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Common Urban Myths About Transport

Myth: Freeways relieve traffic congestion
Fact: They may provide some short-term relief, but within a short time the extra road capacity generates more traffic than there was before. In the long term freeways just allow congestion to grow further: they don't reduce it.

It was hailed as a solution to some of Melbourne's worst traffic problems. Now, four years after it opened, the CityLink tollway is the focus of a new traffic nightmare - worsening peak-hour congestion on the roads that feed into it.
---The Age, 11 November 2004

The Western Ring Road has been an outstanding success since it was built in the 1990s. However, the ring road is now experiencing high levels of congestion, particularly in peak periods, and it is time for its capacity to be significantly enhanced.
---Roads Minister Tim Pallas, Laverton Star, 10 July 2007

Road planners often promise that freeway building will relieve traffic congestion, especially on the arterial roads that freeways bypass. But the promised relief, if it arrives at all, is usually only temporary.

Official acknowledgement that freeways do not relieve traffic congestion is found in numerous places. For example, in April 2005 VicRoads told a planning panel examining new road construction in central Geelong that the $400 million Geelong Bypass will not, as popularly supposed, relieve traffic congestion on major roads like Latrobe Terrace. Supporting the proposed removal of a heritage overlay to allow a left turn slip lane to be built, VicRoads submitted that

there is likely to be a reduction in traffic volumes of up to 17% in Latrobe Terrace.... immediately on completion of the Geelong Bypass. However the natural growth of traffic (approx 2% per year), as well as a redistribution of traffic from other north/south routes, is expected to result in traffic volumes.... returning to their pre-Bypass volumes in a relatively short period of time.

Similarly, a 2004 report by traffic consultants Parsons Brinkerhoff for the City of Whitehorse confirmed that building the Mitcham-Frankston Freeway (MFF) will do nothing to relieve traffic congestion at the intersection of Springvale Road and Whitehorse Road.

[T]he analysis demonstrates that in future years the existing arrangement and [proposed] intersection treatments result in the Springvale / Whitehorse intersection operating either at or over capacity for traffic scenarios which assume the MFF to be operating (tolled or otherwise). This is an important conclusion as it indicates that the Springvale / Whitehorse intersection will operate overcapacity in future years, even in a traffic scenario which assumes MFF is to be built i.e. solely relying on the traffic redistribution effects of the MFF is unlikely to provide a long term solution to the problems of the Springvale / Whitehorse intersection.
---Springvale Road Traffic Improvements Feasibility Project Stage 2: Final Option Review, August 2004, p.25

EASTLINK will not ease traffic congestion in Whitehorse, with the long-term outlook for roads hopeless, a Whitehorse councillor says. Cr Chris Aubrey said the heavy congestion on roads such as Springvale Road in Nunawading would not be eased in the long term by EastLink. In the first year of the freeway [EastLink], traffic will be reduced by 20 per cent but every year there is a 7 per cent increase in traffic. So in two to three years it will cancel out.
---Traffic Trouble, Whitehorse Weekly, 8 March 2006

But the best known official debunking of this myth is the report of Britain's Standing Advisory Committee on Trunk Road Assessment (SACTRA) in 1994. This states:

Increases in traffic on improved roads are, in general, not offset by equivalent reductions in traffic on unimproved alternative routes.

The first reason freeways fail to relieve congestion is that freeway traffic still has to go somewhere before and after it uses the freeway. Prior to the construction of CityLink, VicRoads published figures showing that many roads allegedly 'relieved' by CityLink would actually be carrying more traffic after City Link opened than before. Some of this would be through toll avoidance: thus VicRoads predicted that traffic in Mount Alexander Road would more than double, a prediction that has since come to pass. But they also predicted an 80 per cent increase in traffic in Gatehouse Street, a 65 per cent increase in Peel Street, and even an increase on Punt Road at the freeway junction. These increases had nothing to do with people avoiding tolls, but rather the effect of drivers changing routes once CityLink was in place.

