Train operating company Southern hasn’t had a great time of it recently. Countless tales of woe relating to delays, staff shortages and cancellations have led to industrial action and much gnashing of commuter teeth. Big wigs have appeared before parliamentary committees; new transport secretary Chris Grayling has declared that sorting out this mess would be his top priority. If Southern was a person living in the 18th century, it would surely be ripe for putting in the stocks and receiving a good flogging.

Or would it?

To be sure, Southern does deserve chastisement for the whole “staff shortages” fiasco – but there are other underlying causes seemingly outside of Southern’s control. This means that it only takes one or two extra problems – such as driver shortages – to throw things into a tailspin.

Here are three such underlying issues that Southern has to contend with – as would any other operator that might take over from it.

1. Network design

The Southern network map appears to have little rhyme or reason. Services run from Milton Keynes, through West London into Clapham Junction, down through various parts South and South West London before continuing further south into Surrey, Sussex and Kent.

The network was constructed by many different private companies, who didn’t put much thought into how their respective services would integrate with one another. As a result, there are numerous complex flat junctions – places where trains must cross each other’s paths – and bottlenecks at various points in the network.

This is bad, for two reasons. Firstly, it limits the speed and frequency at which trains can run (because otherwise they’ll bang into other trains). Secondly, it increases the risk of infrastructure – in the form of points – simply failing.

Southern didn’t actually design and build the network, and so is not really responsible for any of this. Indeed, Southern is merely a brand name of the not-so-catchily named “Govia Thameslink Railway Ltd.” which operates the trains (actually, it doesn’t even own them, but leases them). One could change the operator until the cows came home; they’d still be stuck with the same awkwardly designed network.

2. Demand

Everyone and his wife wants to live in London and the South East. That means increasing demand on the region’s railways. And, as demand has increased, so has the frequency of trains to meet it.

This is, theoretically, a good thing. But a lot of the Southern rail network runs on double tracks, as opposed to quadruple track more common on other networks; and high frequencies do not mix well with limited track capacity. Such tight running of services, combined with all those flat junctions and bottlenecks, means that even a relatively small delay on one service can have massive knock on effects, causing delays elsewhere on the network.

Furthermore, high demand means an increase (or a risk of an increase) in dwell time at each station. When a peak Victoria bound packed train arrives into Streatham at 7:50am, commuters have to wrestle their way off the train just as others are trying to wrestle their way on.

In short, high demand increases the likelihood of increased dwell times, which increases the likelihood your train will be delayed – and that this delay will have a knock on effects for other services.

For sure, Southern should be recruiting and training more drivers to provide its original timetabled service. But even with a full complement of drivers, the complexity of the network, plus the high demand and all the difficulties that brings, mean that the likelihood of delays is unlikely to change with a different operator.

3. It’s the infrastructure, stupid

There’s a limit to what Southern can do to fix these problems: train operators don’t actually own or run the infrastructure (track, signalling, and so on) that their leased trains run on.

UK rail infrastructure is actually owned, run and maintained by Network Rail, an arms-length publicly owned body. The recent track fire at Gatwick Airport station, for instance, was caused by a power supply problem which had nothing to do with operator Gatwick Express (another brand part of the Govia monolith), but was instead under the auspices of Network Rail.

The stats show that around two third of Southern’s delays are caused by factors not under the control of the operator. A new operator won’t have any more influence over the infrastructure than Southern does. And so, delays of some kind will probably still persist.

Sorry about that.

The problems outlined above suggest that a change in operator won’t be enough to fix all the problems on the network: rather, it’ll take significant investment. Sorting out those devious flat junctions and introducing more quadruple tracking might be a good start.

But this work will be far from straightforward. Firstly, projects of this nature tend to be really complex and take a loooong time. The Thameslink programme for instance, was once known as “Thameslink 2000”. It’s due to finally be completed in 2018.

Finding the space might be difficult, too. A lot of the land up right to the tracks on the Southern network has been sold and redeveloped. Viaducts and tunnels can be built – but these can be expensive, noisy and visually problematic.

Oh, and all of this stuff is really expensive, and there might not be the money anyway.

Happy times.

Want more of this stuff? Follow CityMetric on Twitter or Facebook.