Monitoring and improving the quality of road markings in Perugia - ‘SAFE MOBILITY’
The Global status report on road safety published by the World Health Organisation in 2009, states that more than 1.2 million people die on the world’s roads every year and 50 million others are injured. Over 90% of the deaths occur in low and middle-income countries. Perugia is taking action and has started a research project aiming to define a ‘modus operandi’ for the in-situ quality measurement of road markings in the city.
Of course prevention is the best way to improve road safety. By building safer vehicles and roads, encouraging greater public transport use and improving road user behaviour in general things can improve.Road marking improvements are one of the most effective road safety mechanisms, even in the short term: UK research has shown that the typical rates of return on investment from schemes to improve road markings range from 500% to 1,500 %.CIRIAF (Inter-university Centre of Research on Pollution by Physical Agents) in co-operation with the Municipality of Perugia has started a research project aiming to define a ‘modus operandi’ for the in-situ quality measurement of road markings, accounting for the characteristics of the site to:optimise the maintenance programme for road marking; give the municipalities a tool to verify the quality of the application of road markings in order to assess if the requirements given in tenders are fulfilledassess the safety of road markings.The use of road markings has grown exponentially with the use of the motorcar, initially as a result of the first National Conference on Street and Highway Safety in Washington DC in 1925, to what is now a multi million Euro international road safety industry, serving all developed and developing nations. The effects of pavement marking on traffic safety and driving comfort are considerable. Efficient and durable road horizontal marking are essential, both for the users and for the administrators. From the users’ point of view, pavement marking provides an ‘optical path’ which comprises a sufficient contrast of colour and luminance with the road surface. The costs of provision and the relative performance of different surfaces, influence investment choices and the programme planning of road marking maintenance.There are four basic road marking materials, all of them using glass beads to improve retro- reflectivity properties: Paint, thermoplastic, ‘two-component’ markings and pre-formed road markings or ‘tapes’.In The European Union, the standards on the Performance of Road Markings were introduced in August 1997. In particular the European Standard EN 1436 specifies the performance standards for road users of white and yellow road markings, based on luminance (colour), day-time visibility, night-time visibility and skid resistance, combined with durability. Furthermore, the standards also describe the methods of measuring the following parameters: Luminance Coefficient in day conditions QdRetro-reflectivity (RL) in night conditions (dry, wet and rain)Luminance Factor (β)Skid resistance (SRT)At the moment, municipalities all over Europe usually undertake road marking maintenance through the combined use of their internal staff and outside contractors. The evaluation of the work of contractors is made at the end of the operation and doesn’t enable the management to assess the efficiency during the course of the work. The current evaluation is made purely by verifying the products used, in terms of quantity, and by a visual judgment of the amount of paint used.For this reason CIRIAF, together with the Municipality of Perugia, has the goal to define a tool for monitoring the quality of road markings and for reducing the costs of maintenance. In particular the objectives of the measure are:To develop a methodology to verify the efficiency of road pavement markings depending on installation conditions and available technologies.To define a protocol to verify if contractors respect the requirements defined by the public administration.CIRIAF will undertake measurements in selected locations, representative of the whole municipality area of Perugia, in order to extend the results of the demonstrations to the whole city. There are many variables to take into account when optimizing horizontal pavement markings. The Municipality’s road network is crossed by high intensity traffic routes not only with over 1,000 vehicles per hour, but also by local streets with much lower traffic density. Thus measurements will be undertaken in places which can represent this wide range of conditions, in order to better evaluate the wear of materials over time.Street surfaces range from smooth pavements to cobblestones; selected locations for measurements will take into account all of the most representative surfaces which can be found throughout the city.A wide range of horizontal marking materials will be considered, both standard (paint, thermoplastic, two-components, preformed) and innovative; in order to compare their relative performance. Therefore the choice of measurement locations will be guided by the necessity to guarantee up-scaling of the results to the whole city. As a result of the wide range of road surface materials (from smooth asphalt to cobblestone), for signaling and traffic conditions which can be found across the city, the results will be easily transferrable to other places as well. In the highest part of town, the erosion effect of salt spread in the streets following snowfalls can be considered, making the results transferrable also to other cities with colder average temperatures in winter. Skid resistance measurements are performed using artificial wet conditions, thus weather doesn’t affect the tests and can thus be extended to any city.CIRIAF has already acquired all of the necessary equipment, and a first round of preliminary tests is being carried out, to define the correct ‘modus operandi’ to undertake the in situ measurements of road marking quality. In particular the three instruments that will be used by CIRIAF are:A Retro-reflectometer is used in the testing. This instrument measures the night visibility (RL) of road markings, as seen by a vehicle driver driving with dipped headlights. The illumination simulates the dipped headlights of a vehicle. The day visibility (Qd) of road markings under typical or average daylight, or under street lighting, is measured with diffused illumination. This provides an objective determination of night (RL) and day visibility (Qd) of road markings in accordance with EN 1436.A Skid Resistance Tester provides a measure of the friction between a skidding tyre (a rubber slider mounted at the end of a pendulum arm) and the wet road surface. The quantity measured with the portable tester has been termed Skid-resistance and this correlates with the performance of a vehicle with patterned tyres braking with locked wheels on a wet road at 50 km/h. A Spectrophotometer is a portable, hand-held instrument, designed to measure, match and control the colour of small, irregular surfaces, as well as sub-strata with specific grain, texture or directional characteristics. It will be used to measure the chromatic co-ordinates of road markings.
Author: Maciej Wiórek