The second reason is that new roads create new traffic. Thus, even the Vicroads figures above have actually proved to be too low. Indeed, VicRoads and other road lobby consultants have consistently underestimated the traffic consequences of new roads in their traffic studies, such as for the Mulgrave-South Eastern Freeway link in the 1980s and the Eastern Freeway extension in the 1990s. This is because their computer models assume that improved roads don't generate any additional traffic.

Even as recently as 2006, the Bracks Government touted a consultants' report claiming the EastLink tollway would bring $15 billion of economic benefits to Victoria. Yet the report's authors admit that the figure was obtained by assuming not one extra car trip would be made as a result of the road being built.

The analysis assumes that the projected demand is from vehicles that would have otherwise used the existing arterial roads, such as Springvale Road and Stud Road. In other words, it assumes that all vehicles travelling on EastLink will incur time savings because they would have otherwise driven on arterial roads. If some of the vehicle journeys are actually 'induced' by EastLink, meaning that they would not have occurred if EastLink did not exist, then the time savings counted in our analysis is an overestimate because 'induced' vehicle journeys do not result in time savings. It is not possible to obtain an estimate of the number of vehicle journeys induced by EastLink; however, we believe the number would be small.
---Allen Consulting Group, Economic Effects of Eastlink, 2006, page 11

The evidence, both statistical and anecdotal, shows otherwise. Though new roads do temporarily reduce traffic flows on parallel routes, this relief is almost completely wiped out after a few years. Take for example the link between the Mulgrave and South Eastern Freeways built in 1988:

Traffic Flows on Roads Parallel to Monash Freeway
(vehicles per day)
YearWaverley RoadHigh Street Road
198231,000
198328,000
198632,500
198832,00022,000
(Mulgrave - South Eastern link opens)
198913,90017,500
199628,00023,000

Source: ARRB Transport Research, Report No. 299

Three days after [the freeway] opened, I went to check out Waverley Road in the morning peak....it was dead quiet. Not a car hardly. Freeways are great, I concluded. The freeway has removed all this traffic.
Step forward roughly 13 years and we are living elsewhere and I suggested to R that a good way to work was Waverley Road. He said no. It is too busy. Step forward a few months and I had an occasion to see Waverley Road in the morning peak and I was astonished that it was just a long line of stop and start cars.
What changed? The number of cars grew because the ease of travel grew.
---Andrew of the High Riser blog

Has no one asked why the Monash tollway is still 40 minutes outbound in peak hour, just like in the old days of the South-Eastern 'car park'?
---David Bowker, letter to The Age, 14 June 2005

When they put in the Hallam bypass a few years ago traffic conditions improved noticably for a little while but the volume of traffic went up noticably shortly after and all benefits were obliterated.
---Post to melb.general newsgroup, September 2006

While all that new traffic was flocking on to the Monash Freeway and the roads parallel to it, the road lobby was building CityLink, whose marketing material proclaimed it to be a lasting solution to Melbourne's traffic problems such as those caused by the 'dead-ending' of the Monash Freeway at the city end. Cold reality has proved otherwise: barely five years after CityLink opened in late 2000, the Monash Freeway was called the worst freeway for traffic delays by the outgoing CEO of VicRoads. In 2006 the road lobby succeeded in getting more lanes added to this freeway in order to encourage even more traffic, but this hasn't stopped the RACV calling the barely-five-year-old CityLink slow and congested and a source of frustrating delays, which they say can only be fixed by building another freeway - this time through the Yarra Valley.

Meanwhile, the parallel King Street route through the CBD is still classified as a major freight route by the road engineers at Melbourne City Council, and this is given as a reason why more priority can't be given to trams on the cross streets. Needless to say, things would be very different if CityLink had really taken all the trucks off King Street, the way it was supposed to do. But while car and truck trips have shifted from King Street to CityLink, just as many entirely new car and truck trips have appeared to take their place.

