Thinking Long Term: Learning from the Railways

This post is part of a series inspired by the book "Sustainable Infrastructure: Principles into Practice" (see the introduction to the series here). Having examined the issue of intergenerational stewardship and thinking long term about infrastructure (Principle 3) in my last post, how can we put this knowledge into practice in real civil engineering situations such as the railways?

Putting it into Practice 3.1: Plan for the Long Term

There is a need for future proofing, but all our predictions are scenarios: we need a clear statement for each line of what it would ideally look like in 20 years time, such that all projects work together to either facilitate the vision, or at the very least not get in the way. For example, the Harrogate Line was reduced from two tracks to one between Poppleton and Hammerton in the early 1970s, which means that it is now only possible to run one train per hour between York and Harrogate and any delays quickly escalate because the train in one direction can't pass a train which is running late in the other direction, so only 85% of trains run on time. 

There are plans to upgrade and electrify the line, but two major constraints have been imposed by short-sighted bridge construction since that time: one bridge (A1237) is too low for electrification, particularly with the adjacent level crossing leading to the Millfield Lane industrial estate (wires have to be higher at level crossings to allow lorries to pass underneath). A second bridge (where the A59 crosses the railway the Red Lion Inn) is too narrow to restore the second track between Hammerton and Poppleton. The cost of closing the roads to replace these two bridges is prohibitive. 

This story illustrates the need for long term planning, with a horizon of 20 to 50 years. Making "passive provision" for future improvements to the rail network is a hallmark of good practice, but there's a problem: it costs more, and those costs are not borne by the railway but the county council who are responsible for local road bridges. If someone came to you and asked you to spend an extra £1m of public money making your new bridge wider or higher on the basis of improvements not currently funded and which might never happen, you might well look at them askance. 

But this is the fundamental challenge of thinking for the long term: your bridge or building will be there for decades, so it had better cope with expected changes in traffic and its surroundings over its design life unless you want to knock it down and rebuild it in 15 years' time. And you need the political will to do the right thing for the long term, considering the whole life cost of getting it wrong. That's what the ICE's Commit to Infrastructure campaign is all about: calling on decision makers from all political parties to be visionary, bold and genuinely engage with the public to build trust, confidence and credibility into the decision making process.

This approach was a major strength when building the Manchester Metrolink because new tram routes were able to use several former railway cuttings which had been closed by Beeching, but the routes were protected in the local plan. Some were used as footpaths and cycleways, while planning conditions required that no-one could build over the route unless they made provision for future reuse as a railway (on the Didsbury line, there is a large development built over the line with a concrete tunnel structure beneath: all the Metrolink had to do was excavate the infill material and install the tram lines). 

In summary, long term planning for infrastructure needs to include:

• Imagining what the surrounding world will be like, within which our infrastructure will work.
• Deciding what what existing or changed characteristics the infrastructure must have (eg will it be electrified? Must it be decarbonised?)
• Estimating how the changes in these two items will interact with each other, to determine actual demand, use and impact (good and bad).

The problem is, traditional methods of forecasting and risk analysis tend to assume that the future will be similar to the past. We know that with climate change, changing population and demographics and rising energy costs, the future will not (and must not) be like the past! So we need to start using different tools such as scenario planning, foresighting and visioning to understand the range of situations our infrastructure may need to cope with during its design life. I'll be covering some of these tools in later posts on this topic.

The key principle is to plan long term, using the right tools and questions to explore where you want to go, and to identify the real uncertainties that may exist. Then you can structure your strategy or project scoping to minimise the risks.  

Reference:

Sustainable Infrastructure: Principles into Practice, Charles Ainger and Richard Fenner, ICE Publishing, 2014

See also

• Railway Tales
• Making a difference on Metrolink
• Planning for the long term: Why doing it for the kids isn't good enough