It is good news that the railway to Leven is nearer to being reopened and your editorial on the need for a railway revival (9 August) was timely. It is sobering to realise that some 70% of the land mass north of the central belt is dependent on just two railway lines: at the Forth Bridge and at Larbert which you call "choke points" A Christmas derailment at Dundee some four years ago blocked the line and cut off Aberdeen by rail from the south for three days.

The Climate Emergency has now been recognised by the Scottish Government and more sustainable means of transport are to be prioritised. A more resilient rail network must be high up that list both for passengers and for freight.

There are five possible rail routes between Edinburgh and Glasgow. All are electrified and three remained open when the Winchburgh tunnel was closed due to flooding. Further north, there is no electrification. Perth has a good rail connection with Glasgow but a very poor one with Edinburgh (via Newburgh) because the direct line through Kinross was closed to make way for the M90 motorway. Building a new direct line between Cowdenbeath and Perth using some of the old track-bed would reduce the journey time from Edinburgh to Perth (and on to the Highlands) by 30 minutes.

Similarly, recreating a line from Perth to Laurencekirk via Forfar would give a second option to Aberdeen from the south to increase resilience. These are for the future, as you say, but they would also give much more scope for the sustainable railfreight option which the shortage of HGV drivers and the Climate Emergency requires.

More immediately, the Government aspirations to double track and electrify all the lines between the seven Scottish cities have only been progressing slowly. Greater capacity and speed on the Highland Main Line (HML) and between Aberdeen and Inverness were priorities 3 and 4 (after the Queensferry Crossing and EGIP) in the Strategic Transport Priorities Review of December 2008. We should have the doubling of the first 16 miles out of Aberdeen to Inverurie completed later this month, but both lines are over 100 miles long and the usual summer overcrowding and delays on the HML between Perth and Inverness have been as bad as ever this year.

There is a lot to do yet to underpin the Scottish economy with what you call the "21st century railway revival."

EGIP - Edinburgh-Glasgow Improvement Project [which included electrification to Stirling, Alloa and Dunblane also] was completed in March 2019.

I agree with your observations. Creating more diversion routes would certainly help. In addition, I think that the resilience of existing operations (against flooding, train failure, signal problems, etc) should be far better than it is at the moment.

Short turn-around times and lack of spare capacity in every aspect of operations combine to create a situation where a single relatively small problem early in the day can produce an avalanche of disruption across the country that last for the rest of the day.

Unfortunately, building-in resilience does not seem to be compatible with a railway that is run primarily for profit. Spare trains, crews, equipment, and timetable slots are expensive and promise little or no return on investment.

Another factor that works against resilience is the increasing complexity of all the interlinked systems that make up a railway. Even a train toilet these days seems to have more sensors and microprocessors than an Apollo space mission. The result is that when something stops working there is unlikely to be a simple fix that gets things moving - or flushing - again.

And finally, there can be an embarrassing lack of foresight in the design of equipment: a recent, relatively short power cut across England paralysed entire fleets of electric trains. It turned out that Siemens-built Class 700 and Class 717 could only be restarted with the help of a technician, because on-board computer systems could not be rebooted by the driver.

How to improve resilience? I'm sure that lessons are learned in cases like that power cut. It may also be possible to include more requirements for resilience in the franchises for train operators. Ultimately I feel that resilience should be a matter of people taking pride in their operation at all levels, and of creating a culture in which issues are flagged-up and addressed before they become big enough to cause outrage in the news media.