It’s an interesting subject and when I’ve spoken with other engineers in the past we have had differing opinions / results. However, I think you need to consider all of the costs and our simple calculations showed a payback period in energy costs alone of around 8 years. So on the basis of a 12 year lifetime you are getting an extra 4 years of energy savings, as well as bulk change (once a year maybe?) and occasional lamp faults. And you help to meet the Government target in respect of energy use/carbon footprint so the benefits to the Authority are greater than just the immediate signal section benefits. Having said all of that, we no longer carry out retrofit of aspects due to all of the problems we have had and only fit LED aspects to new and refurbished sites.
In respect of replacement, for the past 11 years our contract has stipulated that the maintenance contractor meets the costs of replacement with the Authority meeting the TM costs. On tall poles this usually means mobile works using an IPV and MEWP so we wait until there are several failures before tackling them all in one sunday morning operation.
Just wondering if anyone has conducted any calculations to establish the savings (or otherwise) that can be generated over a lifetime of operating LED signal heads vs halogens, and if they’d be prepare to share them with me? A client has asked if it is really cost effective to change all the heads to LEDs when they cost so much and when (as he is finding out now) they will have to be replaced in 12-15 years time due to excessive failures. We can get 20 years out of a halogen signal head (sometimes more), but of course more lamp failures can be expected with halogen lamps over the life cycle.
I would also appreciate any information on how authorities manage their LED replacements when they get to a certain age and become ‘obsolete’. Do most authorities bite the bullet and pay for them to be replaced? Or do they insist that the maintenance contractor continues to maintain them, replacing aspects as and when required and accepting that finding replacement aspects may get more and more difficult?