Rathole tunnel

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Rathole tunnels are railway tunnels where fumes from locomotives make passage through the tunnel unpleasant[citation needed].

Contents

[edit] Overview

Rathole tunnels are characterized by being long, steeply graded, narrow bores (often with single tracks). Their locations may also be subject to unfavorable winds that prevent smoke from clearing the tunnel.

Some of these features are caused by the tunnels having to be unusual shapes (such as incorporating an S shaped bend in the middle), or changing gradient in the middle.

[edit] Examples of Rathole Tunnels

[edit] Australia

  • Ardglen Tunnel in New South Wales - Garratt locomotives prohibited, because of heat problems in the narrow bore.
  • Coalcliff Tunnel in New South Wales - restricted loads for heavy 57 class engines, so that engine need not work at full blast.
  • The old Otford Tunnel, Otford, New South Wales - notorious for suffocating fumes - at ruling 1 in 40 grade - sea breezes often blew smoke along with train. c1880.
  • The old Lapstone Tunnel that replaced the Lapstone Zig Zag was built too steep and eventually had to be replaced by a gentler alignment.
  • Bylong Tunnel - air intakes for diesel locomotives had to be redesigned to prevent air starvation to the second and third locomotives.
  • The 10 tunnels at Lithgow that replaced the Zig Zag Railway were sometimes considered to be rathole tunnels, but the gradients were fairly gentle at 1 in 90 (1.11%), the tunnels were double track, and the gaps between the tunnels allowed for some intermediate ventilation. The western approaches were graded at 1 in 42 and required use of Bank engine helpers only in the open air. This deviation was opened in 1910.
  • The long tunnel on the Ulan line in New South Wales has a tight profile and train crew must be supplied with respirators before entering the tunnel.
  • The Rhyndaston Tunnel in Tasmania is 955 m long with a small bore, and is graded at 1 in 40.

[edit] Germany

  • Cochemer Tunnel, 4205 m long double-track, opened 1877; ventilation system 'Saccardo' installed in 1904, ventilation shaft added in 1913, electrification 1976

[edit] Italy

  • In the Balvano train disaster of March 3, 1944, over 500 people who stole a ride on a steam-hauled freight train died of carbon monoxide poisoning when the overloaded train stalled in a steeply graded tunnel.

[edit] United Kingdom

[edit] Switzerland

  • Ricken-Tunnel, 8604 m long single-track, gradient 15,75 ‰, on October 4, 1926 9 railwaymen died of carbon monoxide poisoning while their train came to a halt in the tunnel, electrified 1927

[edit] United States

  • The first Cascade Tunnel was built to replace an unsatisfactory quick-to-build section of line with 8 switchbacks, problems with snow, steep grades, train length limits. Unfortunately, the first tunnel was quite long (4.228 km) and had a steep gradient of 1.7%, and had severe problems with smoke, qualifying it as a rathole tunnel.
  • The second longer Cascade Tunnel 12.543 km long was built with gradient of 1.565%. It was originally electrified. However when dieselisation came, the fume problem resurfaced, requiring a ventilation system to be installed to clear the air after each train.
  • Winston Tunnel on the Chicago Great Western main line in northwest Illinois, with approx .95% grade. Despite being less than 1/2 mile long, the poor design of the tunnel meant that fan ventilation was required during the period that steam locomotives operated through it.

[edit] Rathole Tunnels Without Problems

  • Box Tunnel on the Great Western Railway, built ca. 1838 was never a problem, even though it is quite long at about 2 km, and has a relatively steep gradient of 1 in 100, because:
    • It is double track;
    • Its dimensions are large compared to the rolling stock gauge of the trains, since the route's conversion from Broad Gauge in the 1890s (note though that the monumental portals were an act of propaganda when it was built; the tunnel narrows to the proper size inside)
    • There are several air vents along the way (though this is normally the case when tunnels are constructed, there was worry of asphyxiation in the tunnel when it opened so excess were provided)
    • trains rarely enter tunnel from standing start (due to the closure of Box railway station)
    • double headed trains are rare.

[edit] See also