The two Phillip Island bridges by Marcia Tanswell

Last updated on 6 August 2015

 

THE TWO PHILLIP ISLAND BRIDGES

A Paper written for the Phillip Island & District Historical Society 1983, revised 1992 by Marcia E Tanswell.

 

PRE-BRIDGES

Early settlers brought stock and supplies from, and transported their crops to Melbourne by sailing ship,  a hazardous journey from Western Port to Port Phillip Bay and back.  Individuals could also sail or row to the Mornington Peninsula and be carried by coach to Melbourne.

After Koo-wee-rup swamp was drained, coaches and later motor vehicles, were able to reach Griffith’s Point (now San Remo).  From here, Mr Charles Grayden rowed people across The Narrows to Newhaven.  Stock had to swim across – from 1908 to the 1920’s.

THE PUNTS

In 1929, Phillip Island was reached by a two car punt, plying between San Remo and Newhaven; an unsatisfactory crossing which by 1938 had been replaced by a six car punt.  A large ferry taking 36 cars and 400 passengers also ran between Cowes and Stony Point.

The Cowes ferry made one trip per day, except at peak holiday time, and the punt ran as required during daylight hours only.  These poor facilities cost travellers 10/3d per car and 2/6d per person.  In addition, the approaches to the punt were so bad that vehicles had to be driven at times through fast flowing salt water.  The economic justification for a bridge was obvious and in 1938 it was decided to build a bridge between San Remo and Newhaven.

This ended a long struggle from 1935 headed by Mr Richard Grayden who had talked of a bridge since the early 1920’s.  Pressure from locals through “The Bridge League” and an overwhelming vote at a meeting in Cowes, attended by the Premier Mr A A Dunstan, decided the matter.

In 1936 a branch of the Victorian Country Party was formed on Phillip Island, Mr R A Grayden, President, and Mr Rupert T Harris, Secretary, to bring greater pressure on the Government to build a bridge.  At the first meeting Mr Harris, who subsequently gave unstintingly of his time, limited finances and travelled many times to Melbourne, moved that all in the Party’s power be done to persuade the Government to build a bridge.

In April 1939 the first pile was driven.  Twenty months later, on Friday, November 29th, 1940, the Premier Mr Albert Dunstan cut the ribbon and declared the first bridge open.

THE SUSPENSION BRIDGE

In 1938 funds were limited and the engineering problems of bridging the channel between Phillip Island and the mainland were tremendous due to the depth of water, strong tidal conditions and need for a clearance for fishing vessels to pass under.  It was therefore decided to construct a suspension bridge, to cater for loads up to six tons, which could be built for an outlay of about £50,000 ($100,000).

Work started in November 1938 on a bridge 1,765 feet long and 18 feet wide (approx 538 m x 5.4m) between kerbs with no footway, but with six pedestrian refuges along its length.  The 500 ft (152.4 m) long suspension span crossed the section of deep and fast tidal water which would otherwise have entailed costly foundations.

The main cables used were second-hand from the North Shore Bridge, Sydney, and the second-hand cable hangers from the Tramways supported the wooden decking.

By 30th June 1940, anchors and temporary trestles for construction purposes of the Newhaven approach, piers, suspension span towers and most of the decking on approach spans to Newhaven, plus 75 sheets of plans were completed, for £32,683 ($65,366) for the year.

When erecting the steel towers for the suspension cables, they had to be guyed with cables across the main span and back due to movement of up to two feet (60cm) at the top, until the main cables were finally loaded with the dead weight of the suspension span.

It was not the general rule but some piles with tapering sides penetrated less than those with parallel sides.

Opened by the Premier, Mr Albert Dunstan on Friday, November 29th, 1940, the suspension bridge gave good service, but its load limit caused some difficulty – as passenger buses had to off-load their passengers to walk the 1/3 mile across, while the buses drove across unloaded.  Stock too, could only be taken in limited loads, though evidence showed this was not always observed.

STATISTICS

The bridge was designed by Country Roads Board (CRB) staff under M G Dempster, MCE, Bridge Engineer CRB of Victoria.  Mr C A Masterton, MCEA, MIE, Australia, was responsible for working out detailed design – 75 sheets.  Austral Otis Engineering Company Limited was the contractor with Mr I J O’Donnell, BCEA, MIE, Australia, in charge of field construction until called up for active service in World War II, in 1939.  Mr O’Donnell later became Chairman of Victorian CRB, 1963 – 1971.  (Country Roads’ Board is now Vic Roads)

When built, it was the longest single span of any construction in Victoria and a most picturesque scenic attraction of Phillip Island.

Demolition of this highly picturesque bridge after opening of the new Phillip Island Bridge will be touched on later in this paper.

