Retroreflection of traffic signing for the safe operation of agricultural machinery

Recent studies have discussed the increasing number of accidents caused by agricultural machinery and tractors, specifically on higher-class roads. High-quality traffic signage with the required retroreflection can prevent these serious accidents, especially under reduced visibility conditions. The retroreflective materials are divided into three classes: RA1, RA2 and RA3 according to their optical performance. This distribution apparently turned out to be insufficient, as significantly different optical materials may be assigned to the same class. This research focused on the detailed optical resolution of retroreflecting sheeting with the aim to support enhancement of the current standards. The coefficient of retroreflection (CR) was measured under standard requirements. It was concluded that the combination of 3M 3930 sheeting (CR = 7.81) and 3M 4090 (CR = 9.03) sheeting is not recommended, as the difference between these values and the other monitored samples is significantly higher than CR = 2. Especially with the introduction of autonomous mobility, the recognition of signs will also have fundamental effects on agricultural technologies, where elements of independent mobility will be gradually introduced.