On 7 January 2005, the A818 number was recycled to take over the B831 and the southern part of the B832 between the A82 by Loch Lomond and Helensburgh. This was always the preferred route into Helensburgh, avoiding the slow signposted route via the A814 through Dumbarton - and the new A818 has seen much improvement in recent years, including the construction of a cycle route alongside the road from the A82 to the edge of the town.
Arden - Helensburgh
Looking uphill from the second Fruin Bridge towards the roundabout
Starting at the Arden Roundabout on the A82, the A818 heads west along the former route of the B831. This first section of the route is fairly straight and level as it crosses the farmland either side of the Fruin Water, with the road climbing a little on the west side of the bridge. After a mile or so, the road reaches another roundabout, at Cross Keys, where it meets the B832 which doubles back to Loch Lomond. The A818 turns left here onto the former route of the B832, while straight ahead is the minor road through Glen Fruin that has been largely replaced as a through route by the A817 on the hillside high above.
From the roundabout, the road drops down to cross the Fruin Water again, then climbs steadily through fields and forestry to meet the summit on open moorland at over 100m. Just before the summit, a minor road turns north to meet the old Glen Fruin Road. No sooner has the road has crossed the hill, when it starts to descend into Helensburgh, the highest properties sitting around 100m above the shore far below. At the entrance to the town, a side road on the right is signposted to Hill House, one of Charles Rennie Mackintosh's most famous buildings and now owned by the National Trust for Scotland. The road then continues straight downhill, passing over the West Highland Railway line and down through the leafy streets of the town. The bustling town centre lies mostly to the right, set around a spacious square and soon after the A818 comes to an end, meeting the A814 on West Clyde Street, almost opposite the pier.