For an effective thermoplastic pavement marking replacement strategy, the rate at which the marking’s retro-reflectivity deteriorates in service must be well established in order to avoid re-stripping that is too soo...For an effective thermoplastic pavement marking replacement strategy, the rate at which the marking’s retro-reflectivity deteriorates in service must be well established in order to avoid re-stripping that is too soon or too late. Against this background, this paper undertook a review of models that deal with degradation of thermoplastic pavement markings under different traffic and environmental conditions in order to establish service life and the terminal retro-reflectivity levels that have informed re-striping. Service life in the context of this paper is the time taken for a newly-installed marking to degrade to some minimum retro-reflectivity level below which motorists would find it difficult to navigate on the carriageway under night-time and poor visibility conditions. It was established that the minimum retro-reflectivity requiring re-stripping intervention reported varied, although commonly-adopted values tended to range from 50 mcd/m2/lx to 150 mcd/m2/lx. A number of empirical models, based on site specific conditions, have been developed by researchers using field data, to estimate marking retro-reflectivity at any time since placement. Whereas some of the models used time as the only independent variable, others used a combination of time, traffic level and a few other parameters to estimate retro-reflectivity. Even though degradation of marking retro-reflectivity is a reflection, among other things of material degeneration impacted by environmental and service conditions, almost all the models reviewed failed to consider environmental factors. Additionally, for some of the models, non-inclusion of the initial retro-reflectivity level and their generally low coefficient of determination statistic erode the confidence in their reliability.展开更多
文摘For an effective thermoplastic pavement marking replacement strategy, the rate at which the marking’s retro-reflectivity deteriorates in service must be well established in order to avoid re-stripping that is too soon or too late. Against this background, this paper undertook a review of models that deal with degradation of thermoplastic pavement markings under different traffic and environmental conditions in order to establish service life and the terminal retro-reflectivity levels that have informed re-striping. Service life in the context of this paper is the time taken for a newly-installed marking to degrade to some minimum retro-reflectivity level below which motorists would find it difficult to navigate on the carriageway under night-time and poor visibility conditions. It was established that the minimum retro-reflectivity requiring re-stripping intervention reported varied, although commonly-adopted values tended to range from 50 mcd/m2/lx to 150 mcd/m2/lx. A number of empirical models, based on site specific conditions, have been developed by researchers using field data, to estimate marking retro-reflectivity at any time since placement. Whereas some of the models used time as the only independent variable, others used a combination of time, traffic level and a few other parameters to estimate retro-reflectivity. Even though degradation of marking retro-reflectivity is a reflection, among other things of material degeneration impacted by environmental and service conditions, almost all the models reviewed failed to consider environmental factors. Additionally, for some of the models, non-inclusion of the initial retro-reflectivity level and their generally low coefficient of determination statistic erode the confidence in their reliability.
