If it were easy, everyone would do it

In the early 1970s, British Rail was modernising and electrifying the West Coast Main Line from Crewe to Carlisle. Just three Power Signal Boxes at Warrington, Preston and Carlisle would take over the work of a large number of mechanical signal boxes. My firm had had some success in designing selective call systems for use over Private Mobile Radio so, when we were invited to tender for the design and supply of selective call telephone systems for the West Coast Main Line, we were keen to be involved. As far as we could tell, the opposition was still using mechanically tuned resonant reed relays. This was a well-established and reliable approach, but with a number of technical restrictions and relatively expensive.

We came up with an approach using a small number of voice frequencies transmitted as a sequence of tones which were electronically generated and detected. Provided that we could reduce power consumption sufficiently, the technique offered the possibility of a completely line-powered system with significant economies. Low power digital integrated circuits were just starting to appear, using Complementary Metal Oxide Silicon (CMOS) technology, and these devices seemed to offer exactly what we required. Motorola, one of the early manufacturers, were keen to expand their sales and so we tendered based on this approach and were delighted to be awarded the contract.

Detailed system design went ahead and the prototype equipment was built using the Motorola devices. Everything worked well so purchase orders for the production quantities were placed. Only then did problems appear. Motorola would not confirm delivery in line with their quotation and the truth only came out during a long telephone call with Phoenix, Arizona. Deliveries of the production quantities would be delayed by many months - an unacceptable position. We had been cautious enough to ensure that there was a second source for the integrated circuits at R.C.A., but not cautious enough to discover that only superior, military versions of the integrated circuits could be shipped in any reasonable timescale. The military versions were about ten times the cost of the industrial versions which we required and the effect on the project would have been disastrous. Not for the last time in my career, I felt utterly dejected.

Not knowing when to give up, we continued to search for an alternative. The ability to line power the equipment had been a major factor in the selection of our design but this was the hardest feature to reproduce if the CMOS devices were denied us. Eventually, we produced another prototype system which used exactly the same signalling system as the original design but where the integrated circuits were replaced by low-power silicon transistor stages. Quite a lot of the design effort had to be repeated but, at the end of the day, we were able to meet our commitments to British Rail and survive as a business. Subsequently, we received substantial repeat business from British Rail.

So, is there a moral to this tale? I'm sure there are lots, but I'll leave you to decide what they should be. It convinced me of the truth of the saying "If it were easy, everyone would do it".