INTERMODALITY AND LOGISTICS In the midst of growing sustainability concerns, transport systems pose a range of environmental problems. ✓ This is especially so for road transport, which has been increasing its share of transport relative to other modes. ✓ These problems include noise and air pollution caused by traffic congestion and the increase in CO2 and other vehicle emissions. ✓ In particular, heavy vehicles used in freight transport are considered to be the main source of these problems.