The Anonymous Widower

When Do Mark 3 Coaches Accept The Inevitable?

What Is A Mark 3 Coach?

This is a preamble to the main post, but if it is not included, you won’t understand a remarkable engineering story about how a nearly fifty-year-old British Rail design lies at the heart of the plans for an upgraded train service on one of the UK’s most important rail lines.

The Wikipedia entry for the British Rail Mark 3 Coach , starts with these two paragraphs.

The British Rail Mark 3 is a type of passenger carriage developed in response to growing competition from airlines and the car in the 1960s. A variant of the Mark 3 became the rolling stock for the High Speed Train (HST).

Originally conceived as locomotive-hauled coaching stock, the first coaches built were for the prototype HST in 1972. Production coaches entered service between 1975 and 1988, and multiple-unit designs based on the Mark 3 bodyshell continued to be built until the early 1990s. The Mark 3 and its derivatives are widely recognised as a safe and reliable design, and most of the surviving fleet is still in revenue service on the British railway network in 2016.

The Mark 3 coach is of an older age.

• The structure was reputedly designed by traditional methods without computer.
• Salford University Engineering Department did a finite-element structural analysis on the structure a few years ago and gave it a very good rating.
• The coaches have a full monocoque construction with an all-welded mild steel stressed skin rather than aluminium.
• Many engineers and passengers feel that it is one of the best-riding coaches in the world.
• The coaches have a reputation for exceptional strength and crash-worthiness, which was proven in the Oxshott A244 Bridge Incident, where a 24 tonne cement mixer lorry, fell fifty metres directly onto a Mark 3-based Class 455 train, without any fatalities.

But in some ways though the trains most worthy characteristic, is that train refurbishment companies and their engineers can convert them to any passenger or traction specification, that an operator wants.

The Mark 3 may only be a humble railway coach, but it is one of the world’s great engineering designs.

First and MTR Take South Western

The front cover of the May 2017 Edition of Modern Railways has the usual variety of headlines to grab the atrtention of passing browsers in station newagents.

The main headline is First and MTR Take South Western with underneath it two sub-headlines of Plastic Pigs For Portsmouth and Brand New 707s Swept Out.

Further down, there  is another headline of New Stock Bonanza.

Bringing Back The Class 442 Trains

Between the various headlines, is a picture, not of one of the new trains, but of one of the plastic pigs. It should be said, that this is the nickname for the Class 442 trains, built by British Rail way back in the late 1980s.

The Class 442 trains were originally built to serve the routes to Weymouth and in some ways they are the ultimate Mark 3-based design. They have proper sliding external doors, that meet all the regulations. This is an extract from Description in the Wikipedia entry for the Class 442 train.

As was common on the British Rail Southern Region, many electrical components – including traction motors and electrical control gear – were salvaged from the Class 432 units they replaced. For this reason the older 4REP and 4TC units had to be withdrawn before their replacements were built.

The Class 442 was one of the first types to make extensive use of plastics in construction, and earned the nickname among staff and rail enthusiasts of “Pigs” or “Piggies”. When they were first introduced the units were plagued by minor technical failures, but they have subsequently become among the most reliable EMUs operating in the UK

With this attitude to saving money, how did anything good ever get built?

I’ve only ever ridden in a Class 442 train once and that was to Gatwick Airport a few years ago. Using the trains on the Gatwick Express was a mistake, as the trains were not friendly to airport passengers, as the luggage space was totally inadequate.

London To Portsmouth In Class 442 Trains

But now South Western Railway are bringing the Class 442 trains back into service between London and Portsmouth.

The May 2017 Edition of Modern Railways says this about the reintroduction of the trains, under a sub-heading of Plastic Pigs’ Revenge.

The Class 442 EMUs built by British Rail for the Bournemouth-Poole-Weymouth electrification in 1988, are to be upgraded, including replacement traction equipment.

The article also mentions that on a demonstration run in April 1988, a Class 442 train claimed a world record of 108 mph for a third-rail train.