The story is the same in Sydney. In 1992 the Sydney Harbour Tunnel opened amid promises that it would fix traffic congestion on the Harbour Bridge forever. The truth is quite different, as the traffic counts show:

Traffic Flows on Sydney Harbour Bridge
(vehicles per day)
YearAverage Flow
1970129,000
1980159,000
1987180,366
1989182,024
1991181,878
(Harbour tunnel opens)
1992138,400
1995150,889
2000161,000
2005180,000 (est.)

After remaining steady over the five-year period from 1987 to 1991, traffic levels both on the bridge and in the tunnel increased throughout the 1990s as Sydney swapped a congested bridge for a congested bridge-and-tunnel. The final cost of the tunnel was $738 million in 1992 dollars; a high price to pay for just a few years of reduced congestion. Traffic levels in the tunnel have now reached 80,000 per day, meaning that its effect has been not to reduce congestion but instead to increase the number of cars crossing the harbour by nearly 30 per cent - despite no similar increase in the size of the central Sydney workforce.

In the 1950s, American transport planners used to claim that roads respond to traffic, but don't cause it. This is nonsense, of course. Road engineers used to be the only business people who thought that if they improved their produce, they wouldn't get more customers! VicRoads planners are still stuck in the 1950s, denying that road building will produce additional traffic.

Gordon Price: I simply ask people: show me the example where this has worked. All I want is for a working example of a city that has built its way out of congestion simply by building more roads, and then is that the place you want to be? I don't get an answer to A or B.
Peter Mares: You mean, there's never been a city that's managed to fix congestion by building more freeways or more roads?
Gordon Price: You might argue that Houston, Texas has. They throw about $1-billion a year into it, they do keep the traffic moving. Do people want to be like Houston? Can you be like Houston? Are you prepared to spend that amount of money and is that really the kind of city that you want in the end? And they have to run as fast as they can just to keep where they are. And they're looking at transit too!
---Gordon Price (Transport Planner, Vancouver, Canada), ABC radio interview, February 2007

Outside the cut-and-thrust of political lobbying, the new traffic created by new roads is tacitly acknowledged in official circles. The Australian Institution of Engineers, the professional body representing road builders, says in its policy material:

New urban roads always attract traffic....the two main sources are induced traffic (trips that would not otherwise have been made had the road not been built) and diverted traffic (trips that would otherwise have followed some alternative route).
---Australian Institution of Engineers, 1990

And very occasionally, the new traffic 'induced' by new or bigger roads will be acknowledged by the government, sometimes even in the same breath as they call for even more new or bigger roads in order to reduce traffic congestion. Thus, the following statements are juxtaposed on the same page of a State Government brochure, apparently without irony:

Some 48km of the Princes Highway between Melbourne and Geelong has been widened and interchanges have been upgraded... There has been about a 16 per cent increase in the volume of traffic travelling along the upgraded section of Geelong Road.
The Geelong Bypass will provide a 22km freeway-standard road from the Princes Freeway in Corio to the Princes Highway in Waurn Ponds. The bypass will reduce traffic congestion and delays within Geelong's road network....
---Building One Victoria, Victorian Government, 2005, page 20.

Meanwhile, the Eastlink tollway is likely to increase rather than reduce traffic congestion in the City of Manningham, according to the road planners:

[N]umber crunchers predict Manningham Rd will be bombarded with up to 20 per cent more traffic when EastLink opens, which could be in June. The sharp rise was forecast by the Southern and Eastern Integrated Transport Authority (SEITA) - the State Government body overseeing EastLink's delivery.
The authority's report....also said EastLink's opening would reduce amenity for residents living on Manningham Rd. Koonung Ward councillor Warren Welsh said Manningham Rd was destined to become a traffic sewer if commuters used Manningham as their route to EastLink.
---Eastlink's traffic sewer, Manningham Leader, 15 January 2008

Be prepared for the same road planners to 'solve' this problem with another freeway - just as Eastlink was supposed to 'solve' congestion problems in the eastern suburbs. Proponents of the westward extension of the Eastern Freeway have likewise tried to have their cake and eat it too, citing as a benefit

Reduced road congestion at the city-end of the Eastern Freeway and the inner north generally, which will be exacerbated in 2008 on completion of the East-link project. The [east-west freeway] would enable easier movement by local traffic, tram, bike and foot and improved amenity between the CBD and the inner northern suburbs.
---VECCI Infrastructure Task Force, November 2005

In other words: yes, building Eastlink will increase congestion, but don't worry, this new freeway will reduce it again!

