Building the Network

Superfast Northamptonshire is a large scale civil engineering infrastructure project which is helping to extend new fibre based broadband technology across the county.  It involves detailed planning and physical works to roll out hundreds of miles of fibre network and to install hundreds of new structures (such as green roadside cabinets and manifolds) and electronic equipment which together form a network which enables superfast broadband services to be provided.

There are several key stages for the deployment of the broadband network, depending on the technology solution used to serve a particular locality. The fibre based technology that is being delivered for the project by BT includes:

  • Fibre to Cabinet (FTTC) 
  • Fibre to Premise (FTTP)

Other technologies are also used by the industry including fixed wireless and satellite broadband. 

FTTC FTTP Diagram.jpg 


These are the same technologies used by BT for its commercial deployment and similarly are used by a number of other telecoms providers.

Planning and survey work informs detailed network design and the location of equipment essential to that network.  It involves going out on site to survey all the underground ducts serving homes and businesses in the planned coverage area. Surveyors will also check whether there is access to a power source.  This is important as new cabinets supporting fibre need power whilst existing cabinets supporting traditional copper networks do not.

A plan is then drawn up for exactly where the fibre, new ducts, street cabinets and additional underground and over ground equipment will go. The planners and surveyors will work with the Highways Authority and local planning authorities to ensure local considerations are taken into account as far as possible and that the best location for the installation of new cabinets and equipment can be found.

Cabinets.jpg

There are many considerations in this respect including being sensitive to areas of conservation, trying to avoid obstructing footways, avoiding trees (and therefore tree roots which may cause damage), avoiding existing buried utilities like gas and water pipes, ensuring the line of sight for highway users is not obstructed, and considering land ownership and any wayleave permissions, amongst others.  Ideally, new cabinets supporting fibre need to be located as close to an existing copper cabinet as possible to maximise performance.

The informatiCATon gained from the planning and survey work will shape the actual network build programme.  This may be different from the shape of plans as initially modelled prior to survey. This is because unforeseen issues may be identified at the survey stage which cause plans or parts of plans to be delayed or changed.  This could include, for example, the discovery of blocked or collapsed ducts under the ground or ducts which are full to capacity, or there may be no accessible power supply in the area.  An example from elsewhere in the UK involved delays because a badger set lay in the path of the fibre build and the network needed to be re-routed!  Plans or parts of plans may also be delayed or changed if an issue results in a significant cost increase whilst solutions which deliver better value for money are sought.  These are all things which can't be known until engineers get out on site to complete their surveys. 

Incidents can happen throughout the network build process so there is always a risk that plans may be subject to change as a result of unforeseen issues.  This is why information on expected timescales for plans to come forward are indicative only.

Fibre To The Cabinet (FTTC) is the main technology that is being delivered by the County Council's two contracts with BT. This involves laying fibre from the exchange to a new cabinet structure (green roadside box) known as a DSLAM which essentially brings the exchange closer to the premises being served.  The DSLAM is connected to the existing copper cabinet located close by and services are provided over the copper network from the cabinet to the home or business.  FTTC can provide for speeds up to 80Mbps for those located closest to their serving cabinet.

There are 5 key stages involved in the deployment of FTTC.  These are described below starting from the bottom upwards:


FTTC solutions generally enable most premises served by the cabinet to take up superfast or faster fibre broadband services.  However, because the last leg of the service is delivered over the existing copper network, the access line speed available will reduce the further a premise is away from its serving cabinet.  This means that some premises within a fibre enabled cabinet area may not see a beneficial speed uplift from that particular solution.  These premises will remain part of the Superfast Northamptonshire project and solutions will continue to be sought through future stages of the project.

PICT2395444.JPG

 

In some areas an FTTC solution isn't appropriate.  An alternative solution is Fibre To The Premise (FTTP) which involves extending the fibre network all the way from the exchange to the home or business – there is no reliance on the existing copper network.  FTTP is more costly to deploy than FTTC which is why it is not the first choice solution for the project but it also supports faster services including speeds of up to 330Mbps. Other FTTP providers like Gigaclear offer gigabit services over a similar FTTP network.  This technology is more complex to build and therefore normally takes longer to deploy than FTTC.  The key stages involved in FTTP build are described below:


Some premises are served by Exchange Only (EO) lines; these are copper network connections that run directly from the telephone exchange to a home or business; this means they are not served by green roadside cabinet. These lines are generally either very close to the telephone exchange or very remote from it. EO lines can be fibre enabled in a number of different ways.  Solutions include:

  • building a new copper cabinet close to the exchange and re-arranging the EO lines from the exchange to the new cabinet.  A new fibre cabinet can then be installed to provide a Fibre to the Cabinet (FTTC) solution.  Sometimes an 'all in one' cabinet is installed instead – this is a single cabinet which does the same job as the copper and fibre cabinets together.

  • sometimes a Fibre to the Premise solution may be deployed instead.  This means new fibre cabling is run all the way from the exchange direct to the home or business without the need for a cabinet.  The existing copper network would be unaffected.

Re-arranging the copper network to install a new fibre cabinet is complicated and will normally take a longer time to deploy than a standard FTTC solution and is more costly.

You can find out more about where the network is being built on the 'Roll Out Schedule' page.  This lists all of the cabinets that have been installed by the Superfast Northamptonshire project and where fibre services are now available.  It also lists places where services will be 'Coming Soon'. The fibre network spine being built connects these cabinets back to the telephone exchange.  This involves laying fibre in ducts normally under the ground and in some cases fibre can be blown through existing ducting. 

Permission is required from the Highways Authority to undertake necessary works on the counties roads and in the event of temporary road closures or traffic management requirements to enable civil works to be undertaken by engineers safely.  Where the network needs to be built across private land, a wayleave needs to be agreed with the landowner which grants permission to do so. 

It is worth noting that not all premises in a locality may get access to superfast broadband in the same phase of the project.  This is because, despite proximity of premises, they may not all be served necessarily from the same network infrastructure and therefore could be subject to different solutions or timings.


The Big Build

To understand more about how the network is built, you can view BT's Big Build video here.

 


For more information about the Building the Network, please visit our

© 2015 Superfast Northamptonshire