All you wanted to know about how railway rolling stock is designed, manufactured, assembled, tested and shipped but were afraid to ask. Most of this page was written by Paul Berkley, who also supplied many of the photographs, and it was then edited with additional material from Nick Cory.
The Process - Timescales - Design - Long Lead Ordering - Jigs and Tools - Manufacturing Engineering -Configuration Control - Production Control - Materials and Equipment Buying - Parts Manufacture -Underframe - Sides - Bodyshell Assembly - Underframe Invert - Painting - Roof - Ends - Transport - Bogie Construction - Wheels and Axles - Bogie Assembly - Wiring - Piping - Fitting Out - Testing - Commissioning -Delivery.
railway rolling stock manufacturing consists of a series of stages which begin with the signing of an order and culminate in the entry into service of a new train. These stages consist of signing the contract, doing the design, ordering materials and parts, manufacturing and assembly, testing and delivery. It is a costly and time consuming business and there is a lot of risk in the process because a lot can go wrong. Apart from the technical difficulties of designing and building a complex, multi-million dollar project, everyone wants to play trains and interfere with the design, especially politicians and newspaper editors, both of whom have one thing in common - they know nothing about railways.
So you want to buy a new train or diesel locomotive? How long will it be before it is carrying passengers or hauling cars? Well, give yourself four years from the date you decide to buy. It can be done more quickly - a new locomotive order in the UK was once famous for having its first loco delivered 18 months after contract signing - but 3 or 4 years is more usual. Here, I am assuming that it is a new design, not a run-on order and that there will be over 80 new vehicles. I am also assuming that you know how many trains or locomotives you need and what the general basic design will need to be. The procurement process will occupy at least a year - longer if you need finance from the commercial market. For some information on costs and financing, try the Railway Finance page on this site.
So let's say you give the supplier Notice To Proceed (NTP) a year after you go to market. The design process will have already begun, since the supplier will have prepared a concept design as part of the bidding process. By the time he gets NTP, he will have got to a stage with his customer where he knows he is the preferred bidder and he will have started more detailed basic design work.
Six months after NTP, parts manufacture will start and, six months after that the first body might be ready for installation of its equipment and interior finishes. Give it another year for completion of equipping and a lot of testing before it is ready for shipping. Three years have gone already and the first car has still only just rolled out of the factory door. Acceptance testing on site and bureaucratic approvals may last months (at least a year in the UK) before the train finally enters service. There is some slack in this broad outline because I am sure there will be technical problems on the way but we have used up our four years. Locomotives may take less as each one can operate as a unit and isn't dependent on other vehicles like an EMU (Electric Multiple Unit).
This is where it all begins. Design work starts during the bidding process. The customer will issue an "invitation to tender" (ITT) and then wait for the rush. Rush? Well, not quite. It starts with the supplier producing an outline design, which is prepared against the ITT and then costed. These days, most manufacturers have created their own catalogue of vehicles that they would like to sell because they can build to pre-existing designs and offer them at a more competitive price. The designs are offered in modular form so they can be customised to suit the buyer's needs. Unfortunately, a contract (particularly one procured by a publicly-funded administration) is rarely as simple as this and, usually, the potential customer will have produced a specification that he wants his vehicle designed to. Invariably, this will not fit conveniently into the little niche of standard designs that the supplier hoped it would. Of course, this puts the price up. Many customers are now trying to procure through performance specifications, where the dimensions, capacity, speed, power requirements and reliability are specified rather than details like the make of door engines or colour of the upholstery for the driver's seat. This gives the supplier the chance to adopt standardisation in many areas, but many customers still fall into the trap of asking for a bespoke train and then wondering why it is so expensive.
Now, let us assume that the preliminary design was accepted, a price agreed and a contract awarded. The engineering design office (henceforth referred to as the DO - originally short for drawing office) will now swing into action and start developing a plan for the design work of the railway rolling stock, which will include producing a Bill of Materials (BoM) that will identify all the details necessary to manufacture the vehicle. A preliminary list of drawings will be tied in with the BoM and there will probably be in excess of 3000 drawings needed. Meetings will be held with the purchasing and production departments to determine priorities for preparation of designs.