One can also find figures in Vicroads' own annual report demonstrating that building freeways hasn't reduced the level of congestion. In fact, the overall level of congestion (as measured by the average delay to traffic) has remained steady over at least the last decade, with reductions in congestion in some locations evenly balanced by increases in congestion elsewhere. What is even more clear is that freeway-building has increased the amount of car travel by 13 per cent over 10 years, faster than the increase in Victoria's population (even when offset by a slight decrease in 2006 due to higher petrol prices).

Traffic Levels and Congestion
(At urban monitored locations, all times)
Financial
Year
Vehicle
kilometres
Traffic
delay (min/km)
1997-9878,3180.53
1998-9980,7850.50
1999-0082,8030.50
2000-0185,0300.51
2001-0286,4120.55
2002-0386,4600.53
2003-0488,3010.52
2004-0588,6880.57
2005-0688,0410.53

Source: VicRoads, Annual Report 2006, page 57.

The final verdict - that freeways in the long term increase traffic congestion, rather than reducing it - came in 1994 with the release of the SACTRA report mentioned above. The British Department of Transport's own expert team concluded that new roads can and do generate traffic.

Travellers must, as a matter of logic, be assumed to respond to reductions in travel time brought about by road improvements by travelling more or further.
---Standing Advisory Committee on Trunk Road Assessment, UK, 1994

Any transport policy must balance the additional economic activity generated by new roads against the self-defeating gridlock that results. [The SACTRA] report, for the first time, takes into account those drivers who switch from one route to another because of a new road, those who change their destination to take advantage of increased accessibility, those who previously used public transport, those whose journeys were caused by a change in land use and those who previously did not travel.
---The Times (Editorial), London, 20th December 1994

The latest research confirms that this effect works the other way as well: closing roads, or reducing road capacity through traffic calming, can actually cause traffic to disappear!

Who'd have guessed you could shut down a third of [Seattle's] most congested freeway and not paralyze the region in epic traffic jams? Oliver Downs, that's who.... A few days before the state began what it was calling the most disruptive road project in local history, Downs put out a contrary view. He forecast no extreme clogs anywhere - not on I-5, nor on alternate routes such as Highway 99 or 599. So far he's been right about that. Then he crazily suggested that one of our chronically jammed roads, the I-405 S-curves in Renton, would actually be better off than normal. Which it has been.
Downs wasn't dead on. Even his optimistic view was too pessimistic. A stunning 50,000 fewer cars are using northbound I-5 some days. It's slow going in the work zone. But in many places, driving has been smoother than before....
In 1998, British researchers studied what happened to traffic in more than 100 highway and bridge shutdowns in Europe and the U.S. They found that on average 25 percent of all car trips simply evaporated.... Drivers are not stupid, Downs says. They change schedules. They don't take some trips, or they delay them. The net effect of all these little decisions can be dramatic.
---Math whiz had I-5's number, Seattle Times, 22 August 2007

The car works best as a form of travel when few people use it: increasing traffic leads to congestion, making driving less attractive. By contrast, public transport service improves as patronage increases, as frequent services and express runs become more viable. Where public transport and roads are in competition, as in Melbourne, expanding road capacity is a two-way loser. It attracts additional traffic, making road conditions worse, and reduces public transport patronage, making public transport less attractive as well!

Conversely, improving public transport can make life easier for both public transport and road users. Vancouver in Canada has built no freeways for decades, and has invested in public transport instead. In the last decade, average travel times to work have reduced as a result.

This paradox is widely recognised by transport planners overseas, and even has an official name: the Downs-Thompson Paradox. One doesn't have to look hard to find examples of this principle in action.

