good visibility. Contrary: edge lines on Swedish two-lane roads have high retroreflectivity, which would imply good visibility. However, the road marking area is small, thus reducing the visibility in comparison with both Danish and Norwegian edge lines.
Regarding wet road markings, road markings in Norway have higher retroreflectivity than Denmark and Sweden for every road class. This can probably be explained by the fact that Norway often has inlaid road markings, a solution seldom used in Denmark and Sweden. When analysing the results for wet road markings it should be noted that significant deviations be-tween the results from the mobile measurements and the hand-held measurements were shown during the annual validation of mobile instruments in 2017 and 2018 and therefore, the results for wet road markings should be interpreted with care.
A comparison between the retroreflectivity on the Trans-European Transport Network (TEN-T) and other roads showed that there were only minor differences between the TEN-T and other roads in Denmark, while in Norway and Sweden there are somewhat higher levels for the TEN-T network. The results for relative visibility show larger differences between TEN-T and non-TEN-T and in all three countries, the relative visibility is higher for the TEN-T road network. However, studying the rela-tive pre-view-time shows that in all countries, this measure is lower on the TEN-T roads, due to higher speed limits on the TEN-T road network. For Norway and Sweden, the differences in pvt between TEN-T and other roads are rather small, while for Denmark the difference is significant, and the relative pre-view time is about 0.6 s shorter on the TEN-T roads than on other roads.
There is no significant difference in cover index between the countries, but between road classes the difference is significant. Lane and centre lines seem to have a higher cover index than edge lines. This is difficult to explain, but the reason might be that lane and centre lines are reconditioned almost every year, due to many wheel roll overs. If so, measurements were car-ried out on almost new lane and centre lines, while the edge lines might have been applied in earlier years. Another explanation might be that the edge lines are profiled to a higher extent than the lane and centre lines.
In the second year of the project, it is not possible to study any effect of the Nordic certification system for road markings. However, in the coming years, some effects might be possible to register.
In conclusion, there is no large difference in road marking performance between the three countries and comparing the re-sults between 2017 and 2018 shows no major differences on country level. For both 2017 and 2018 the main conclusion is the poor visibility of edge lines on two-lane roads in Sweden and the good performance of wet road markings in Norway.