Re: Engineering question- Alpine Tunnel
| April 16, 2017 06:05PM |
|
Yes it is strictly to do with drainage, whether depending on the catchment area and flooding susceptibility considerations.
We have 4 very long (NG
) tunnels, 3 of which are in the North Island, two of those being located in my old running district.
Kaimai 29,035 ft, gradient of 1 in 323, Apex at Western Portal above flood stage, never worked under steam. Longest in Southern Hemisphere.
Rimutaka 28,865 ft, gradient of 1 in 400(from West Portal) and 1 in 180(from East Portal) ventilation shaft at central apex, never worked under steam. Headings were out by 1.75".
Otira (on Sth Is) 27,735 ft, with continuous 1 in 33 grade, top grade Portal above flood stage. Force ventilated, formerly electrified without ventilation, never worked under steam.. Driven from both ends, headings were out by 1.125" level and .75" alignment. [wondersofworldengineering.com]
Tawa No.2 14,183 ft with a 1 in 122 gradient, (Tawa No.1, 4,062 ft 1 in 110 gradient), double tracked, steam worked initially then electrified, later Diesel. Apex at Northern Portal above flood stage.
We have 4 very long (NG
) tunnels, 3 of which are in the North Island, two of those being located in my old running district. Kaimai 29,035 ft, gradient of 1 in 323, Apex at Western Portal above flood stage, never worked under steam. Longest in Southern Hemisphere.
Rimutaka 28,865 ft, gradient of 1 in 400(from West Portal) and 1 in 180(from East Portal) ventilation shaft at central apex, never worked under steam. Headings were out by 1.75".
Otira (on Sth Is) 27,735 ft, with continuous 1 in 33 grade, top grade Portal above flood stage. Force ventilated, formerly electrified without ventilation, never worked under steam.. Driven from both ends, headings were out by 1.125" level and .75" alignment. [wondersofworldengineering.com]
Tawa No.2 14,183 ft with a 1 in 122 gradient, (Tawa No.1, 4,062 ft 1 in 110 gradient), double tracked, steam worked initially then electrified, later Diesel. Apex at Northern Portal above flood stage.
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488 stops for water at Los Pinos tank on closing day Oct. 1979. Photo courtesy Don Richter
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