Wednesday, 4 October 2017

The Gibb Report - An Assessment

There has been a lot of public and political frustration concerning the problems of Southern Railway and the Govia Thameslink Railway, so the British Government decided to commission Chris Gibb, a well-known and respected railway manager, to investigate the causes of the problems with the train service. The report was published on 22 June 2017.

I have carried out an assessment of the Gibb Report and I presented a lecture on my assessment on 3rd October 2017 at the University of Birmingham as one of their series of Prestige Lectures. More information on future lectures is available here:

A copy of my paper on the Gibb Report is available here:

The Gibb Report - An Assessment.

Sunday, 28 May 2017

British Airways Computer Crash

It is very alarming that the British Airways computer crash on Saturday 27th May 2017 shut down its entire operation. Apparently it was due to a power failure. That there was no back up power supply or UPS (Uninterruptible Power Supply) as it is called, is remarkable. That a major international transport system, with a world wide network of routes, can run its operation on a single, interconnected system technology without any backup system, demonstrates a serious lack of management responsibility. And, it has serious implications for the railway industry.

Normally a vital operation will have a some sort of back up or UPS to provide business continuity. But, consider this: if a system is vital and safety related, it needs to have a UPS. This will come into action when the main power system fails so that the operation keeps going. However, there is a trend nowadays that says, "If the UPS isn't available, the main system shouldn't be allowed to start up." And, "If the UPS fails, the main system must be shut down because it doesn't have a working backup." This is crazy. If this is your designer's philosophy, then you don't need a backup because it will eventually shut down your operation whenever it fails.

Railway signalling and train control systems are going the same way.

Saturday, 13 May 2017

Cyber Attacks

With all the news on cyber attacks around the world, this article from London Reconnections is worth a read: You Hacked. It looks at some attacks that have been carried out on railway systems and offers a warning.

Friday, 12 May 2017

Braking Curve

In railway engineering, you will sometimes hear talk of a "braking curve", often in connection with train performance, platform re-occupation times or signalling. We use a braking curve to calculate how long it will take a train to stop from a given speed. It can be used to determine both service and emergency braking distances. It can also give braking times, if needed. Here we look briefly at the braking curve and what it means.

The braking curve is the shape formed on a speed/distance chart by a train as it slows down from normal speed to a stop.  A typical curve looks like this:

The curve begins when the driver applies the brake. The brake system take a few seconds to build up to the required braking rate (the "feed up" time) and then the train begins to slow down.

With a constant brake demand, as selected by the driver, the train slows down more rapidly as the speed falls. This is because, at the lower speed, the train has less energy to dispose of. If the brake is left on at the same level all through the stop, eventually the curve will get steeper and steeper until it ends vertically at the stop. If this is allowed to happen, the train will stop with a sharp bump and a lot of coffee will be spilt. To prevent it, a skilled driver will ease off the brake as the speed falls and this will allow him to stop the train gently. The effect of this can be seen on our curve as it nears the stopping point.

Our drawing also shows an "equivalent straight line" curve. This is a simple way of showing the stopping distance that we can expect a train to cover, given an equivalent deceleration rate. It can be used to calculate stopping distances for approximate signalling calculations, for example, although today, computer programs make accurate and detailed calculations simple. The straight line braking curve can used, for example, for outline planning or to demonstrate principles.

Report on Rail Franchising in Britain

A report on railway franchising in Britain was published in early May 2017, 'Ensuring a Sustainable Rail Industry - Options for developing franchised passenger services', published by the Campaign for Better Transport. It is an interesting read, partly because it has some useful statistics about rail travel, franchise operations and passenger attitudes and partly because it tries to generate debate on the industry and the way in which it is run.

The report notes that passenger "trust" in the railway is falling and it suggests that this is causing, in part at least, a slowdown in the increase in traffic seen over the last 20 years. It also suggests that the issue is partly due to the franchising model itself, which doesn't encourage quality.

There is also justified criticism of the complexity of the fares systems and the difficulties that they present to passengers. I do not understand why we can't have contactless ticketing across the country.

There are some omissions:

  • There is no mention of staffing problems and the recent series of politically driven strikes;
  • There is no realisation that the capacity constraints that are causing a fall in punctuality;
  • There is no mention of the responsibilities of Network Rail in the performance model;
  • There is no understanding that the British, as a nation, generally deride the public transport system;
  • There is a mistaken belief that what has been done on one railway can be applied to any other one with the same results. 
The value in the report is the generation of discussion on the performance of franchised railway operation. It is worth a read.

Friday, 5 May 2017

Railway Technical Website Update

We are modernising the Railway Technical Website. There is a new look and new pages. Many pages are being updated. We are gradually archiving the old pages where they are likely to be useful.

While we will try to get everything in place correctly as we update each page, there are bound to be some minor teething problems. Please let us know if you find any errors we have missed.

Thank you for visiting us and for your understanding during our modernisation programme.

Friday, 23 January 2015

Vivarail D-Train Diesels?

D Stock
There has been much publicity recently about a company called Vivarail that has been set up to buy redundant London Underground (LU) electric rolling stock and convert it to diesel-electric operation. The idea is to use the converted stock on various routes currently suffering from rolling stock shortages or where the outmoded and much-hated, bus-style "Pacers" are still used.