During the bidding phase, the DO will contact various sub-suppliers of brakes, lighting, seats, propulsion, traction motors etc. about the specifications, to determine who can, or is willing to meet the performance requirements. If you look at a piece of rolling stock, it is easy to see that the supplier is really just an assembler of many parts that are purchased from other suppliers. Perhaps all he has is a specialist shop for manufacture of the car bodyshell and one for the wiring looms, and the rest of the vehicle is bought from someone else. Some car builders, like Brush Traction in the UK, even buy complete locomotive body shells and bogies from external suppliers. However it is done, the vehicle design and assembly concept will eventually come together and some preliminary design drawings will be produced for presentation to the customer.
It is at this point that some long lead items will be ordered. Steel, some types at least, can have a three-month lead time, especially if you want a special finish for an unpainted vehicle. Cables can require a six month lead time, particularly if they are of special fire proof or low toxicity specification. Car interior panels may also require specialist materials with long manufacturing periods. Of course, once you order these things, you are locked into the design, so you'd better be sure you get it right.
Another area which needs to be sorted out early is jigs and tools. The car body parts will have to be assembled in jigs to ensure that they are held rigidly and in the correct position during welding. The body shell itself will also require a large jig to assist in the assembly. Jigs cannot be designed until the body form is known and the construction methods agreed.
A jig is basically either a steel bed, shaped to carry the section to be welded, or it a series of specially formed steel frames, upon which parts will be fixed while they are welded. The jigs will be fitted with adjustable clamps which will hold each piece in its correct position for welding. Jigs come in all shapes and sizes, depending on the part or parts to be assembled and the welding system to be used. Jig design is an art in itself and many a project has been a success or a failure because of the quality, or lack of it, of the jigs.
Underframe assembly in a heavy jig where the solebars and transoms are welded. It is essential to ensure all parts are held to strict limits to prevent distortion during welding.
Bodyside assembly jig. It is shaped to match the body curvature. The panels and their internal strengthening members are held in place by clamps while being welded.
The roofing jig, where the parts are clamped to provide stability during welding. The roof is one of the more difficult parts of the car to weld as it is thin and tends to distort easily.
Some manufacturers have been known to try to cut back on the time or materials allowed for jig design and manufacture. This is always an expensive mistake. If the jigs are not right, the car body won't be right either. It is a sobering thought that, in the last 30 years, every new tube train London Underground has had delivered has not fitted into the tunnels. One fleet had to be rebuilt.
Tools are another important item which can be forgotten. If any specialist tools are required - like dies for stamping steel parts, these must be properly designed and manufactured to the highest standards. Specialist tool makers are best for the job. I have seen shop floors littered with rejected stampings and pressings, thrown out because they were poorly made with bad tools and therefore didn't fit were they were supposed to.
The early design meetings will culminate when the scheduling department produces a Work Breakdown Structure (WBS), which will map out how the vehicle will go through each stage of manufacture and assembly to reach the final steps where it is commissioned and delivered to the eagerly awaiting customer. The WBS will have to match a time plan, the submission of which is invariably part of a contract these days, and which will contain milestones in the design and manufacturing process which the supplier must adhere to. It will also provide convenient packages for the design staff to work within so that drawings for the production process can be issued quickly for the first parts needed for assembly.
If the DO has been lucky, they will find that they are able to get away with only modifying and updating some existing drawings and perhaps, if they are really lucky, only the drawing number will need to be changed. Of course, life is never that simple and there will be panics and much heart searching as new designs have to be developed in the time frame agreed with the customer and with the production control people in the factory.
Once the DO finishes a package (a complete set of drawings for a specific item of manufacture), it is forwarded by a Configuration Control section to the manufacturing engineering department. Configuration control is responsible for ensuring that all the drawings and documents connected with the contract are registered, submitted to the customer for approval, returned from the customer in time (they are often not), questions from the customer are answered, that the latest updates to drawings and instructions are passed to the production control people and all correspondence is noted and archived. It may sound bureaucratic but it is essential if all the paper is to be kept up to date and is retrievable if there is any sort of dispute (and yes, there always is).
Configuration control is also about monitoring the putting together of the vehicle as it gets built - ensuring not just that there are no parts missing but that all the parts fitted are at the correct modification state, both hardware and software (see Version 25 story on this site). The former is difficult because of the slow rate at which hardware faults always seem to get corrected and the latter is even more difficult because of the sheer speed at which programmers emprically try to debug their products, with sometimes chaotic results.