Currently, services between London and Portsmouth take the following times.

• London to Portsmouth – Fast – one hour thirty-three minutes with seven stops
• London to Portsmouth – Slow – two hours nine minutes with fourteen stops
• Portsmouth to London – Fast – one hour forty-two minutes with seven stops
• Portsmouth to London – Slow – two hours eight minutes with fourteen stops

With those journey times, I shouldn’t think that it is the easiest route to schedule given the amount of traffic at the London end of the route.

According to Modern Railways, there is an aim to save five minutes on fast services and seven minutes on slower ones.

Could this actually make the scheduling problem easier?

A fast return journey currently takes three hours fifteen minutes plus, whatever it takes to turn the train at both ends of the route. I think that this is a variable amount and is adjusted according to time of day. So knocking ten minutes off the return journey might well enable the turn-round times to be more even and create a more passenger-friendly timetable.

So how will these time savings be achieved?

Upgrading The Class 442 Trains

As I said earlier, Modern Railways are saying that the traction equipment is being replaced.

Seeing that the current traction equipment for a Class 442 train,came from a Class 432 train, which were built in the mid-1960s, I suspect the current design may be reliable, but could be improved upon, with respect to power and electrical efficiency.

The very least we will see will be new traction motors and control systems, with the probable addition of regenerative braking, where the traction motors generate electricity to slow the train.

Note.

1. The current Class 442 trains do not have regenerative braking, so a lot of energy is wasted.
2. The Class 444 trains which work from London to Portsmouth have regenerative braking, so obviously the track can handle the reverse currents.

So if nothing else, a new traction package which included regenerative braking, would make a sensible saving in electricity.

I suspect, there are engineers in one of the companies that specialise in upgrading traction packages, working to create the ultimate traction package for the Class 442 train. It would deliver.

• Fast acceleration and braking consistent with what is acceptable to passengers.
• Regenerative braking.
• Minimum energy usage.

Some might think a pantograph for 25 KVAC should be fitted, but I think the train is being modified to be a pure and simple; Pompey Rocket. The transformer to allow dual-voltage working would add weight and would rarely be needed.

A Train With An Engine In The Middle

The Class 442 train is unusual in that it only has one powered car and that is the piggie in the middle of each five-car train.

In A Train With The Engine In The Middle, I described the Stadler GTW, which is a three-car train, with one passenger car either side of a power module.

Wikipedia says this under Description for the Stadler GTW.

Although the traction is good for the powered bogies the concept has the same problem as other light railcars with the brakes on the non-powered axles having lower grip than traditional railcars. This has led to actual restrictions when leafs are on the rails as the wheel slide protection can not fully compensate the effect. The central power module has limits with heat dissipation as well which can lead into situations where the power output needs to be limited which is automatically done in this construction concept.

Perhaps because it is a heavier train, the Class 442 trains doesn’t have these problems!

I also have personal memory from about 1970.

At the time, I worked in simulation at ICI Plastics in Welwyn Garden City. I remember reading how British Rail Research at Derby had applied their analogue computer and dynamic modelling skills to the problems of why so many four-wheel freight wagons were derailing. They solved that problem and I have a feeling the work influenced the design of the running gear of the Mark 3 coach.

Could the unusual concept of the powered middle car of five have been influenced by all the research?

Incidentally, five-car Electrostars like Class 377 and Class 378 have unpowered middle cars, with most of the others powered.

Comparing power of a five-car 100 mph Class 442 train with a five-car 100 mph Class 377 train and they both have traction motors rated at a total of 1200 kW. The 442 weighs in at 199.54 long tons, as opposed to the 170.9 long tons of the Class 377 train, so it could appear that the modern train has faster acceleration.

The Class 442 Train And The High Speed Train Compared

By comparison, Wikipedia quotes the at rail power of a Class 43 locomotive as 1,320 kW.

