On Tragedy, Train and Technology

 As a member of a Railway family,  as an ex Railwayman, and as a mechanical engineer, I am much pained by the serious loss of life in the train accident which occurred in the Balasore District of Odisha.

Train accidents with passenger casualties seemed to have become part of the history. Mass casualty accidents seemed so 'last millenium' phenomenon - the days of Gaisal or Purushottam Express accidents.

One silent revolution that had happened in the last few years was the increasing use of LHB coaches, with CBCs, in place of old ICF coaches with screw couplers. Even ICF coaches have been increasingly fitted with CBCs

To elaborate further, old timers may recall the two big plate like structures on two big cylinders, fitted on both ends of the coaches. They were the buffers, to prevent impact between the two coaches during shunting, or braking. They were an adaptation of the spring dashpot shock absorber. While effective as a buffer "normally" (when the train is on the track), it offered no buffing protection when the buffers on either side did not align (in case of an accident).

Old timers may also recall the thin screw and hook sort of structure (situated near the more obvious brake pressure hose) in between the two buffers. It appears thin, and it connected the two coaches by sliding a nut sort of appendage over the screw of the other side, thus making a tension only rigidity - this means that the bond was rigid only on pulling. Otherwise, a coach was free to rotate about the other coach in any which way. It was as if two bricks have been tied with a piece of string.

In its place, the Central Buffer Coupler (CBC) combines the Buffing and Coupling components in one device. The two ends are quite rigid structural elements which are connected to the coach frame, and they connect the two coaches in a way a hinge does. The coaches are allowed to rotate only along a vertical axis. (The way one coach is 'turned' with respect to another while the train is on a curve). Plus, since the 'buffers' are positively connected, they are available for buffing protection even in "not on rails" cases.

Now we need to look into a few mechanical phenomenon which cause fatality in rail accidents -

1. The coaches of the same train run through one another, in a phenomenon known as 'telescoping' (it looks like the two tubes of a telescope sliding into each other). Obviously a coach sliding into another can cause severe trauma to any occupant of the other coach.

2. Coaches under impact climbing on each other, and then falling from a great height. This causes trauma by fall.

3. Coaches derail onto another track, and get run over by another train. Side walls of the coaches are not designed for impact and the potential for trauma is extreme. 

4. Occupants flying out of their seats / berths on impact, and colliding with fixtures.

The mechanism number one was a very common occurrence in the past, till the railways adopted the "anti telescopic design", in the ICF coaches. It was mainly done by differential strengthening of the coach body. The doorways are the weakest, and the toilets are the second weakest. The main body housing the passengers is the strongest. In case of impact, the weaker parts get crushed first, and absorb most of the energy, thus saving the main body from the brunt of the kinetic energy, as well as forming obstruction for body of one coach entering the other. That is another reason to be noted for avoiding footboard travel (or hogging the toilet for too long, for that matter!) 

The LHB coaches with CBCs took care of the second mechanism. While screw couplers are weak and limp, the CBCs are rigid. Thus screw couplers break too easily, allowing the coach to fly anyway it prefers, and even if it does not break, it can allow the coach to turn upside down. The CBC remains rigid, and even on derailment the whole train sort of "stands straight". At most it can get wavy like a snake. But coaches don't turn turtle, or climb on each other and fall. In the past decade, a Rajdhani Express had derailed at full speed, and there was not a single life lost.In fact, as a person knowing about this technology, one was rather assured about the safety of rail travel (which it still is compared to road travel). Even in the photographs of the current accident, one can see that the parts of the train which did not collide with the other train are situated in a rather 'disciplined' manner. However, much of the loss of life is due to the third mechanism.

The third mechanism cannot be secured against from any improvement in the coach design. Although CBCs restrict how far a coach can fly on derailment, still, parallel tracks are two close to avoid spillage of coaches from one track on the other. Locating parallel tracks far enough is not feasible - would be very prohibitive in cost and time cosuming.

One method which may be used, is to avoid high speed crossing / precedence automatically. The Anti Collision System is already functioning. It may be used to automatically reduce the speed of both trains to a limit where the loco pilot can stop the train by emergency brakes, if he spots obstruction by coaches of another train. It may have its costs in speed reduction, but, barring a "great wall" or "great net" between parallel tracks, no other thought comes to mind to secure against this mechanism of life loss. This may sound like an outlandish idea in rail operations, but it is a very common precaution we take everyday on roads, going slow when crossing another vehicle.

The fourth mechanism is the most unfortunate, as it is inherent independently in all the other mechanisms, and also because the simple intervention of better securing the passengers and luggage can minimize it to almost zero. Road vehicles have had seat belts mandatory for long. However, we have still not started using them, even optionally, on trains. The provision may not be that difficult - it can be incorporated in the berth itself, without disturbing the coach interior per se. A retractable net below the lower berth can be used to keep the luggage mechanically secure. 

To summarize, two low cost interventions that may be done quickly are -

1. Incorporating mandatory slow speed crossing / precedence in the General and Subsidiary Rules of Railway operations, and augmenting the ACD to actuate this automatically.

2. Provision of seat belts and retractable safety luggage nets in all high speed coaching stock.

The railways have steadily been using technology to better secure passenger safety. Anti-telescopic design, CBCs, Anti Collision Devices are some major interventions in the direction. However, misfortune is a sneaky enemy, and constant vigilance and technological improvement is the only way forward.