A new technical specification of the "Road Infrastructure" Agency, which entered into force in 2025, removes a key ban and allows the use of limestone and dolomite in the top wear layer of asphalt pavements. The change raises serious concerns about traffic safety, as sedimentary rocks have lower wear resistance than the recommended igneous rocks,"Sega" writes.
World practice requires the use of igneous rocks such as granite, syenite, diorite and gabbro in the top wear layer due to their high strength and wear resistance. Limestone and dolomite are easily worn materials that should not be used alone for a wearing course under heavy traffic.
The change comes just as major road construction is looming in Northern Bulgaria, where limestone is abundant. The cheap material and the proximity of quarries to the routes make its use attractive to contractors, despite the safety risks.
Especially striking is the case of the award of the repair of 25 kilometers of the I-5 Ruse - Veliko Tarnovo road for a value of 35.8 million leva, which should be completed by the end of this year. With very heavy traffic with heavy goods vehicles and work without stopping traffic, the most likely scenario is that the wearing course with limestone will be polished before it is put into normal operation.
Wearing and "smoothing" on a road with a wearing course of sedimentary rock becomes a fact immediately after the first year of operation. In wet weather, the dust adhering to the pavement, together with the remnants of the worn rubber, forms a film that sharply reduces the grip between the tire and the pavement.
"Experienced drivers instinctively sense this moment and reduce speed, but such areas are often entered suddenly", explains the analysis. When investigating the case, the blame is usually shifted to the driver, who is driving at "inappropriate" speed, but the reason lies in the quality of the pavement.
The statistics of the Ministry of Internal Affairs show that all the blame for road accidents is shifted to drivers. For the last three years, almost all serious accidents have been classified as "the driver's fault" - in 2022, out of 6,609 serious accidents, only 6 were "the road's fault", in 2023 again 6 out of 6993.
There are three factors for traffic - man, road and car. It is unrealistic to blame only one of them, especially given that a large part of the roads in Bulgaria are in poor condition.
Experts insist that Bulgaria introduce requirements for the type of road surface depending on the intensity of traffic, altitude, number of days in winter conditions and other factors. It is also necessary to introduce the concept of "protective layer" - a layer up to 4 centimeters thick, which protects the road surface and is subject to periodic restoration.
The technical specification must immediately restore the ban on the independent use of sedimentary rocks in the wearing course during heavy and very heavy traffic. It is also important to introduce uniform requirements for the transport condition of the republican roads with technically justified criteria for maximum permissible damage, level of evenness and minimum coefficient of adhesion.