[ D] In the European Union, transportation has become one of the major sources of pollution, especially air pollution. Hence, the question is how transport and mobility requirements can still be met with less carbon emissions. The focus of transport and mobility research at ZEW is on two aspects. First, we analyse the effects of a carbon emission trading system implemented in the transport sector. Second, we try to discover quality aspects in freight transport which have an influence other than the transport price on the modal choice decision of carriers and forwarders. The effects of different policy instruments on changes in transport behavior and, thus, on the carbon emissions can be quantified.