Good visibility of road furniture and particularly good visibility of road markings and traffic signs is not a question of prestige or luxury. It provides confidence for the driver and is thus a crucial factor in ensuring traffic safety.
Road authorities strive to maintain a very high standard thus they monitor and analyse the quality of their road furniture. A good quality control system and maintenance strategy is essential in order to preserve safety whilst it should not put an additional strain on the budget.
This can be achieved by means of various approaches. The easiest way is an automatic replacement of signs and markings at regular intervals. However, the operating life of road furniture depends on many factors including weathering, road utilisation, material, manufacturer and many more. Therefore, it cannot be predicted when a sign or a marking will lose its functionality and time-based replacement always bears the risk of wastefulness.
Another approach could be replacement after visual inspection. This simple strategy at least prevents the unnecessary renewal of still functional material. Nevertheless, it harbours the danger of subjective assessment. In most cases, visual inspections are carried out by persons who are very familiar with the area and the installed road furniture. Experience has proven that they will unconsciously give better ratings. So replacement by visual inspection may have the opposite effect as automatic replacement: signs and markings which are no longer sufficiently visible remain in use for too long and eventually become a safety risk.
The most effective and reliable procedure is a maintenance strategy based on measuring values and supported by a clever evaluation software.
Minimum requirements for the performance of road markings and signs are standardised in national and international standards as well as local regulations and thus offer an easy and objective assessment: with the help of measuring values it can be decided whether the sign or marking still meets the requirements and can be well seen by road users.
Also other important properties of the marking and its surroundings can be measured with new retroreflectometer models: the road levelling is important for the draining properties of the marking and an integrated camera can take on-the spot pictures of the marking from the perspective of the measuring geometry, delivering valuable information on glass bead distribution, soiling, abrasion and other factors
Taking measurements in the flow of traffic always bears a safety hazard. Consequently, ultra-fast measurements not only permit efficient procedures, but also increase the safety of the operator.
Long distance can be measured fast and reliably with mobile measuring systems, dynamic retroreflectometers. In the traffic flow, the vehicles travel at speeds of up to 150 km/h (93 mph) without impeding traffic. Measuring values are constantly recorded, photographed and can later be easily evaluated on a PC or laptop on a digital map or on a spreadsheet complete with the photographic record.
A smart evaluation and data management software will be a valuable tool to support this maintenance strategy. The retroreflection measurements of road markings, traffic signs and safety garments can be analysed to individual specification, and results are displayed on a map. For maximum compatibility with existing systems and procedures, measuring reports in several languages can be generated as pdf or xls files and data can be exported to external GIS.
This area-wide analysis method offers the advantage of a great overview of the marking condition and enables the systematic and intelligent application of maintenance management methods. The budget will only be used in areas where it is necessary and the quality of the marking, and with it also traffic safety, can be improved in the long run without spending more money.
Image: Zehntner’s retroreflectometers for all needs and budgets. Photo: courtesy of Zehntner.