Urban congestion that is known to provoke a high level of green house gas emission and fuel consumption is mainly due to car use and especially for go to work travels. Decision makers are willing to reduce the car pressure and they describe a set of possible action in urban travel plans. One solution is to plan the realization of right of way systems in order to enhance public transport (PT) performance. In our presentation we simulate the introduction of a new tramway line on the former coal mining area in the Nord-Pas-de-Calais region in the northern part of France where two tramway projects are scheduled. We determine a basis scenario model linked with the introduction of one of these new tramway lines around the city of Lens. We use the 2006 census data for commuters from INSEE the French national statistics institute. Based on this scenario we calculate the different flows for the PT users and for car drivers and the congestion effects that affect the costs and transport times. This allows us to determine the generalized costs of transport for PT users and for car drivers that gives an explanation on the different usages. Transport public policies, as public interventions are after set up in order to evaluate if they are able to change transport behaviour for these commuters on our study area. A set of different public policies have been sorted out and tested such as measures to enhance the PT use for instance deciding free access to PT or measures that increase the cost of car trips for example introducing a tool on the motorway, taxing the parking in the inner centre of the three main towns or raising the price of fuel. We then are able to calculate the ecological impacts of these measures that give elements for the transport public policies evaluation.
