Just a little advice if you don't mind. Our authorities CCTV department are looking into providing there own own private fibre network for there cameras around the town in order to get rid of the huge rental costs we all experience. They have asked me for a plan of my traffic signal duct network in order to utilise this where appropriate and to save themselves costs in ducting.
My question is are there a reason why i should'nt let them share the network and what have other authorities done regarding this.
It could actually be quite useful for me as i could utilise the dark fibre for my traffic signal junctions.
In stoke we have completed the same project of installing a private fibre network for traffic signals and CCTV only it was completed by us rather than CCTV. We have also used the signal ducting where possible to reduce the amount of overall ducting needed for the initial install and so reduced the costs considerably.
The only real issue you will face with this is contractors working in access chambers with fibre and traffic signal cable where for example during a recabling of the signals the contractor damages the fibre or vice versa but in our experience as long as you make the contractor aware beforehand this is not normally a problem. In any case you could insist on your CCTV department that cables in your access chambers are clearly marked with tags or sub-ducted.
Your potential for revenue savings is quite considerable, especially if it passes through SCOOT sites and if they are wanting to use your ducting its a good bargaining chip to get them to supply and install the kit to link your signals at the same time.
Sharing of signal ducts is not uncommon and as Andrew indicates can produce potential benefits.I would suggest however that you ensure that the capacity of the duct network is not compromised by any additions, and that the chambers themselves do not become a 'birdsnest' making it difficult for future maintainance of the signal cable network. It is quite normal for the duct network capacity to be calculated during the signal design stage to include some redundancy for future additions, and so as indicated above, to compromise it would not be beneficial overall.
We share our private wire ducting in Derby, but generally only for ITS (so that includes CCTV). We were approached with a plan to install a kilostream link between buildings for general data transfer and although we said yes in principal nothing ever came of it. We insist on tags in every chamber when the second service goes in.
It's difficult to know on what grounds you could refuse since it's an asset belonging to the Authority even if it was originally envisaged for signal use.