Narrows Bridge (Perth) - Second Road Bridge: 2001

Second Road Bridge: 2001

Plans for a second Narrows Bridge were mooted during the 1970s, but did not eventuate. By 1998, the original bridge was carrying 155,000 vehicles per day, with an average of 2,700 cars per lane between 7:30 am and 8:30 am, and was thought to be the busiest section of freeway in the country. This quantity of traffic far outstripped the expected capacity of the bridge when it opened in 1959. The solution to the traffic problem most favoured by road planners in 1998 was to widen the existing bridge by building a smaller second traffic bridge just west from it and joining their decks to form a contiguous roadway. This would increase the number of traffic lanes from seven to 10. The widening was expected to cost $50 million.

A plan to widen the Narrows Bridge was announced on 13 April 1998 by the Court Liberal State Government. The $70 million plan would involve the addition of four extra traffic lanes, and was part of a $230 million package upgrading and extending the southern end of the Kwinana Freeway. Alannah McTiernan, then the Opposition Transport spokesperson, attacked the plan, saying that the government should instead build a railway to Rockingham.

Instead of widening the existing structure, Transport Minister Eric Charlton on 15 July 1998 approved the construction of a separate second road bridge alongside the original Narrows Bridge; this solution would cost $15 million less, due to new building techniques, and would be less disruptive to traffic on the existing bridge. The construction of a separate bridge was also deemed necessary because the foundations of any new structure might settle in the soft river bed at a different rate to the existing bridge. Under the plan, there would be six lanes on each bridge, including a bus lane on each. The new bridge would run parallel to the original bridge and be separated from it by a gap of 6 metres (20 ft), and was designed to look largely the same as the original.

Main Roads called for tenders for the bridge widening in July 1998, and on 7 March 1999 it was announced that the building contract had been awarded to Leighton Contractors. The negotiated contract price was reduced to $49 million owing to the construction method proposed by Leighton. The designers were Connell Wagner.

The bridge was constructed by the incremental launching technique, with 28-metre (92 ft) segments pre-cast on both shores and pushed out into place as the construction progressed. The bridge was divided into two strips lengthways, with the eastern half launched separately from the western half, and the two decks were later joined at the bridge's centre line. The first of twelve segments was launched in February 2000.

As it was being launched, the bridge rested on temporary piles; only after the structure was fully launched were these piles removed and the bridge allowed to rest on its permanent supports. The construction required the driving of around 250 steel piles; the first was driven on 10 August 1999.

Construction of the second bridge was interrupted several times by strikes, as well as by an algal bloom in the Swan River. The bridge was finally opened to traffic on 26 February 2001, and officially opened by new Transport Minister Alannah McTiernan (a strident critic of the project) on 30 May 2001. The bridge had originally been planned to be opened in August 2000, and was expected to carry 80,000 cars per day. The new traffic bridge carried six lanes of traffic, including one bus lane, and the original bridge was modified at this time to carry six traffic lanes, as designed.