In areas with steep topography, protect ridge lines and avoid large scars in the landscape by using underpasses or short tunnels.
Benefits
- Allows alignments to better respond to local landscape character
- May provide improved vertical alignment
- Retains connectivity at the surface above
Considerations
- May involve complex engineering to be feasible in certain geology
- Treatments over a certain length will be treated as tunnels and need lighting, ventilation and additional ongoing management
Reference
TfNSW Guide
TS 01592 Beyond the Pavement, Principle four
Examples
The Tintenbar to Ewingsdale upgrade on the Pacific Highway uses a short tunnel to avoid a cutting, keeping the natural ridge line intact. This has preserved the existing landscape character, views and connectivity along the ridge. The tunnel portals are well-designed, and the contours around the site have been carefully graded to integrate with the surrounding landscape.
Location:
Pacific Highway, St Helena near Byron Bay
Agency responsible:
TfNSW
The historic axis of Leura Mall, running along a dominant ridge line, runs perpendicular to the Great Western Highway. To upgrade the highway, while preserving the character of the Mall and its relationship to the surrounding landscape, we constructed a 125-m long underpass with a high-quality of architectural design. Access for all modes is via ramps which wrap neatly into a portal.
Location:
Great Western Highway, Leura
Agency responsible:
TfNSW
Application
| Local streets | Main streets | ||
|---|---|---|---|
| Residential lane |  | Destination high street | |
| Residential way | | Transit street | |
| Yield street | | Connector avenue | |
| Neighbourhood street | | Arterial high street | |
| Connector street | | Transit arterial | |
| Urban centre street | | ||
| Enterprise street | | ||
| Main roads | Civic spaces | ||
|---|---|---|---|
| Transit only corridor | | Civic high street | |
| Rural link | | Transit mall | |
| Rural highway |  | Civic lane | |
| Secondary arterial | | Service lane | |
| Principal arterial | | ||
| Motorway | | ||
Legend
| Appropriate treatment |
 | Use with caution |
| Inappropriate treatment |
 | Not applicable |