The aim of the Winter model is to estimate and put a value on the most important impacts of strategies and measures in winter road management for road users, road management authorities and society at large. A first version of the Winter model, with all its sub models, was published 2006 in VTI report 531 (The Winter model. Stage 2. Final report) http://urn.kb.se/resolve?urn=urn:nbn:se:vti:diva-6420. Because the level of ambition with the first version of the Winter model was to achieve a working prototype there are improvements to make within different areas or sub models. The improvements consist of actions with a wide variety of work from a few hours to several years of analysis, modelling and programming. The presentation of the project will begin with a list of important short- and long-term bug fixes and improvements to the Winter model and their rank (priority 1–3). The next chapter describes the implemented bug fixes and improvements with priority 1. The report is finished with a sensitivity analysis of the Winter model. Here the uncertainties in the various sub models are estimated. It is found that, in terms of socio- economic total costs, the uncertainties in accident risk and consequences of accidents have greatest influence. Since the purpose of the Winter model is to compare different strategies and actions the socio-economic total costs are not of the most interest. Instead the difference in socio-economic costs between alternatives, that is what benefit is gained from the changes in strategy or action, is of interest. Such a marginal cost analysis has been done with data from the calculation of socio-economic total costs. Here, the benefit can be estimated of more salting which will decrease the proportion of snow and ice on the road and increase the proportion of bare ground. It turns out that the most important components of the socio-economic marginal costs are the reduction in accident costs and secondly the reduction in travel costs.