Cables under Pavement

[Michael]

Hello all,

 

If you have school A and school B who are say 50 metres apart max and I want to lay fibre between the two, what are the requirements in terms of laying fibre from one to the other going under the public roads/pavements? If it were all on-site of course, this wouldn't be a problem!

 

I can get the fibre and I could get a contractor (in theory), and presumably you need a license to dig up the road/pavement/grass, but what about the long-term costs? Do you pay the council? How does it work?

[HarryMonkey]

You would need to contact your local highways department and get way leave. There's all manner of hoops to jump through, even down to the likes of organising traffic lights for the road works etc This is not a job for the faint hearted methinks.

[sparkeh]

There is a bit about permits to dig up the road here: https://www.gov.uk/government/publications/street-works-faq

It seems the procedure varies from LA to LA so best to contact your own LA to see how they operate.

[PotNoodleTech]

Have you got line of site between buildings on both sites? I would dig up the public highway as a very last resort.

[ericscher]

Hello all,

 

If you have school A and school B who are say 50 metres apart max and I want to lay fibre between the two, what are the requirements in terms of laying fibre from one to the other going under the public roads/pavements?

 

 

It's actually possible to drill under a roadbed horizontally. The expense is governed mainly by the width of the road. Your contractor can give you the details. You will also want to enclose in direct-bury metallic conduit, because otherwise rodents will cut your link on a regular basis.

 

Also, if there overhead telephone/electrical wires suspended on telephone poles (ubiquitous here in the USA) you can usually manage to get permission to use the poles to cross the road.

And of course, if the buildings in question are of sufficient height and local zoning allows, it may be viable to run an overhead wire from building to building. There is special cable for that which contains it's own tool-steel suspension wire.

 

 

Having said all that, AButters may have made the best suggestion, unspoken though it is. At 50m your 60% 1st Fresnel zone for 2.4GHz is only about 1m. Heck, your 100% zone is only about 1.5m.

A wireless link may be your best overall option, assuming your weather/atmospheric conditions are amenable to that.

[ICTDirect_Dave]

Could you not get the cables pulled through the usual channels? Seems a bit much to have to dig up the road if you could just get it dragged through whatever utility cable channels are currently there.

[Blue_Cookeh]

Have you looked at a wireless solution? Using some gear from Ubiquiti you could actually get better performance than fibre assuming you have line of site.

 

I think you'd be looking at their AirMax range for this sort of thing. UniFi wouldn't be enough, but I think airFiber would be overkill.

 

airMAX | Ubiquiti Networks, Inc.

Edited March 20, 2014 by Blue_Cookeh

[JPElectron]

airFiber | Ubiquiti Networks, Inc. might be more appropriate, depending on bandwidth, and if wireless is the way you need to go.

 

A hard line would be best, a directional boring machine, see: https://www.google.com/search?q=directional+boring+machine&tbm=isch can easily run a fiber conduit without breaking up the road. Your cable contractor would be the best one to tell you if this is appropriate, and pull any necessary permits.

Edited March 20, 2014 by JPElectron

[Michael]

Thanks all - I knew these were the kind of answers I'd get, but it's something worth exploring. Realistically despite wires in the ground being the best option, it'll cost considerably more than any outdoor wireless system, which leads me onto the next question -

 

What kit have you used or are using with or without a line of sight and with what sort of transfer rates?

 

Of course the other alternative is a point to Point wired solution which can be cost effective too. A 100Mbps PTP is cheaper than a 100Mbps internet connection for example.

[Michael]

Thanks all - I knew these were the kind of answers I'd get, but it's something worth exploring. Realistically despite my own wires in the ground being the best option, it'll cost considerably more than any outdoor wireless system, which leads me onto the next question -

 

What kit have you used or are using with or without a line of sight and with what sort of transfer rates?

 

Of course the other alternative is a point to Point wired solution which can be cost effective too. A 100Mbps PTP is cheaper than a 100Mbps internet connection for example.

[Jamman960]

We needed to link our two sites(220m with houses in between) a few years back and looked at all of the options including fiber via the sewer, ptp leased lines and fiber via the railway line running behind both sites, in the end we went with a 1gbit FSO link with RF backup, it cost us just over 10k plus 1.8k per year maintenance which still works out cheaper than the other options that meant paying line rental etc.

 

Fiber via the railway looked to be the best option until we started looking into the costs, 1.5kish for a survey followed by paying for them to close the line plus paying their chosen contractors to do the actual work. The worst bit was having to pay for closure again if the fiber were ever to be vandalised which could happen at any time - it was a potential endless money pit so we left the idea well alone. From what I understand the wayleave fee's would have been tiny though.

[snagrat]

Look at the Cambium PMP450. That is good for backhaul links. Can provide up to 1GB throughout. Also works in non Line of Sight situations.

 

You may need to consider licensed band link so the houses between you do not interfere with you.

 

The solution won't be cheap, but wireless is probably the cheaper solution.

[Graham-Millgate]

I have done jobs in situations similar to this at few schools such as one where we dug up a road to run some fibre and another where we connected 2 buildings by fibre using a catenary wire but both were on the schools property so we never had the headache of dealing with the LA. The catenary option worked out cheaper on private property based on a 75m run against wireless though so maybe worth a call to the council to find out if running catenary wire would be ok?

[Chris_]

We have a couple of fibre links across public roads, one is on a catenary. The other went underground and required digging up the road. It was done before my time so I'm not sure how much it cost and what procedures need to be followed. Underground requires much less ongoing maintenance work than overhead on catenary wires

[cpjitservices]

Here... you'd pay £250 for a Section 50... This gives you the permission to go digging,, you then need suitable ducting and possibly sub-duct to go in the trench.

 

Any contractor would do the job as long as you have it in place for permissions and so on.