This is a free translation of excerpts from the inaugural session chair Transport Policy, University College London (UCL), Professor Phil Goodwin .
October 23, 1997
October 23, 1997
My first approach to the formal analysis of transport was the paper of Smeed and Wardrop 1964, written before both came to UCL, surely one of the great classics among transport studies: "An Exploratory Comparison of the Relative Advantage of Cars and Buses in Urban Areas. " His argument was instant attraction (for intellectuals, not always for the politicians) of the counter-intuitive: If everyone were to travel in the slower mode of transport, the bus would travel faster than if everyone chooses the fastest way, the car.
Image: Costanera Avenue roundabout to reach Perez Zujovic, Vitacura, Santiago. (Source: La Tercera)
The reason this is true is a fundamental relationship in our area, the flow-speed curve. This shows that the more traffic there is on a road, the slower is the circulation, an effect that is more and more severe as the flow approaches the maximum network capacity, until finally the overload is so extreme that vehicles can not be moved. We can define congestion as the impedance vehicles impose on others because of this relationship. This helps us understand that the reason behind the congestion is not the work on the road or taxi or an accident: it is trying to operate with traffic flows too close to the network capacity, a situation in which any such incidents have a disproportionate effect.
Armed with this law, Smeed and Wardrop estimated that the number of cars required to move a given number of people is much greater than the number of buses, then a transfer of people from the car to bus would make traffic move more quickly in certain circumstances be sufficient to overcome the extra time waiting for the bus, walk to the destination, etc..
But there is a downside. For us it is almost always faster to travel by car, so we have little incentive to do otherwise. It's one of those cases where individuals pursuing their own good (Adam Smith ) not lead to greater happiness for the greatest number ( Jeremy Bentham). The benefit will only be achieved through intervention is in the allocation of road space, bus-only tracks, for example, or by charging.
Smeed Another important contribution was his participation in the committee road pricing, which in 1964 gave some kind of official approval to the proposal of Alan Walters on economic welfare can be increased if the-road use perceived as a good "free", was reflected in charges.
The reason why road pricing provides a benefit is congestion. Every driver, when using roads or busy streets, imposing delays on all others, and these delays are not considered by the cost driver in their decisions. Thus, some trips are made by a route that the benefit received by the driver is less than the cost (extra time) it causes the rest, so the total time consumption is higher than it should be. But so far the history of road pricing has been marked by study, flirtations, lack of support and interruptions. The reason for this, in my opinion is that nobody has taken seriously the implications of a few lines of calculation in the Smeed Report, which is somewhat obscure show that although certainly road pricing reduces congestion, most of benefits is this relief of congestion, but in the collection that is obtained, which occurs once the benefit is used.
latest analysis shows that if road pricing were applied in a way that also have environmental benefits and provided enhanced economic benefits to commercial vehicles and buses, then amplify total benefits. But the essential point is the same: to a large extent the benefits are realized through the use of money raised. This is the reason why any discussion on road pricing without special attention to the use of proceeds is inherently unlikely to generate a consensus for their support. This is an axiom of contemporary transport policy. Then
Now we have these two important propositions: congestion could be less if people use slower modes, and if you pay for something that they feel as free today (*). As policy statements, lack the appeal to transform them into manifestos. The proclaimed "slow and expensive" does not inspire. But let me suggest another axiom: if there is a policy that genuinely enhances efficiency, then there should be some form of implement to generate support: no benefit to gain, those earning more than the losers.
So why this sounds so unattractive? Where is the flaw in the argument? Where was the defect 30 years ago?
One problem was that the tools we had to understand how individuals made their choices were to go wrong and biased, and another was that the economic orthodoxy wrongly classified the collection of road pricing as a "tax." But the real barrier to implementation was that the spirit of that time was in a completely different direction. Had a more easy, comfortable, modern and entertaining way to solve congestion. Could simply "build our way." If the traffic reaches levels very close to capacity, the capacity increases. Since the late 50's onwards, the traditional transportation planning was what Susan Owens called predict-and-Provide (predict and provide). The axiom was: first predict how much traffic is going to be, then build enough road space to satisfy. This rule resulted in a rapid and massive expansion of roads and highways, now we can not imagine modern life without them. Also resulted in what now appears to be a serious error: The destruction of the heart of some of our cities to make room for new urban highways. Here, our imagination about life without them is easier, indeed in many central places capacity vial is shrinking or closing, in order to return the space to more productive use, although many historic structures are gone forever.
For better or worse, the axiom predict-and-Provide had its highest point, by one of the ironies of history in their final hour, the road construction program in 1989 based on predicted traffic called Roads to Prosperity (Pathways to Prosperity). This was the last time the government proposed a road program that tries to meet demand. It was launched with great fanfare, even though even before the proclamation was already known that such a program could not keep pace with traffic growth.
In fact, the unquestioned study showed that even a fancy program, 50% larger than Roads to Prosperity would not be able to keep pace with traffic growth.
Now, suppose that road capacity is expanded at a slower rate than the increase in traffic What next?
The result is due to arithmetic, not politics. The number of vehicles per kilometer of road could only increase, and therefore would expect the congestion to get worse (either in intensity, duration, geographical area or a combination thereof). Supply road space will not increase, because it can "to meet demand. In practice, predict-and-Provide inevitably means predict-and-underprovide (predict and subprovee). One strategy is to build roads whose base (in cities) will not improve travel conditions. We call this new realism.
mid 90's, the same idea began to spread intercity roads as well, especially after the advisory committee that will report SACTRA road construction when there is congestion, often resulting in an increase in the total volume of traffic, then a short period of relief from congestion, relegating to history untenable claim that the volume of traffic is not affected by the conditions of travel. This opened the door to recognize that the amount of traffic is, in part, a result of policies, and therefore is subject to some degree at our discretion.
So we have two propositions: we can not adjust the supply of road capacity to projected demand, and demand is not inoxerable, exogenously given, is subject to influence.
(continued)
------- (*) Finally, congestion charging was introduced in central London in 2003.
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