The Lapstone Zig Zag is in the Lower Blue Mountains suburb of Lapstone. The 1867 Knapsack Viaduct that forms part of it is signposted from the Emu Plains exit of the Great Western Hwy (M4). From the car park at the junction of the old highway (which used the viaduct for a while) and Mitchells Pass, a concrete path rises gently as it follows the zig zag to the viaduct and across it. From here, dirt paths (suitable for walking only) descend below the stone arches and up to Elizabeth Lookout

The highway took the alignment of the rest of the bottom leg of the zig zag, but it is possible to walk from the viaduct along the footpath next to the M4 to reach stairs to the middle “leg” of this engineering marvel. This neglected uphill section is still dirt and ballast.

The top section is more easily reached from a recently built trailhead at the eastern end of Knapsack St, which will take you down through some of the major cuttings on smooth asphalt and past the Lucasville Station site to the upgraded Top Points Lookout.

The 634 m Glenbrook Tunnel, which bypassed the awkward zig zag after only 25 years, is located mainly south of the curving Great Western Hwy. A second railway viaduct built to the east as part of that re-routing project is still in use in conjunction with a wider, two-track Glenbrook Tunnel. The first one was closed after only 21 years but may be recommissioned for cyclists and pedestrians. The upgraded track to the eastern portal of the old tunnel is further along Governors Drive, next to a water reservoir.