The evolution of transport in Cornwall has been shaped by the county's strong maritime, mining and industrial traditions and much of the transport infrastructure reflects this heritage. However, with the decline in mining and industry over the last century and more, transport provision in Cornwall has increasingly focused on the needs of tourism and holiday-makers. An example of this is the improvement of the A30 trunk road; the substantial dual carriageway sections have greatly relieved summer traffic congestion but are very under-used in winter.