Q 144
The Survey Office commenced levelling along this route, accepting as a preliminary measure, the existing Datum of Kowloon Levels as given by the Drainage Office value for "Staple B.M. No. 36".
The levelling of the circuit round the N.T. was not of a Primary Order; the final closing error from the preliminary work of a 50 miles circuit when double levelled was 0.119 feet or P.E. per mile of .016.
Each line between milestones was double levelled, i.e. once in a forward direction and once back. If the discrepancy between these two levellings exceeded 0.015 feet, the operation was repeated.
During the levelling, the Survey Office fixed and levelled to 9 Fundamental Bench Marks on the route at an average distance of 6 miles apart. These F.B.Ms. consisted of a brass rod at least 1 foot in length let into rock, bedded in cement and covered by a picket box. They were placed at the following points:-
Cosmopolitan Dock at Tai Kok Tsui, Water Works Pass Summit, Sha-Tin, Taipo, Fan Ling Railway Station, Au Tau, Castle Peak, Sum Tseung, and Tsin Wan.
Also, 2 Staple Bench Marks were fixed at Taipo Market and Castle Peak P.W.D. Quarry Depot.
In addition to the above 9 F.B.Ms. and 2 Staple B.Ms., the following Trigs were levelled to:-
Trig. No. 65 Tide Cove, No. 71 Taipo, No. 76 between Taipo Market and Fanling, No. 4 Fan Ling, No. 85 Au Tau, No. 90 Shek Po, and No. 92 Lam Ti.
Certain road bridges were levelled to, including:-
Shing Mun River Bridge at Shatin, Ma Miu Shui Bridge, Taipo Bridge, Taipo Market Bridge, Au Tau Creek, Un Loong Bridge, Tai Lam Chung Bridge, Sum Tseung Bridge, Tsin Wan Bridge, and also Castle Peak Pier Decking.
Various Railway Bridges at Taipo and Fan Ling were levelled.
10. With regard to figures cut as Railway B.M. values on the K.C.R bridges from Fan Ling to Shatin, these figures were found to give a value approx. 1 foot too little when compared with the value obtained by levelling from the Datum of Kowloon Levels given by the Drainage Office value for Staple B.M. No. 36.
This anomaly is explained by the fact that the figures on the railway bridges were cut before the railway was connected up through Shatin Tunnel to Kowloon Datum.
Q 144
The Survey Office commenced levelling along this route. accepting as a preliminary measure, the existing Datum of Kowloon Levels as given by the Drainage Office value for "Staple B.M. No. 36".
The levelling of the circuit round the N.T. was not of a Primary Order, the final closing error from the preliminary work of a 50 miles circuit when double levelled was 0.119 feet or P.E. per mile of .016.
Each line between milestones was double levelled i.e. once in a forward direction and once back. If the discrepancy be- tween these two levellings exceeded 0.015 feet the operation was repeated.
During the levelling the Survey Office fixed and levelled to 9 Fundamental Bench Marks on the route at an average distance of 6 miles apart. These F.B.Ms. consisted of a brass rod at least 1 foot in length let into rock bedded in cement and covered by a picket box. They were placed at the following points:-
Cosmopolitan Dock at Tai Kok Tsui, Water Works
Pass Summit, Sha-Tin, Taipo, Fan Ling Railway Station, Au Tau, Castle Peak, Sum Tseung and Tsin Wan.
Also 2 Staple Bench Marks were fixed at Taipo Market and Castle Peak P.W.D. Quarry Depot.
In addition to the above 9 F.B.Ms. and 2 Staple B.Ms. the following Trigs, were levelled to:-
Trig. No. 65 Tide Cove, No. 71 Taipo, No. 76 between Taipo Market and Fanling, No. 4 Fan Ling, No. 85 Au Tau, No. 90 Shek Po and No. 92 Lam Ti.
Certain road bridges were levelled to, including:-
Shing Mun River Bridge at Shatin, Ma Miu Shui Bridge, Taipo Bridge, Taipo Market Bridge, Au Tau Creek, Un Loong Bridge, Tai Lam Chung Bridge, Sum Tseung Bridge, Tsin Wan Bridge and also Castle Peak Pier Decking.
Various Railway Bridges at Taipo and Fan Ling were levelled 10. With regard to figures cut as Railway B.M. values on the K.C.R bridges from Fan Ling to Shatin, these figures were found to give a value approx. 1 foot too little when com- pared with the value obtained by levelling from the Datum of Kowloon Levels given by the Drainage Office value for Staple B.M. No. 36.
This anomaly is explained by the fact that the figures on the railway bridges were cut before the railway was connected up through Shatin Tunnel to Kowloon Datum.
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