1893 property and 300m is overhead the other 1km in ducting so clearly not 120 years old

I think overhead drops are going to be easier to deal with than the direct buried underground. At some point there's going to have to be a repeat of the duct laying the cable companies did 20 years ago (unless Openreach and Virgin infrastructure get forced into a separate company!).

In reply to a post by AL66:

Hmm, maybe I'm missing something but I still can't quite understand how this ready made cable is going to help except maybe for the final drop to individual properties, even then I would have thought sticking with splicing instead of connectors would be more reliable long term (as well as less attenuation).

For the bigger cables using SST surely you are going to need to splice all those fibres each time you join lengths of cable??

Why would you need to join lengths of cable?

In reply to a post by AL66:

Hmm, maybe I'm missing something but I still can't quite understand how this ready made cable is going to help except maybe for the final drop to individual properties,

Maybe you are, as there's a little more history behind the choices being made by BT for FoD2, and it has come out in dribs and drabs over the last year. The main point is that they are trying to make the final installation process - the one into the house from the fibre DP - into something quicker and cheaper, and to do this, they are re-thinking the entire method they use to deploy that section of the network.

There are 4 million DP's and 28 million properties - so this portion of the network is where the most labour-intensive work is for deploying FTTP or FoD.

In essence, the architecture remains the same from the exchange handover point, out through the aggregation nodes, and at least as far as the splitter node. Then we appear to have a couple of variation in the new architecture, but both of them are focussed on just the last couple of hundred metres into the property - a little more than just the last drop cable.

a) From Mr Saffron's blog, the old 32x splitter, a bullet with traditional splice trays, is replaced with a 4x splitter of similar construction.

Beyond this, a new secondary 8x splitter appears - as one of the Corning pole-top modules - connectorised, with pre-attached SST fibre, including the strength members.

So still splicing in the primary splitter, but a connectorised joint at the pole-top or chamber, in place of the BFT manifold.

Then there is a new kind of drop cable. This is preterminated for the secondary splitter, but can run straight into the home - so no need for a splice tray on the outside of the home (which would terminate the BFT), and no need to splice there.

b) This latest document suggests that the 32x splitter is retained, as is the fibre DP.

The pole-top module here would be a plain distribution terminal, with multiple connectors, rather than a splitter. The SST tail from this would feed back to the DP, and be spliced there.

The same drop cable would be used.

even then I would have thought sticking with splicing instead of connectors would be more reliable long term (as well as less attenuation).

One of the first BT presentations on NGA2 made the point that they had sufficient attenuation to play with, and were investigating whether stepping back on the all-spliced solution was viable, and gave them enough gains in deployment time.

In this case, time very much equals money - and therefore viability.

For the bigger cables using SST surely you are going to need to splice all those fibres each time you join lengths of cable?? It there's an issue with the BFT maybe fitting that with strength members too would enable more forceful methods to get it through the ducts?

The SST drop cables will only likely cover the final 200m max - remember that, on average, homes are now only 400m from the cabinet.

The other cables from exchange to splitter/DP will remain as-is, spliced as before and they were never BFT tubes anyway. They were up to 288 fibre cables in the spine, and perhaps 48- or 96-fibre cables from aggregation node to the splitters and DP's. BFT was only ever used for the part after the DP.

As you can see from this recent presentation, the size of 12-tube BFT is huge compared to SST, so a strengthened one would be larger still - you'd still have the problems in congested ducts, you still wouldn't have the gains from the pre-terminated connectors, and you'd still need a splice tray outside the home (which is, apparently, aesthetically challenging).

Pre 1990 estates - was it not common practice for all cables (lead ins and under pavements, etc) back to PCP to be direct buried? My own house built early '60's, everything is direct buried even though there are small 'GPO' concrete covers in the pavement, each share between two houses - asked an engineer when he came for a fault, no duct anywhere.

I think it was common for certain times, but certainly not all. Mid sixties to mid-seventies?

Analysys Mason did a report on the poles and ducts of the access network back in 2010; I think to establish data about how much full/empty existing ducts were, how full poles were etc - probably to feed into the PIA work.

It can be found here:
http://stakeholders.ofcom.org.uk/binaries/consultati...

That report suggests the problem of "direct-buried" cables is mainly within the drop cable to homes, and not between chambers. See Figure 3.16 or 6.1.

One thing they reported was that 24% of DP's were underground, 47% overhead, 22% internal (eg inside an MDU), 7% external (eg outside wall of an MDU or terraced block).

They figured that underground drop infrastructure figured more post-1968, and that Openreach network plans didn't distinguish whether cables were ducted or direct-buried.

However, using cable sizes (the direct-buried ones would be armoured, so thicker), they figure that the proportion of ducted last-drop cables could be between 41% and 81%. They don't say that this conclusion only applies to the 24% of DP's that are underground, but it seems a fair assumption.

By their analysis, it is safe to say that 20% of underground last-drop cables are big enough to be armoured - so direct-buried likely accounts for 20% of 24% of premises - or around 5% of the UK.