Myth: A continuous freeway network will eliminate bottlenecks

Fact: Linking freeways only shifts bottlenecks from one place to another, as people still have to reach their final destinations.

Everyone in Melbourne knows that there are freeways that appear to ‘dead-end’, as the Eastern Freeway does at Hoddle Street. Isn’t it reasonable for the government to connect the dead-ends, so traffic can flow seamlessly from one freeway to another?

A bit of history is helpful. Most freeway proposals for Melbourne date back to the 1969 Melbourne Transportation Plan, which proposed a Los Angeles-style grid of freeways criss-crossing the entire city. The present Eastern Freeway appears in this plan as the F19, originally intended to continue through the centre of Fitzroy and Carlton and join another inner-city freeway in North Melbourne.

These inner-city links in the 1969 plan were cancelled by Premier Hamer in 1973 because they would have destroyed thousands of homes, historic buildings and parks. This decision was reaffirmed by the Federal Government in 1974. The Eastern Freeway was not opened until December 1977, so the ‘dead-end’ was created by road planners with full knowledge of the problems it would produce.

Now that the Eastern Freeway extension has heightened pressure on this deliberately-created dead end, road lobbyists (most recently Sir Rod Eddington in the East-West Link Needs Assessment) have called for the reinstatement of the inner-city freeways.

[The transport industry] is pushing for [the Eastern-Tullamarine link] to avoid a nightmare gridlock scenario once the Mitcham-Frankston Freeway opens in 2008….The government official in charge of the Mitcham-Frankston Freeway, Ken Mathers, has urged road users to lobby for a solution to the notorious snarl….He said road users should be telling politicians that something needs to be done to the city end of the Eastern Freeway.

—Herald Sun, 23 August 2004

The daily queues on the Eastern Freeway are a constant reminder that this is the last of the major freeways terminating on the fringe of the inner city, with the freeway coming to an abrupt halt at Hoddle Street…. Substantial new investment in the city’s road network is needed to meet the growth in cross-city travel demand.

—East West Link Needs Assessment (2008), Chapter 5

So, freeways do not solve anyone’s problems; they just create demand for more freeways.

It is also misleading to suggest that most freeway traffic is headed for another freeway. People don’t drive around just to explore the freeway system: they have a final destination which usually is off the freeway altogether. In the case of the Eastern Freeway, the Government’s own Northern Central City Corridor Study showed that only 15% of the traffic (including the trucks) is heading for the Tullamarine Freeway or due west; the vast majority is headed for the city centre. Extending the Eastern Freeway inward would just shift the bottleneck at Hoddle Street to other roads like Nicholson Street or Lygon Street. The desire to drive into the CBD will not disappear just because two freeways have been joined up.

Many bottlenecks perform a metering function, by reducing the flow at one point to a level that can be sustained in downstream sections of roadway. Removal of the bottleneck in one location may simply result in transferring the bottleneck to another point downstream. In many cases the newly formed downstream bottleneck may result in worse traffic conditions than maintaining the original bottleneck. Thus, bottlenecks may often play a useful and important function in regulating flows and controlling the level of congestion that occurs on a road network.

—David Metz, The Limits to Travel, 2008

Freeways as backup for other freeways?

Closely related to the ‘bottleneck’ furphy is the idea that new freeways provide ‘redundancy’ or ‘backup’ for existing freeways – an idea recently popularised by the Eddington East-West freeway proposal. This argued for a new freeway tunnel between the western suburbs and Citylink primarily on the grounds it would provide an ‘alternative’ to the West Gate Bridge if the bridge were unavailable for any reason.

The only way this could possibly work, though, is if the road were built and then kept empty pending an emergency. If traffic is allowed to actually use the ‘alternative’ road, then it is no more an alternative than the Harbour Tunnel in Sydney is an alternative to the Sydney Harbour Bridge. If the Harbour Bridge ever had to be closed in peak hour, bridge traffic would be unable to use the Harbour Tunnel, as the tunnel would be full of its own peak hour traffic already!

In Melbourne, there are already three major arterial roads crossing the Maribyrnong River south of Flemington Racecourse, and providing alternative routes to the West Gate Bridge. Naturally, none of these is capable of carrying the amount of traffic that uses the West Gate in peak hour, but neither is any road – however large – once it is carrying a peak hour ‘traffic load’ of its own. As long as they are used for their intended purpose, the value of new freeways as ‘backup routes’ is entirely illusory.

Experience also shows that even when there is spare capacity on a toll road (as Eddington’s tunnel would doubtless be), motorists are reluctant to use it as an alternative to a parallel route that is blocked. For example, Sydney’s new Lane Cove Tunnel runs parallel to Epping Road, and much of the traffic approaching the tunnel from the M2 motorway actually exits onto Epping Road to avoid the toll. When Epping Road was closed to eastbound traffic due to a fatal crash on 9 September 2008, motorists didn’t switch to using the tunnel: instead they dispersed onto every other arterial road in the area, blocking traffic in all directions for about 5km.

Conclusion

Current freeway plans are not just about making a few links to fix bottlenecks. They actually propose to more than double the size of the existing freeway network. This will increase traffic problems on other roads, not reduce them. The road planners are proposing ‘more of the same medicine’ to address problems that they themselves created. It’s time we stopped taking the medicine and switched doctors!

As part of the switch, it is possible to turn ‘dead ends’ from a problem to an advantage. Since most traffic on Melbourne’s radial freeways is heading to the central city, it should be possible to apply a ‘demand management’ scheme similar to that used in Copenhagen. Traffic lights at the city ends of Melbourne’s radial freeways can be used to limit the amount of traffic entering the city to a level that does not overcrowd roads in the centre. A strategy of this kind will work best when accompanied by radically improved public transport, as the PTUA proposes elsewhere.