SAFETY OF HARBOUR

Sun (Auckland), Volume III, Issue 840, 7 December 1929, Page 7

SAFETY OF HARBOUR

SHOAL BAY BRIDGE CONDEMNED HARBOURMASTER’S VIEWS Stating that it would interfere with navigation Captain H. H. Sergeant, Auckland harbourmaster, strongly opposed the proposal to erect a harbour bridge from Beaumont Street to Shoal Bay. Giving evidence before the Harbour Bridge Commission yesterday afternoon he favoured the erection of a bridge from Stoke's Point, Northcote, to Ponsonby. lie gave the requirements of a harbour bridge as 150 ft vertical clearance and 600 ft horizontal clearance. He considered that the Stoke's PointPonsonby route would interfere least with navigation. Although the line of the bridge he proposed would run from Northcote Point to about Shelly Beach Road by curving the bridge over the shallow water it would be possible to bring it ashore at any point as far east as Punshuwe Street. Captain Sergeant said that the bridge proposed by the Harbour Bridge Association was a fixed one, starting at road- level at the end of Beaumont Street, Freeman’s Bay, and rising to u height of 86ft in the centre with a span 300 ft wide and then dropping again to road-level at the northern bridgehead in Shoal Bay. The route suggested was approximately 5,650 ft to the northern bridgehead in Shoal Buy, thence by radiating embankments across Shoal Bay, approximately 3,150 ft to the south end of Sulphur Beach, Northcote, and in a north-easterly direction, approximately 3,300 ft to Bayswater, and from Bays water across the entrance of Ngataringa Bay. approximately 4,200 ft, to Stanley Bay, traversing a total distance of approximately 16,300 ft. The actual bridge route would cross approximately 2,100 ft of deep water with a depth of from five to ten fathoms at low-water spring tide. SERIOUS OBSTRUCTION Considering the requirements of navigation he was of opinion that the proposed bridge could not be entertained. lie said it would cross the main fairway of the harbour in close proximity to the Western Wharf and would create a very serious obstruction and u very real danger to large vessels which require to manoeuvre in that vicinity when leaving Western Wharf and other main wharves on a flood tide during easterly weather. Furthermore the proposed bridge, with a vertical clearance of 86ft and one horizontal span of 300 ft, would prevent or seriously restrict shipping from proceeding to the upper portion of the harbour, and would make it impossible for large vessels to proceed to the westward of the proposed bridge. The future possibilities of the port were enormous, and it might be necessary at some future date to make use of the valuable foreshore of approximately two miles, in length between Northcote and Kauri Point for pert expansion. It must also bo remembered that there was a splendid waterway extending from Kauri Point to llobsonville. It was reasonable to assume that when a bridge was constructed across the harbour great development would take place on the northern shore, which would necessitate the construction of additional berthage accommodation on that side of the harbour and along the foreshore just mentioned.

“Although I believe that the upper harbour will be utilised at some future date for port expansion and wharf construction, and will be used by large cargo steamers, I do not consider that it will be required for large passenger steamers, as tho present commercial harbour will always be used for those vessels. In my opinion the masts of vessels which will use the upper liarhour in the future will not exceed 3 45ft and in fixing the 150 ft vertical clearance 1 have assumed this opinion to be correct.” Captain Sergeant said that since the question of tho bridge has been under discussion a record has been kept of the heights of masts and funnels of steamers entering the point. The highest masts and funnels are those of the Aorangi, which are 170 ft and 106 ft • respectively. VARIOUS SITES “From the point of view of navigation no serious objection could be raised to any of the following routes lor a harbour bridge: “(1) Stokes Point, Northcote, on a line 195 degrees to Ponsonby, a distc^l ce - to land of approximately 4.750 ft, or slightly over three-quarters '>f a mile. This route would cross 2.100fc of deep water with from 5 to 3 2 fathoms at 1.w.5.t., and would be practically at right angles to the run ef the tide. Birkenhead Bluff on a line 179 deg to Watchman Island, a distance «>f 4,400 ft, thence to Point Erin, or Herne Bay shore, a distance of approximately 2,250 ft, making a total distance of approximately 6,650 ft land to land. This route would cross I,Booft of deep water with from five to nine fathoms at 1.w.5.t., and would also be practically at right angles with the run of the tide, and would have this advantage that for the northern bridgebead there would be available the naturally high land at Birkenhead, the termination of tho main highway to the north. The deep water channel is in close proximity to the Birkenhead shore. “*3) Kauri Point to the end of Point Chevalier reef, a distance of approximately 2,300 ft from rock to rock, but with only' 850 ft of deep water to cross with from five to 13 fathoms at l.w.s.t:, thence along the reef toward the western end of Herne Bay, a distance of approximately 7,500 ft, and a total distance of approximately 9,800 ft. This reef dries sft at l.w.s.t. and might offer a natural foundation for a bridge. “Of these routes. No. 3. Kauri Point to Point Chevalier Reef will probably not be entertained owing to the distance from the city and the populated areas of the North Shore boroughs. Of the remainng two routes. No. 1. Stokes Point, Northcote. to Ponsonby, will, in tny opinion, interfere the least with navigation in the harbour.” Captain Sergeant gave reasons, relating to tidal flows and eddies, locality ot* the channel and wind directions, owing to which ho considered that there should be two spans, each with a horizontal clearance of not less than 60oft, which must be regarded as a minimum. Two spans of l,oooft each Would be preferable. The chairman thanked Captain Sergeant for the clear way in which he bad placed the facts before the commission.