In the years ahead, one of the most important tasks of the government of the Russian Federation is to bring the condition of highways of various categories to standard parameters and ensure their safety. This is reflected in the decrees of the President of the Russian Federation and in national projects, for example, in the national project on “Safe and High-Quality Roads”. In order to ensure safety and reduce damage from road traffic accidents on highways, various measures are used, including the installation of technical means of road traffic organization. These measures include cable barriers, which also have become popular recently. According to numerous studies, this kind of barrier has a positive effect on the passive safety of highways and it reduces the number of accidents with serious consequences that occur as a result of vehicles driving in the oncoming lane. However, the incorrect installation of these barriers (non-compliance with the minimum safety lanes at barriers, improper installation of barriers when the number of traffic lanes changes, etc.) and imperfection of the modern regulatory framework can negatively affect both a driver and the traffic flow in general, leading to the increase in the number of road traffic transport accidents. This is explained by the fact that a driver of a car, being afraid of close movement along the cable barriers at high speed, tries to stay away from the barrier as far as possible, increasing the side clearance between the vehicle and the barrier. However, at the same time, the side clearance between vehicles passing in the right lane (where a driver has limited visibility) or any obstacle on the right (for example, cars standing on the side of the road) sharply decreases. The article considers the results of the study of changes in the side clearance between the centre line of a road in the presence of a cable barrier and in its absence. The measurement results were compared. According to the results of the measurements, the authors gave the recommendations to improve road conditions, safety and the recommendations for further study of this issue.