Case Study No.1:

The extension of the Eastern Freeway to Springvale Road, built in the mid-1990s, parallels and competes with the Lilydale/Belgrave rail line. Currently, the rail line is Melbourne's busiest, carrying around 15,000 passengers in the morning peak hour, just under half its capacity. Although much wider than the rail line, the Eastern Freeway before it was extended carried only about half this volume (8,000 passengers) but even they strained the road's capacity, with traffic banked up at the City end of the freeway for three or four kilometres. Now that the freeway has been extended, the traffic jams have grown to twice as long, and commuters who drive into the city from Templestowe regularly complain about the longer delays due to increased traffic!

(The further extension of this freeway to Frankston is predicted to dump an extra 28,000 cars a day at the City end - many of which would be escapees from neglected public transport services.)

Case Study No.2:

Within weeks of the South Eastern Arterial link opening in 1988, 20% of peak passengers on the Glen Waverley train line shifted to the freeway. Services on the rail line were reduced as a result: in 1987 there were seven peak period expresses on the Glen Waverley line; ten years later there were only two. This has pushed still more passengers onto the freeway, setting up a vicious spiral. Since there are many more rail passengers than freeway users, improvements to the freeway will be cancelled out even if a minority of rail passengers shift their mode of travel. The overall result is that, after the expenditure of hundreds of millions of dollars and the destruction of areas of great scenic beauty, we have worse conditions for both road users and public transport passengers!

Case Study No.3:

With the Environment Effects Statement for the Scoresby Freeway in 1997, we finally got official confirmation in Melbourne that public transport can be a more effective treatment for congestion than new freeways. The government's consultants wrote:

each percentage point increase in PT mode share is estimated to reduce road user costs by about $165 million in 2011....[and there would be] estimated savings in road user costs in 2011 of about $190 million if the Scoresby Freeway is built and public transport mode share is kept unchanged.
---Scoresby Transport Corridor EES Working Papers No.2: Addendum, p.24

In other words, the same savings in road user costs would result from increasing public transport mode share by just 1.15 per cent, as from building the freeway. (In the latter case the savings would of course be only short-term, as traffic levels would soon build up until there is just as much congestion as before.) As soon as it was realised that it might damage the case for the Scoresby Freeway, this finding was buried in an obscure supplement to the EES, and no more detailed investigation of any public transport alternative to the freeway ever took place.

Case Study No.4:

In 2005 the road lobby began agitating for a new freeway parallel to the West Gate Bridge, pointing out that between 1994 and 2004 peak-hour travel time over the bridge had more than doubled, from 11 to 25 minutes. But it turns out that this 240% increase in travel time has resulted from only an 18% increase in traffic volume - from 17,600 cars to 21,800 between 6am and 9am. Public transport in the western and northern suburbs is truly woeful, with trains running only every 20 minutes in peak hour and buses even less often; meanwhile construction of the $630 million Western Ring Road has fed induced traffic onto the bridge. If public transport were improved tomorrow so as to attract one in six journeys away from car travel, traffic on the West Gate Bridge would revert to its relatively free-flowing conditions of 1994. On the other hand, building a second West Gate Bridge is likely to only give us two congested bridges in place of one.

Conclusion

In the heyday of freeway building in the 1950s, the well-known architect and urbanist Lewis Mumford warned that trying to cure traffic congestion with more road capacity was like trying to cure obesity by loosening your belt. The result of too much belt-loosening can be seen throughout the USA, where 'suburban gridlock' is endemic. We are not yet at such an advanced stage of urban decay; we can avoid it entirely if we want to.

Congestion, it turns out, is an inevitable consequence when the private sector produces an unlimited number of vehicles and expects the public sector to spend limited resources to build an unlimited amount of space for them to run on.
---Gordon Price, Transport Planner and former City Councillor, Vancouver


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© 2007 Public Transport Users Association Inc. (PTUA), Victoria, Australia. ABN 83 801 487 611.
General copying and distribution on a non-commercial basis is permitted subject to proper acknowlegement.
Authorised by Tony Morton, 247 Flinders Lane, Melbourne, for the PTUA

Last modified: 29 January 2008

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