For current winter road maintenance, the determining of the salt dosing (spreading density) is mostly carried out by field personnel on the vehicles. From the evaluation of automated data logging, it is known that personal experience plays a key role in this process. This can be seen from the fact that comparisons of dosing by several employees reveal differences from the average set dosing of up to 100% under comparable boundary conditions. The pilot project "Optimisation of the degree of spreading material – Model to determine the spreading density objectively required in winter road clearance" commissioned by the Bundesanstalt für Straßenwesen (Federal Highway Research Institute), based in Bergisch Gladbach, Germany, set out to minimise the "subjective factors" involved in the application of ice-melting materials. For this purpose, four motorway maintenance vehicles in Brandenburg and North Rhine-Westphalia were equipped with on-board computers to process short-term weather forecast data (3 hour time horizon), road surface temperature readings and data from the road weather stations located along the route. The on-board computers are linked up with a central server via the GSM network, enabling continual updating of the weather forecast data. The algorithm software in the on-board computers calculates the optimal amount of spreading material based on liquid quantities forecast on the road surface and the road surface temperatures expected. In addition, the algorithm provides the option of determining increases and reductions for specific sections of the route. In this manner, the experience gained in previous winter service periods is also integrated into the calculation of the optimal spreading density. This can be beneficial on, say, bridges. Thanks to the GPS signal control, the optimal density setting ensues for the restricted section of the bridge crossing in good time without delay. The use of prognostic calculation of the spreading density has revealed a considerable potential for savings in the application of ice-melting material by means of this technology. This is particularly true in the case of preventative spreading operations. (Author/publisher)
Abstract