Roads and infrastructure strongly influenced on the environment. Therefore an effect of road network on hydrological conditions of watershed should be taken into account. Road networks have an effect on surface water flow and lead to direct and indirect changes of water circulation in the environment. Road networks appear to have increased contribution of impermeable areas and decreased infiltration and retention capabilities. This effect in increasing of flood waves peak and also expedite time to their occurrence. During storms or snow melting junctions of road and stream networks could be additional sources of water flowing directly from road surface or from ditch to the stream. In the paper we describe method which could help to find areas with high interaction between road networks and stream networks. Examined area of Kleszczewo community was divided into grid which consist of 92 square cells of 1 km side size. For each cell we described the interaction of road and stream networks. The generalized factor take into account density of stream network, density of road network, number of junctions of both networks and length of roads closer than 100 m from streams in each cell. Calculated values of the factor allow to distinct three classes of interaction possibilities. Results of investigation showed that the community area has big density of stream network, as well as road network what effect in numerous junction points. The majority of junctions occur between streams and field roads. Analyzed area show great variability in possibility of interaction between road network and stream network occurrence. Areas with highest possibility of such interaction took almost 25% of total area. Such places could effect in higher direct storm water flow into streams, and in consequence higher flood peaks.