If you are a transport planner, it is de rigeur to complain about congestion and the damage it inflicts on the economy and the environment. In the UK these days the Eddington Transport Study is often the source of the statistical 'evidence'. Eddington tells us that "eliminating existing congestion on the road network (relative to free flow conditions) would be worth some £7-8 billion of GDP per annum".
The problem with focussing on congestion is that it leads to demands for government action rather than for moves on the part of the transport sector itself.
Unlike many of the reports that use his numbers for the cost of congestion, Eddington does talk of reliability. However, his footnote on the numbers on congestion – at least, the footnote that makes sense rather than the one referred to in what looks like a proofreading error – says that the figures "exclude potential reliability and agglomeration benefits".
This may change if planners pay attention to a new report from the International Transport Forum (ITF), Improving Reliability On Surface Transport Networks, which suggests that reliability should be given the same sort of policy prominence as that generally given to congestion.
The ITF explains that reliable transport networks and services are required "because of more complex and inter-related supply chains and increasingly complex scheduled activities".
It is surprising that reliability has taken so long to enter into the picture and that "few countries explicitly incorporate reliability into transport policy making". The ITF's report claims that "network and service reliability is not systematically incorporated in the transport planning process and thus is not reflected adequately in decision making". The bad news continues: "Reliability is rarely factored into cost-benefit analysis, the core planning tool for surface transport networks."
The ITF dismisses some of the excuses offered for ignoring reliability. No longer, it seems, can we rely on the argument that you cannot find a way to allow for, or even define, 'reliability': the report talks of "significant progress in identifying methodology for incorporating improvements in reliability into project and policy evaluation, while exploring the pitfalls that need to be avoided".
On defining reliability, the ITF opts for "the ability of the transport system to provide the expected level of service quality, upon which users have organised their activities," while admitting that "expected" is itself open to interpretation.
The report also talks of the needs for cost-benefit analysis of reliability and describes examples of the pilot use of ways to measure and value it, including trials in the Netherlands, Sweden and the UK.
In the final analysis, reliability could be more important than congestion, which is usually more predictable. As the ITF puts it "a congested network does not have to be unreliable".
You can safely say that the M25 around London will be clogged every weekday during the morning and evening rush hours. It is another question as to when the traffic will grind to a halt after an "incident". Similarly, commuters can plan for congested trains but unreliable railways are a nightmare.
There are, of course, limits to what can be achieved. There isn't much that airlines can do when a volcano decides to blow its top at irregular intervals. In any case, the airline heads all know that this is the government's fault. But that is no excuse for ignoring reliability in their own backyards.
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