Obviously, it was a deliberate design to put the motored car of the Class 442 train in the middle. But was it also, so that when working as a pair, you had two powerful power cars at 54 long tons separated by four lighter, but very stiff Mark 3 cars at between 35-39 long tons?

After all by the mid-1980s, British Rail had a lot of experience of running Mark 3 coaches between two powerful Class 43 locomotives, in the High Speed Train.

Surprisingly, the Class 43 locomotive is only 15 long tons heavier than the Class 442 motored car.

So could the Class 442 train be considered an electric HST, with a couple of extra cars at each end?

The dynamics could be similar and I suspect British Rail knew the dynamics of Mark 3 coaches and locomotives well.

After all, a few years later High Speed Trains on the East Coast were lengthened from 2+8 to 2+9, with it appears few problems.

The Ease Of A Power Upgrade

Upgrading the power on a Class 442 train could be easier than some.

• All the power systems, except for the current collection, are in piggie numbered three in the middle.
• Changes will be needed in the driver’s cabs, but I suspect that most changes in the rest of the train will be purely cosmetic and for the ease of passengers and crew.
• The interior layout of the powered car has been chopped and changed many times, so it could be rebuilt to see the trains to their final retirement.
• Engineers have plenty of space in which to work.
• The upgrade would be more like updating a locomotive than an electric multiple unit.

I doubt it would be a very high cost upgrade, but the budget won’t need to be small, as an alternative fleet of eighteen 100 mph trains wouldn’t come cheap.

I suspect too, that in the rebuilt power car, no technology that helps the train meet the required performance, will be ruled out on grounds of cost.

Will The Upgrade Include A Battery?

I just wonder, whether onboard energy storage features in the engineers’ thinking?

This page on the Southern Electric Group website, shows a series of side views of the motored car. It would be interesting to see if a battery about the size of the 75 KwH unit in a Routemaster bus could be squeezed underneath.

Suppose the energy generated by the regenerative braking whilst stopping, were to be stored in such a battery.

This would mean.

• Braking energy could be used to accelerate the train after the stop.
• Less energy would need to be transferred from the train using the third-rail.
• Electricity would be saved.
• The train would have a short range on battery power.

In the Wikipedia entry for the Portsmouth Direct Line, there is a section called Topography Of The Line. This is said.

The central part of the route, from Guildford to Havant, runs through relatively thinly populated country. The line was designed on the “undulating principle”; that is, successive relatively steep gradients were accepted to reduce construction cost. In the days of steam operation this made the route difficult for enginemen.

Leaving the Southampton main line at Woking, the line diverges southwards falling to Worplesden and then climbing to Guildford, using the River Wey valley. After gentle gradients, the line then climbs from Godalming for eight miles (13 km) at 1:80/1:82 to a summit near Haslemere; it then falls at 1 in 100, climbing briefly at Liphook and then falling at 1 in 80 to Liss. A second climb of three miles (5 km) follows to a summit at Buriton Tunnel, then falling at 1 in 80 and then more gently for 8 miles (13 km) to Havant.

I’m sure that extensive modelling of the Portsmouth Direct Line has been done and it has been investigated whether a small amount of energy storage would be useful in assisting performance and saving electricity.

Will These Modifications Produce The Proposed Timings?

The upgraded Class 442 trains will probably be able to execute a stop at a station in a shorter time than the current Class 444 trains.

On the slow services, South Western Railway is aiming for a saving of seven minutes on a journey with fourteen stops, or a saving of just thirty seconds a stop.

I also suspect that services on the challenging Portsmouth Direct Line would be helped with a modern traction package and South Western Railway’s goal of a five minute saving is possible, especially as the seven stops might give three and a half minutes.

Conclusion

I suspect that someone will come up with a very innovative traction package.

The inevitable retirement could be a lot of years away yet!

April 30, 2017 Posted by AnonW | Transport/Travel | Class 442 Train, Class 455 Train, Mark 3 Coach, South Western Railway | 5 Comments