VÄDER I TRAFIKEN : EN UNDERSÖKNING OM HUR VÄDRET PÅVERKAR TRAFIKOLYCKOR I STOCKHOLMSOMRÅDET

This report discusses how the weather affects the traffic focusing on accidents due to various types of weather and in that case how the weather affects. In this report, weather is used to describe a temporary state of temperature, precipitation and wind at a certain location. The accidents due to the weather have been combined with a several parameters, for example light, level of injury and when the accidents happened to see if this had something to do with the result.Sweden strives for the so-called Zero-vision, which goal is that no one should die or get seriously injured in traffic. As a part of this the purpose of the report is to investigate the effects of weather and if it’s possible to prevent accidents due to weather.The report is built on literature studies, accident data from STRADA and an interview with Folksam. The data has primarily been used to sort out the accidents that seem to be due to weather and then all the accidents have been compared with the ones due to weather in various diagrams. Thereafter, all the different parameters for weather related accidents have been put into crosstabulations to find connections.The investigation is delimited to five municipalities within the Stockholm area in the timeframe of three years and only when cars were involved.From the investigation, I gather that the majority of the accidents are not related to the weather conditions, but rather to our human behaviour and attitude to the current weather. The weather when the accidents happen doesn’t seem to differ very much between all accidents and the ones related to weather. Neither does the level of injury differ. Time of year varies more, as weather related accidents primarily happen during the winter months, but all accidents in total are more divided over the year. The most common circumstances are that the road is slippery or that the driver is blinded by the sun. The most dangerous combination seems to be clear weather and shallow ice with visible road surface, but also rain and a wet road is the cause of many accidents.The literature already includes studies showing that speed and traffic flows decreases with slippery, snowy or icy road surface conditions and the studies also makes a difference between pre, mid and late winter period. Even in the summer the roads can become slippery through both road polishing and bleeding asphalt. In the literature it is also described what effect speed has as well as snow clearance measures. Problems with damaged windshields where scratches creates poor visibility as well as how bad eyesight of the driver reinforces this effect is also discussed.Finally, it is concluded that our behaviour as humans is the prime factor for the outcome of the accidents. How we behave in the presence of current weather and how well prepared we are for the risks which follows different weathers and circumstances will affect how well we can handle these situations