The need to improve the safety management in the maintenance and operational works on a motorway is a request that all the organizations demand to achieve better goals on safety and in the use of resources. The use of instruments linked to efficiency and effectiveness is one possible solution to this problem. The objective of the present investigation is to prove that it is possible to identify the main activities contained in the A area of an ABC curve and linked to the Pareto’s concepts, defining this way the 20% most dangerous maintenance and operational activities on motorway works. The methodology used was a DELPHI panel formed by experts from different areas linked to safety at work on motorways. The statistic treatment was made through the informatic program IBM SPSS Statistics 24. The results show that it is possible to identify 36 main activities in maintenance and operational works, being relevant the activities related to emergency response, safety guards, expansion joints, provisional signaling and the access to working stations in toll areas. The conclusions of the study reveal that these 36 activities represent the 20% most dangerous activities in maintenance and operational works on a motorway, and show that besides the risks of the work itself, there are four crucial traffic factors to develop a correct risk analysis: weather conditions, traffic characteristics, pavement characteristics and motorway morphologic type.