摘要:AbstractThis paper deals with operating speed and hazardousness on two-lane roads and will define the characteristics (components) of driving environments (scenarios) used in an analysis procedure developed by authors in a Decision Support System (DSS). DSS aims to identify infrastructure projects, given a total cost, suitable to produce maximum reduction of social cost of crashes. Results obtained are the improvement of the V85formula and the trend of the Crash Index as a function of flow/capacity ratio in limited access two-lane roads. Both results show that limited access roads and at grade intersections roads must be handled as different scenarios.