Computer and electronic equipment in Railway Signaling
Somnath Banerjee
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The use of computers and other electronic equipment in Railway signaling applications has fallen far short of developments in other similar fields of control. The main reason behind this is the apprehension of the signal engineers about the required levels of safety which can be achieved by electronics safety at reasonable costs. The logic that the introduction of electronics in Railway signaling is due to failure to satisfy the safety and reliability standards of a Railway system is not a truth in proper sense and the main reason appears to be the costs for a sufficiently safe and reliable system for Railway signaling needs has not been available in the earlier stages of development of electronic and computers. That this is the truth can be understood from the fact that electronics has been used in many areas where safety requirements are far more stringent than Railway Signaling. Similarly electronics and computers have also been used in systems where reliability requirements are far more stringent than the Railway signaling. Thus where safety is concerned the aviation industry is far ahead of Railway signaling in introduction of electronics. Electronics is even extensively used in space missions. On the other side where reliability is of paramount importance as in banking industry , Reservation systems in airline ticketing or Railway ticketing the use of computers is very widespread. Similarly where moderate safety and reliability requirement is required as in the process control systems the use of computers and electronics is also quite widespread.
The main reason why therefore the introduction of computers and electronics has lagged behind in Railway signaling is the combination of two factors
a) Non availability of electronic systems which are cost
effective even small scale
b) Systems which can substantially change the operating costs of
a Railway operation while keeping in view the level of traffic
which may be already saturated due to other reasons. There are
many systems in the world where the Railway management is highly
inefficient to attract additional market due to inefficient
marketing and service .On such Railways the increased efficiency
that a electronic signaling system can offer cannot be used by
the Railway concerned and hence the investment on electronic
signaling is not considered economic.
Now however with the continuous downtrend in the cost of electronic systems the use of electronics in Railway signaling can improve and its time to address certain key issues in this area. Developments are needed in the following areas
a) development of electronics which can operate in extremely harsh electromagnetic interference regions due to the widespread use of electric traction ./ The use of electronic traction creates high level of electromagnetic interference and this must be protected against. An efficient earthing system is an important element in this direction . A design of a efficient earthling system is detailed here. In addition the electronic equipment design has to be done keeping this in view.
b) For achieving safety with reliability these options are in vogue . Out of these options the option with redundancy offers the best solution in view of higher availability.