| Cowan Bank | |
| Line: | Main North line |
| Coordinates: | -33.5676°N 151.1992°W |
| System: | Sydney Trains |
| Start: | Cowan station (south) |
| End: | Hawkesbury River station (north) |
| Owner: | Transport Asset Holding Entity |
| Length: | 5 tunnels (1 since disused) of varying lengths |
| Tracklength: | 8.6km (05.3miles) |
| Notrack: | 2 |
| El: | 1959 |
| Lowelevation: | Sea level |
| Grade: | 1:40 |
Cowan Bank is an 8.60NaN0 double-track section of the standard gauge Main North line in New South Wales, Australia. It starts at Cowan station, 48.8km (30.3miles) north of Sydney, descending from 200m (700feet) to sea level at Hawkesbury River station. It has an average grade of 2.5% (1 in 40).
Cowan Bank has five tunnels (of which four are still in use), one level crossing (for track work road vehicles only) situated between Boronia #2 and #3 tunnels, and two road bridges. The line crosses under the Pacific Highway twice, once using a road bridge near Cowan station and again while passing through Boronia #1 tunnel. It crosses under the Sydney-Newcastle Freeway while passing through Boronia #2 tunnel. The line was built through very rugged and heavily forested terrain on the western edge of the Ku-ring-gai Chase National Park. Because of its isolated location there are very few places from where the track can be observed - sections of the Pacific Highway on the ridge between Cowan and the Hawkesbury River provide a few vantage points.
Bank engines were attached to the rear of trains at Hawkesbury River station to assist them in the climb and were detached at Cowan station. After assisting a train up the bank, the bank engine would usually return to Hawkesbury River station to await the next train. Bank engines are no longer used on the line.
Because of its long grade and proximity to locomotive manufacturing and maintenance facilities in both Sydney and Newcastle, Cowan Bank is often used to test locomotives and power cars.
The single track line between Cowan and Hawkesbury River stations was completed in 1887. Five tunnels (Boronia #1 to Boronia #5) were built as double track tunnels but initially only a single track was laid through them. The line was duplicated in stages between 1907 and 1909. The duplication work required major rock excavations as the permanent way was set back further into the hillside. This excellent sandstone fill was put to good use by realigning the track to ease four of the sharp 11 chain curves to standard 12 chain curves, resulting in Boronia #5 tunnel being bypassed and abandoned.[1] [2] [3]
In 1912, a relief line was opened between the #2 and #3 tunnels, but the steep grade caused numerous problems including stalled trains, damaged engines and breakaways, and it was soon relegated to storage for disabled trains or portions of trains. The relief line was finally removed in 1934, thus providing room on the formation for further improvements to the alignment for the two main lines some years later.[2]
The track loading gauge (maximum allowed width of carriages) has been progressively increased, with subsequent widening of the tunnels, between 1910 and 1973. The line was electrified in 1959.[1]
Bi-directional running was introduced in October 1996 to allow faster up trains to use the adjacent down track to overtake slower freight trains climbing the bank. Track cross-overs were installed at Cowan railway station, between Boronia #1 and #2 tunnels, and just south of Hawkesbury River railway station.[4] [5]
Five serious incidents have occurred to date on Cowan Bank: