Projecting Success

Bradfield (third from right on platform) at Wynyard station, Sydney.

Infrastructure projects are what governments are supposed to do well. A visionary project completed on time and under budget ensures a revered place in history for all involved. By Nick Cater.

The fresh focus on infrastructure by the federal government will be welcomed by almost everybody with the exception, perhaps, of the Greens for whom the threat to life of a single earthworm is reason enough to stop bulldozers in their tracks. 

For those of us who believe the wellbeing of humans should be our top priority, public investment in new dams, pipes, roads, rail and airports offer the promise of economic benefits and amenity into the future.

The caveat is that money should be spent wisely, something that requires a degree of discipline and skill frequently missing from government-funded mega-projects.

The contrasting stories of two tunnels in Sydney illustrate the attention to detail and imagination that separate the good from the bad.

The first is the railway tunnel from Wynyard station to the Harbour Bridge, completed in the early 1930s under the supervision of the great John Bradfield, one of Australia’s greatest engineers. 

For a railway it is a steep incline, which might have created serious problems had Bradfield not intensively researched his subject.

Before work was commenced, Bradfield studied the capability of the latest electric trains to ensure they would have the power and the traction to cope with the incline. They did.

Fast forward almost 70 years to the construction of the M5 East Tunnel by the Carr Labor government, a road engineering exercise that achieve the rare feat of boosting congestion rather than busing it.

The tunnel was at full capacity within months of being opened in 2001, thanks in part to a short-sighted decision to dig two lanes in each direction, rather than three.

But it gets worse. Like the Wynyard tunnel, it has a steep incline, a gradient of 8 per cent. Unlike Bradfield’s design, however, little attention appeared to be paid to how traffic would cope.

The incline travelling west has the effect of slowing heavy vehicles dramatically, banking up traffic behind. It causes frequent accidents, all of which add to travel times which in turn add real costs to economic activity.

The road tunnels under construction today in Sydney have avoided that mistake. Transurban’s 9.5 km NorthConnex tunnel linking the city to the M1 Pacific Motorway will run at points more that 80 metres below the surface yet has a gradient of just 1.5 per cent.

When completed next year it is forecast to take 5000 trucks away from congestion black spots like Pennant Hills Road, with the gradients low enough to keep them moving underground.

Engineering innovation has made executing projects such as these easier and relatively cheaper than they were at the turn of the century. This video shows how Engineering innovation has made executing projects such as these easier and relatively cheaper than they were at the turn of the century.

Cost-benefit analyses for infrastructure projects are inevitably built upon untested assumptions. There is the ever-present risk that Flyvbjerg’s Iron Law of Megaprojects would apply. Project management expert Bent Flyvbjerg’s studies show that planners always underestimate time and cost and overestimate the benefits. 

Yet controlled over-engineering, the construction of a project to a specification above immediate requirements, can pay dividends over time.

For one of the most elegant examples of over-engineering we return to Bradfield and his most famous legacy, the Harbour Bridge.

In 1989 I directed Bridge Builders, a documentary for the BBC on the construction of the Harbour Bridge and an older steel-arched bridge across the River Tyne in Newcastle, both built by the UK company Dorman Long.

The Sydney Harbour Bridge is the longest dual-pinned, steel-arched bridge in the world, capable of carrying many times the weight of traffic than it has ever been called upon to do.

That, however, has given it a working life that stretches far into the future, What is more, it is a magnificent example of the engineering form on display, an inspiration both in form and function.