The LU trains are officially referred to as "D78 Stock"; the D being the District line where they are used and 78, the year of their order. Everyone calls them "D Stock". Your author is quite familiar with them, having written much of the original instruction material for the stock and then doing much of the original training of its maintenance staff.

Fleet Size
The Underground's D Stock fleet consists of 75 x 6-car trains, with each train made up of two 3-car units. The standard formation is arranged so that driving cabs are only provided at the ends of the train, so each of the units is "single-ended". The inner end of the unit couples to the inner end of another unit facing the other way round.  This means that you need an even number of units of each type to make up complete sets of trains. Some units are "double-ended", i.e they have a cab at each end so that, in the event of a shortage of either type of single-ended unit, a double-ended unit can be used to replace it.

There are 65 west facing single-ended 3-car units and 65 east facing 3-car units. There are 20 double-ended 3-car units. The publicity says that Vivarail have purchased enough cars to make up 75 units in 2-car or 3-car formation. Vivarail themselves suggest 4-car units are possible.

Vivarail are calling their converted trains "D-Train". The D-Train concept proposes using the original car body (suitably modified) and the existing bogies and their traction motors. Each driving car will be equipped with two 200 h.p. 3.2 litre diesel engines. Each engine will drive an alternator to provide electric power for the two traction motors on each bogie. Presumably, the auxiliary power will be derived in the same way. Of course, there aren't many details at this stage, but there are lots of unanswered questions. Here are some to whet your appetite.

Top Speed
This is set at 60mph. A Pacer can do 75mph and Class 170 will do 100mph. The modelling results published so far suggest a 4% increase in timings as a result. Not too bad but it could get worse for a heavily loaded train with long station stops. Only two of the existing doorways per car side will be used so the dwell times will be similar to the existing.

A D Stock car weighs 30t. A pair of diesel engines and their alternators will be heavier than the existing PCM traction equipment. I expect the weight of the motor car to go up by 5-7 tonnes. How a weight increase of over 20% will affect the bogie and ride performance is anyone's guess. Both suspension systems are solid rubber. Speaking of weight, I'm wondering where they will put the batteries. They are currently under the passenger seats but they will need a better spec for the D-Train.

This is a big concern. Two underfloor diesel engines, operating independently will generate a lot of vibration and noise and this will require serious research and substantial mitigation. There is also the question of the car body harmonics and how these will be affected.

Air Conditioning
There is no mention of air conditioning. It will be a passenger expectation that modern or upgraded trains will have it. Not to will be a significant omission. To fit this to the D Stock passenger saloon would require significant modification to the roof. The space along the ceiling would quickly get filled up with ducting and fan units.

The 3-car trains will have a trailer car between two motor cars and this is where the toilet will have to go. There is no room for the waste retention tank under the motor cars. Two-car units will not be able to have toilets. My own feeling is that all the trains should be 3-car sets. This offers flexibility and consistent performance. Also, these cars are 15% shorter than a Pacer, so they wouldn't have much capacity in 2-car format.

Cab Controls
The LU cab is completely different from what's seen on main line trains and it will be necessary to strip out the existing console and replace it with a new one. The LU driver's safety device (DSD) is in the controller handle, so there is no DSD pedal. That will have to be added. The desk displays and controls are completely different and there are no CCTV or computer screens in the cab so these will have to be added for Driver Only Operation (DOO).

Cab Doors
The cab has four doors. These are a nightmare for draughts. I would expect to see the front door (M Door) sealed closed and some serious draught proofing put in for the side doors. There are no drop-down windows. Fitting them might give problems for the door opening pocket. It will increase the draught proofing requirements.

I can't imagine these trains being accepted without DOO already fitted. For a modern train, you need bodyside cameras and in-cab CCTV. The LU system for DOO (they call it One Person Operation (OPO)) is based on platform-mounted equipment so the D-Trains will need the on-board systems added. This is not as simple as it sounds and it needs to be integrated with the cab console design.

It would be silly not to equip the outer ends of units with automatic couplers but I suspect the LU type would not be suitable. It will be desirable to have longer trains on some routes and flexibility should be maximised. However, auto-couplers are not cheap and there maybe some difficult engineering to do to the ends of units to enable them to be fitted.

Always a difficult issue. In 2013, Angel Trains re-engineered a 4-car Class 317 EMU with a new traction system and quoted a cost of £7million; that's £1.75million per car but it's a prototype, so there's lots of development costs in there too. Let's say Vivarail can get orders for 70 x 3-car units. This is 210 cars, a reasonable production run so, allowing for development and financing costs, there is probably a good business case if the cost per vehicle can be kept below £1million for a 20-year life. As always, the big risks are the technical unknown unknowns.

There's lots of other detailed stuff but this article gives a flavour for what's involved. I am sure that the Vivarail team, led by the very experienced railway manager Adrian Shooter, are familiar with all the pitfalls of train refurbishment but for those readers who aren't, I wrote about it a couple of years ago:
It is based on real life experience.