Institute for Transport Studies (ITS)

Can we Learn Anything from the Forth Road Bridge Failure?

By Professor Greg Marsden

The closure of the Forth Road Bridge on Thursday left 100,000 people and major businesses such as Amazon facing large diversions and substantial delays in the immediate aftermath of the closure. At times like this a cottage industry in back of the envelope calculations rushes to estimate the disastrous costs to the economy of the closure and there is a clamour for something to be done.

Stepping back from the Forth Road Bridge for a second it is not long since there was collective hand wringing over the Dawlish rail line collapse, the flooding of the Somerset levels or the closure of Heathrow through snow and ice. Infrastructure failures and closures are a fact of life. Whilst the agencies that maintain our infrastructure seek to protect us against the most frequent and most important problems we can be certain about two things.

First, it rarely stacks up economically, financially or politically to protect infrastructure against low probability high risk events.

Second, even were we to pursue such a policy we would inevitably be blind to some risks be they climatic uncertainty or terrorism (the Brussels Metro was closed for four days after the recent Paris terrorist attacks and significant failures of some kind would still occur.

There is however a significant body of research that tells us that, if well managed, major changes to the availability or quality of service of infrastructure are not catastrophic. Our travel patterns develop because we plan our lives around a set of expectations of the likely journey times and journey quality by different modes. We base our home, work, schooling and leisure choices around an increasingly complex and time constrained pattern of journeys. Provided we can relax some of the constraints around which we structure our everyday life then adaption becomes possible. The things that can most easily be changed then when an event like a bridge closure happens are:

First, the transport services that are provided. This could be extra bus or rail services or the provision of dedicated lanes for buses or goods vehicles an extra 11000 bus seats and 6500 rail seats are being provided in Edinburgh for example. However, this is not likely to match up to the numbers of people that would normally be on the roads, nor are the stations and car parks ready to cope with a big surge in demand.

Second, there is a good deal more temporal and social flexibility in the system than is typically recognised. Recent research studying disruptions found that for disruptions of up to a week people were as likely to postpone and rearrange trips as to cancel them and would also ask colleagues to assist with work trips, family or neighbours to swap caring trips and would shop in new locations. Leaving early and leaving later are both significant options for most people although flexibility can depend on personal circumstances with, for example, single parents having less leeway.

Third, is a rearrangement of the activities which we are all travelling to take part in. This is critical to unlocking workplace flexibility, whether it is timing of shifts, tolerance of lateness or encouraging working from home but can apply to other activities too.

In order for society to keep functioning, the main responses have to be those of social adaptation. If this seems a bit nanny state in its tone then we should look to the success of the travel demand management strategies put in place for the London Olympics and Glasgow Commonwealth Games. In both cities significant efforts were made to adapt transport services but this only worked when combined with business adaptation and the flexibility shown by commuters.  The capacity for social adaptation however, needs to be developed and cannot simply be turned on and off like a tap. It is much easier to take options which you are already familiar with some of the time and those that already use more than one way of getting to work are better able to adapt. The good news is that two-thirds of people already use more than one means of transport each week. 

So, as well as turning to the engineering solution to issues of transport resilience we should also heed the social adaptation lessons of these events and make it easier for people to be more multi-modal more of the time. As a society we will be more resilient to a range of problems if we foster a future where everyone is a little less dependent on their cars and a little better equipped to manage without them, at least some of the time. Such an approach would also help tackle our weekly congestion problems, long-term climate change obligations and obesity crisis in ways which suring up our infrastructure will not.

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