Now the challenge comes: the DO has completed a design package and it is manufacturing engineering's turn to look at what has been produced to see if it can be made. Manufacturing engineering is usually part of a team under the Project Manager who will be ensuring the vehicle is 'coming together', so to speak, and will also include a couple of engineers and draughters to make any changes that are needed. Sometimes it is necessary for the manufacturing department to produce additional drawings that will enable the manufacture to continue without delay. These will be produced in conjunction with the production department.
Production control have the responsibility of bringing all the various procurement and manufacturing areas together and ensuring a completed vehicle comes out of the shop with all the requirements of the customer to the schedule agreed with the customer. To do this, using the BoM we talked about earlier, a schedule will be put together which will show what tasks are to be completed, where, using which machines or tools, when and by whom, in the manufacture of the vehicle. This will show the various work stations, identifying the tasks that will be performed at each station. Production control will also allocate materials, staff and times for each process. Production orders are then produced and passed to the manufacturing shops together with the drawings.
There are all sorts of fancy names for "buying" around nowadays; Purchasing, Procurement, Sourcing, Materials Management and so on, but when it comes down to it, buying is what this department does. A manufacturer usually has one buying department which may be split into two sections - one to buy raw materials, the other to buy complete items of equipment.
The section buying the raw materials will get their orders from the manufacturing department and will be involved in the purchase of bar stock, sheet plate, nuts, bolts, piping, paint and probably such items as welding rods, glues and mastics. Their responsibility will be to ensure sufficient material is available in the machine shops, the fabricating shop or the paint shop to enable parts to be finished to schedule. They have to do this early in the process. We have already seen how some specifications for long lead items will have been agreed and ordered immediately after NTP.
The section buying equipment will, for the most part, have a more difficult job and they will deal mainly with the DO. This is because they will be reliant on the DO providing technical specifications to issue to the various sub-suppliers. Sometimes the customer's specification will dictate whose equipment should be used. This makes it very difficult for the buyer to obtain a competitive price, as the sub-supplier will be aware that their equipment is specified by the customer. In any case, the buyer will be under pressure from the DO to identify a supplier to enable designs to be completed and he can become caught in a vicious circle if he is waiting for the specification from another group within the DO.
Finding three suppliers of say, a braking system, can be a difficult task and, if it is a boom time for orders and the brake manufacturer has a full order book, getting his attention will compound the problem. But the buyer has to find the right product at the right price, so he will find himself in endless discussions and meetings with the salesmen and engineering staff of the supplier. The DO staff will want to meet with the engineers from the supplier to learn about the physical and performance capabilities of the equipment and the buyer will be expected to attend these meetings to make sure the DO does not 'gild the lily' with the product and increase the price out of range of the budget.
The many parts that make up a locomotive or car body shell will be made in a machine shop(s) either at the manufacturer's plant or contracted out to sub-suppliers. These parts may be structural members, ribs, bolsters or panels. It is important that the DO designs parts in such a way that they are easy to make and of materials which can be processed by the factory with its existing equipment. It is also important that the parts can be easily assembled to form the vehicle as it progresses through the manufacturing process. The cost of many vehicles has soared because the design of parts has caused trouble for the assembly process by being too complex, too tight tolerances, or too difficult to handle. Curved shapes are the worst and roofing the most vulnerable to such problems.
Once sufficient parts have been manufactured separately, they are finally brought together for assembly in a jig. The underframe is usually the first part of the bodyshell to be built and its principle parts will include, sole bars, runners, bolsters, and transoms.
An important feature of the manufacture of the underframe is the provision of a camber. This is the 'bowing' of the frame along the longitudinal length upward from the ends to the centre. The camber is important because, as all the other structures are added to the underframe, the weight obviously increases. If there was no camber, the resulting car shell would sag in the middle. To see how this works, look at the trailer of an articulated truck that you see on the road and observe the upward bow.
The vehicle underframe will be moved through a series of jigs designed to hold the frame in specific locations to accomplish attachment of the various components. See the following photos for the various steps in assembly.
Our company will develop three-axis bogies...
CRRC electric's first Public Open Day: technology tour of "Gigafactory"...
Five new maintenance products of the company have successfully passed the supervision and review and are qualified for mass production...
CRRC Taiyuan Company encounters the largest railway activity in the southern hemisphere...
D180-16 high power and high speed diesel engine has been developed successfully...