Central Junction Railway
| Central Junction Railway | |
|---|---|
| Overview | |
| Native name | 中繼道 |
| Termini | South Bridge Tlang-qrum Station |
| Stations | 1 (Twa-ts'uk-men) |
| Operation | |
| Opened | 30 September 1897 |
| Completed | 27 September 1897 |
| Operator(s) | Railways Themiclesia |
| Events | |
| Closed (war) | 1940 |
| Re-opened | 1944 |
| Technical | |
| Line length | 7.1 km (4.4 mi) |
| Number of tracks | 4 |
| Track gauge | 4 ft 8 1⁄2 in (1,435 mm) standard gauge |
| Minimum radius | 85 m (inside) |
| Operating speed | 40 km/h (25 mph) |
The Central Junction Railway (Shinasthana: 中繼道, trung-kits-luq; lit. "central continuation road") is a 7.1 km railway that bridges the end of the Traverse Main Line with the Inland Main Line. Except its termini, it serves only one station, Twa-ts'uk-men Station. The railway consists of a two parallel tunnels with double tracks and ramps on the west end, while joining the Inland Main Line in the Great East Junction, which itself is underground.
The Central Junction was built some four decades after the earliest main line railways arrived at the capital city of Kien-k'ang, which did not meet each other but terminated at the city's fringes. To enable trains to run through from one railway directly to another and enable railway passengers to alight at city centre, the Central Junction was planned in 1891 and completed in 1897. An underground construction was necessary to cut through the city, which barred the construction of level crossings at several important places in 1877.
History
Route
Issues
Geometry
The CJR is defined by its consecutive tight curves, which in turn mean restrictive line speeds; since the time the railway opened in 1897, the line speed has barely improved, being 35 km/h or 20 MPH.
These tight curves arose out of the imperative to build mostly under existing public roads that are wide enough for the tunnels; that policy was feasible thanks to late-19th-century city boulevard, which were deemed to make streetscapes more upscale and desirables. This avoided unaffordable mass demolition of buildings for the most part but still necessitated the widening of two sections of road to accommodate the parallel tunnels and their retaining walls, which came to a combined width of about 21 m.
On the inside track under the Acorn Road turning into Avenue, the curve originally measured but 73.5 m, though inside tracks have since been marginally improved to a curvature approaching that of outside tracks. However, any significant improvement would effectively mean rebuilding the tunnel completely, obliterating buildings that have appreciated many times in value since the end of the 19th century. Since 1952, the recommended minimum radius on curves on main lines has been 360 m, though the sharpest on the CJR remains at 90 m, while it is considered a main line.
Shallowness
The tunnels were built approxiately 6 m deep, measuring from the top of rails to surface; elements of the subgrade and drainage are up to 8 m deep. On the one hand, shallow tunnels mean ramps are shorter with the same grade and are much cheaper to build by the conventional cut-and-cover method. On the other hand, it means there is little to distribute loads across the roof of the tunnel, and so the road above the tunnel has limited loads. This was made painfully apparent when a column of tanks crashed into the tunnels on Jun. 17, 1945 as section gave way after section, killing 17 and injuring 40.