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OPINION Legacy systems

Respect your elders Y

Dave Marples is waging a one-man campaign for legacy systems to be duly recognized for what they are – previously, they were the future

et again, I find myself sat in a presentation with very nice graphs, the presenter arguing, reasonably convincingly, that their innovation can solve all our

transport problems at a stroke. Unfortunately, on this occa- sion as on every other, in the words of the guy on the cause- way handing out directions to the lost driver; “you can’t get there from here”. In telecom, we used to have the notion of the Fork Lift

Upgrade – something sold as an upgrade that was in fact a wholesale replacement, but packaged ‘carefully’. We would install a whole new phone system alongside the old one and then, on BIS (Bring Into Service) day, flick the switch before throwing the old kit in the bin. That worked because in the constrained world of the pri-

vate telephone system you could completely install the new kit, provide user training and support the switchover as a sin- gle process. That’s not to say it was easy – on sizable installa- tions you’d have a whole team of folks on hand for BIS to deal with the things that would inevitably not going according to plan – and few project managers slept the night before BIS, I can assure you. The thing my slightly naive presenting friend has forgot-

ten is the sheer scale of our transport infrastructure, and hence the time, expense and logistical nightmare it is to effect change across it in one fell swoop – its such a challenge that, in the general case, we can’t even manage it at the single city level, and any stepwise change at the regional or national level is simply out of the question. In any transport network large enough to be useful, we

have to accommodate the legacy systems that are already there when we’re putting in new ones.

DEFINING LEGACY My trusty Longman’s Pocket English Dictionary tells me that the definition of legacy is “money or other property left in someone’s will, with a secondary definition of aftereffect”. Both these definitions strike me as rather apt for the masses of equipment that is already out there, sensing and control- ling our highways and byways day in and day out. My friend standing at the front, and many more besides,

considers legacy to be an irritating inconvenience that can, in the fullness of time, be condemned to the same scrapheap those old phones are now on. I want to argue a slightly dif- ferent viewpoint.

60 Any new equipment we deploy today will

be legacy tomorrow, so let’s start off by rec- ognizing that everything that’s out there rep- resents our investment to date – it allows our roads to operate as well as they do and gives us a foundation to build upon. Yes, you might be deploying some wonderful new direct- brain-interface traffic lights across your city, but the good old fashioned fixed timing stuff that’s in there right now is doing a perfectly good job of stopping people whacking into each other while you dig holes for the new cabinets, so don’t disrespect it. Similarly, some next generation radar-based

theatre awareness system might tell you huge amounts about the traffic in your tunnel, but it’s those traffic loops that are already there that have been doing the job until now – they might not detect objects in the carriageway the size of a small dustbin, but they’ve saved a life or two over the past 20 or so years.

INVESTING IN THE FUTURE Legacy embodies all of the investment that’s been made to date, across our entire network – and that means more than just the physical kit. There’s a sizable investment and value in all of the experience we’ve accumulated over the years – some of that is explicitly recognized in optimized designs and field-proven kit, but an equal amount is implicit and embed- ded in the people and processes that support that equipment; from the service technician who knows that when this LED is on and that meter is flickering then it’s always this board that’s faulty to the piece of Kapton tape that holds the plug into its socket because experience has taught us that it rattles loose in the field. That’s all investment that no accountant will ever recognize, but which means legacy kit works out in the field long past its ‘formal’ retirement age, and often with increasing reliability. As I write this I’m minded to compare this legacy infra-

structure to our own older generation; slightly tatty outer cases but with a wealth of knowledge and experience which goes largely unappreciated as our eye and attention is drawn to younger, flashier models. So, in my one-man campaign to recognize, celebrate and appreciate legacy (as we all edge ever closer to the human Vol 8 No 2 Europe/Rest of the World

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