The Lake District is very nearly contained within a box of trunk routes and major A roads. It is flanked to the east by the A6 road, which runs from Kendal to Penrith (though the National Park extension approved in 2015 is east of the A6); across its southern fringes by the A590, which connects the M6 to Barrow-in-Furness, and the A5092; and across its northern edge by the A66 trunk road between Penrith and Workington. The A595 (linking the A66 with the A5092) forms the park boundary from Calder Bridge to Holmrook, then crosses the coastal plain of the park until turning inland at the Whicham Valley, forming much of the park boundary again until joining the A5092 at Grizebeck.