THE RED & THE GREEN.

Sun (Christchurch), Volume I, Issue 100, 3 June 1914, Page 3

THE RED & THE GREEN.

RAILWAY SIGNALLING.

WHANG-AMARINO INQUEST.

Prete Aj*tcimli»n. i AUCKLAND, June 2. - A practical of- semaphore signalling was made to-day for the informationof Mr F. V. Frazer, S.M., who is conducting the nquest re-'*' •garding the railway disaster on Wed- • nesday last. /C'ounsel for tnte various interested, persons were alsf present. The inquest 'will be resumed ,on June "and'*'. eyidence7'wifi' fthen ,be "given.'' that shortly after the actidertt the signal' iever - was. locked in the danger .position, but that-the signal waa green for "all cleat." / ?

Attention was given principally to, the- manner- in 1 which • -the semaphore operates at night; There .is , OKly- one •signal south .of and it was upon ' this that the driver of the. express- train? had -to. rely in ap'prdaeh ing the staticra..,The length of; the traeis between the* centre of the - station piatforin' arid" the signal is 604 yards, and the signal is fixed,, at; 30ft. above the rail level on a post 35ft from the centre of tlie track. The signal stands ,at' the.. ljrie. rises, the'signal/and', curves, into. a_ descending, gradient ..to-' wards ,, In the position selected ifor. it the signal is visible from .the preceding mile or'track. - - The -aetual , length of the wire- connection between the lever and signal, including shiort pieces of <;hain passed, round, grooved pulleys to change 'the direction .of thP wire,, is. about ten yafds greater, .so that the connection is formed by about 614 yards of .steel wire, seven-eighths, of yan inch iii .ciT;' direct; ;dist«ncb "frbin the:signalJeyei ..to. the points switch at which the tablet porter/ -William Donaldson,- was engaged When :the,"disaster* occurred, • is nearly 56ft. The semaphore signal, consists. otf an arm or .blade/which is puileddbwn or '' off " to ■indicate that - the train- may - pass> ..atid in tHe horizontal or "on" position in--dicating '.'stop.;'' ; " 4 . Fixed to the runner end„of the blade' is a frame, Containing red' and J green glasses, which ihoyes with? the blade before a lamp,,so that ,at ; night. red is ? shown for <J danger ?/ and green for 'go ahead" or •"allclear. •' / The -• frame holding coloured glap'ses.. is, .'roughly, kidney-shaped,-and 'the device is known as the 1 'spectacle.Though " the : in-. tttgryal glasses rpw strip of-metal forining part pf, Ihe. frame, moveinen't of. tHe'seiria"-'. phpre* will f give ; the " fullgreen' Signal which/ iii darkness, jobscuriug the indin •cation' of appearex4ctly the ;same ; if- the signal had been inoved. i Tfie maximum distance experiment has shown that tlie draw required - at the ""lever tb'<lepress fully, tlie semaphore of •. the. ' Wliangaiha'rinb signal is 11 inches, but only seven inches, at the foot of the post. ;made ' at' ■ festerday's ; demonstration - allowed. • that ,a draw of onfy three inches inbyed the '/spectacle enough to; show the/full green. { "J' '' : 4 '- , The red or green.-'signal is not "visible tb the officer operating the, signal. - His .only- guide -to the position of' signal is a Ismail white' light:,-shining :;tKro,ughthe back pf the lamp. Part of, the ap-' paratus is an . iron Shutter, whieh/moving with ■ the '' spectacle;' bbscures this white light. ' The latter -is visible.' only wKen the semaphore is horizontal, • and the signal-showing full redJ ve'iy ; slight movement.,.of the central axis moves the shutter sufficiently ' to obscure -the white light completely," and when the: signal is beinglpxdled'- f.f 'offl'.-. at night the white light disappears long before the gree.n shows from the other 'side., v '' ' ' ' .;■■

There is a well-known rule that the absence, of a signal where a' signal is ordinarily shown must be treated as ; a danger signal, and where a.-signalman cannot perceive the white light of a signal which should be at danger, it becomes -his duty to ascertain whether the lamp, is extinguished or the signal out of order. , ■ -

The obscuring of the white light by a fractional movement of the signal is designed as a guard against an improper display of the ( ' all jelear '.' signal, and is complete long before the . full green shows. , There is an electrical device known as a " repeater," which is employed in connectidnvwith signals that are beyond, the range of the signalman 's vision. Its indicators change from "danger",' to < < clear ". only when the semaphore lias been completely depressed, • and the '1 danger 'indicator isrestored by the least upward movement of the, arm. This device was not in use at Whangamarino.