The A909 has gained a few miles at the expense of its neighbours, due to construction of first the M90, then the A92 improvements. The most scenic way to drive it is north to south.
The A909 emerges seamlessly from the B914 at Junction 4 of the M90. There is a magnificent dead-straight descent through the town, with several speed bumps. This section was all B914 prior to the motorway, and was elevated to A status as a feeder from much of southern Fife into the northbound M90. In the town centre the dead-straight B917 Hill of Beath–Kinross crosses (why was the A90 not routed this way?). East of Kelty is an acute TOTSO with the B996 (it looks worse on the map than on the ground), the straight route being the former A90. A very twisty section of former A90 continues to the outskirts of Cowdenbeath where the B981 (once A910) joins at a roundabout.
Descending into Cowdenbeath, the A909 passes under the Fife Circle railway line en route through the centre of this depressing town. A roundabout at the southern end marks the 1922 start of the road as the B981 heads off to the right, and a very busy stretch of road leads to the diamond where the A92 is crossed by an overbridge. A realigned section with eased gradients follows, passing the sci-fi retorts of the Fife Polyethylene Plant, to reach a roundabout with the B925 Halbeath–Kirkcaldy. The A909 multiplexed with the A907 here for many years from the mid-1920s but that road has now been downgraded east of the M90. A twisting switchback section follows; in one place the modern road seems on a map to cross over a former alignment by a bridge, but this isn't evident when driving.
The road to Burntisland
Midway is a strange double TOTSO with the B9157, explained by the fact that the crossing road (previously the A907 to the east and an earlier incarnation of the B924 to the west) was once the main route from Kirkcaldy to the Firth of Forth road crossing before the A92 was rebuilt on its present alignment. Back on its original line, the A909 sweeps down into Burntisland, with magnificent views across the Firth of Forth, to end at a roundabout with the A921 (once A92). The A909 originally continued along the decrepit High Street to the harbour after a short multiplex with what was the A92 and is now the A921, to meet the ferry to Granton and the A901 and A903. This final section is still shown on OS 1:10000 maps from the 1980s, but was probably downgraded soon after; it is now unclassified.