THE EXISTING BRIDGE

Due to the limited finance for construction of the old bridge, use of so much second hand material, loading of only six tons gross on two axles in each lane, and rapid increase in weight and density of road traffic since the end of the 1939-1945 war, consideration was given to constructing a more modern bridge.

CRB traffic count in March 1960 was 635 vehicles per day, whilst in December 4,730 vehicles per day, and up to 6,263 vehicles per day.  Permission for eight ton loads to cross the bridge was given and even heavier loads were believed to be crossing.

When, in 1959, one of the end hangers supporting the deck from the main cables in the suspension span broke at the lower end and the sea, air and tides had taken their toll from foundations upwards, the decision was made to build a new bridge.

ALTERNATIVE ROUTES

As Cowes was the main centre on the Island and Melbourne (45 miles north – 72 kms) the main source of traffic, three feasible routes were considered:-

            a)         Via Somers.  Most direct route (48 miles – 76.8 kms) involving three mile (4.8 kms)  crossing over the sea which because of potential deep water port area, would  require high level bridge over the main channel.

            b)         Via Stockyard Point and French Island.  This route is 70 miles (112 kms), would give access to French Island, still involves three mile (4.8 kms) crossing over the sea in shallower water requiring provision for fishing vessels only.

            c)         Via San Remo – Newhaven, the present route with length of about 84 miles (134.4 kms)

It is interesting to note that after site investigation, the site chosen was that suggested by Mr Grayden for the first bridge in 1938.

SITE INVESTIGATIONS

These included the following:-

1.         Hydrographic survey.

2.         Underwater inspection of the channel and sea bed.

3.         Seismic traverses.

4.         Core boring at each shore line.          

5.         Penetrometer soundings.

Due to special conditions an additional loading was proposed for design of bridge piers to allow for a boat colliding with a pier.

Many features had to be considered right down to the annoying little bump felt by motorists as they enter and leave a bridge – this has been eliminated.

DESCRIPTION

Finally, it was decided to build the bridge of reinforced concrete and prestressed  concrete 2,100 feet long (630 m) with a central 200 feet (60 m) navigation span flanked by 150 feet (45 m) anchor spans and 100 feet (30 m) approach span on each side.  The bridge is 28 feet (8.4 m ) wide between kerbs with a 5 foot wide (1.5m) footway.  Navigational clearance at high tide is 40 feet (12 m)

Beams in superstructure:-

            80 Pre-tensioned ‘T’ beams each 100 ft (30m) in 16 approach spans.

              5 Pre-tensioned ‘T’ beams each   92 ft (27.6m) in suspended main navigational span.

            10 Post-tensioned segmental beams each 204 ft long (61.2m) spanning anchor spans and cantilever approx. 50 ft (15m) into the main navigational span.

Large quantities of concreting used:-

            Roadworks – Pavement 8 inch (22cm) base course, 6 inch (15cm) fine crushed rock, top course and 1 inch (2.5cm) asphalt surface.

CONTRACTORS

The contract for construction of the bridge was awarded to John Holland & Company Pty Ltd., in April 1966, who elected to work from a temporary steel bridge.

Foundation and superstructure:  spread footing, cylinders or piles used according to ground conditions which generally consisted of basaltic clay.  Special arrangements were made to counter corrosive effect of salt water.  The piers are reinforced concrete portal frames with sloping column legs.

The suspended span, with 92 ft (27.6m) long beams, has a pre-stress of  775,000 pounds (1,705,000 kg)  in each beam.  Handrails of aluminium.   More detail of coffer dams, beams, piling and cylinders may be supplied upon request.

Five sub-contractors and material suppliers were used.

The bridge was officially opened by the Hon. M V Porter MLA, Minister of Public Works, on November 21st, 1969.

Cost:    $3.25 million.

It is interesting to note that its designer, Mr Tom Russell, has been chairman of the Country Roads Board since 1978.

DEMOLITION OF FIRST BRIDGE

A contract was let to demolish the suspension bridge.  Despite local rumours it was not re-assembled in Adelaide or Japan.

Due to the original use of so much second-hand material (mentioned earlier) and the effects of the elements, not a great deal was worth salvaging.  What could be was sold, and it is of interest to note that some of the metal and decking was bought or acquired by local people.

Pieces of metal cable still reappear at the Phillip Island Shire Tip where a lot was buried. The Shire purchased steel girders – devils to work with – which were used for structuring at the Shire Depot.

Islanders found many uses for the old wooden decking, including tables and chairs and a small bridge across a waterway at the Phillip Island Golf Club.

The worst part of the demolition for locals was the continuous blasting out of the old foundations.  Before each detonation, a boat with a man standing in it with a loud hooter, would travel up and down the San Remo beaches warning people to leave the water for fear of broken ear drums and/or death.

Many fish died.  Others were frightened away from the area and fishing conditions did not return to normal for at least two seasons.

Old World Beauty has gone:  replaced by streamlined modern practicality!

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