FTTH Project OSP Notes : Small Trenching Specifications

Trenching views

Small trenching in FTTH Project OSP

Specifications of small trenching used for civil OSP in FTTH project. Why Small Trenching used in FTTH Project and what is the use of this, we will discuss on this topic.Why called small trenching and what is the specification, I will explain each and every thing in this post. We are already familiar about the trenching done in telecom project called OSP project for FTTH/Junction/Long-distance networks. Here no need to discuss about the open trench & trench-less details. I would like to focus only on small trenching and their specification used in FTTH project.

You are well known about the feeder network known as metro network and distribution network. In other words, we can say that this is a backbone of the FTTH project. Now I would like to draw your attention towards the "what is small trenching specification of feeder/Metro network in FTTH Project OSP?. 

SMALL TRENCHING FOR METRO (FEEDER) AND DISTRIBUTION

Small Trenching, is to be used in networks between exchanges and from exchanges to the access sites/cabinets. It is also used in distribution networks from fiber distribution terminal (FDT) to a handhole and between handholes.

Trenching size may vary from country to country. All telecom operators use the trenching parameters according to country climate & suitability. Small trenching widely used in gulf countries and European countries, USA,France,etc. not used in Pakistan, India, Shrilanka, Bangladesh etc.

Trenching size, in this case, must be 200mm width and 600mm depth from ground level. This trenching can maximum accommodate 20 x 32/26mm ducts and 25 x 20/16mm ducts. 

Feeder Routes (Exchange To FDT)
Trench: 200 mm width, 600 depth from Asphalt / 500 mm from GL.
Ducts: - For Streets wider than 30 m: 20x32 mm dia. + 16x20 mm dia.

             - For Streets less than 30 m: 16x32 mm dia. + 16x20 mm dia.
Colors: Black ; Orange; and Orange with Black Stripes B) Depend upon the company specifications.

small trenching and duct position details

Small Trenching for Feeder and Distribution

SMALL TRENCHING FOR DROP

Drop trenching is to be used to install drop ducts between MH/HH and customers. The dimensions of this trenching is 130mm width and 450mm depth. This trenching can

accommodate from 2 drop ducts to a single customer up to 24 (20mm) drop ducts to serve 12 customers.Check below details-

Distribution Routes (FAT To Client):-
Trench: 130 mm width, 500 depth from Asphalt / 400 mm from
GL.Ducts: 25x20 mm dia.&
Drops To Houses:-
Trench: 130 mm width, 450-500 depth from Asphalt / 400 mm from GL.
Ducts: 2x20 mm dia.

MICRO TRENCHING FOR FEEDER AND DISTRIBUTION (NO SHARING)

Trenching, is to be used in networks between exchanges and from exchanges to the access sites/cabinets. It is also used in distribution network from fiber distribution terminal (FDT) to a handhole and between handholes.

Trenching size, in this case, must be 100mm width and 500mm depth from ground level. Colors of the ducts must follow the color codes specification of the telecom operator.

MICRO TRENCHING FOR FEEDER AND DISTRIBUTION (WITH SHARING)

In case the civil network is shared with other operators a 4-way 10/6mm bundles must be
installed to customer’s buildings.

feeder details

Feeder\Distribution Trench

MICRO TRENCHING FOR FIBER DROP DUCTS (NO SHARING)

Trenching, is to be used from handhole to customer. Trenching size, in this case, must be 100mm width and 350mm deep from ground level.The number of drop duct groups that can be placed within the same trench must not exceed 12 groups, one group for each building/lot.It be more clear from below mentioned figure.

Drop trench

Drop Trench (No Sharing)

MICRO TRENCHING FOR FIBER DROP DUCTS (WITH SHARING)

Trenching size, in this case, must be 100mm width and 400mm deep from ground level. The

number of drop duct groups that can be placed within the same trench must not exceed 12

groups, one group for each building/lot.see the below image-

drop duct details

Drop Ducts Trench

Easy overview of Trench Dimensions Duct Size In FTTH Network-

Feeder Routes (Exchange To FDT):-
Trench: 200 mm width, 600 depth from Asphalt / 500 mm from GL.
Ducts: - For Streets wider than 30 m: 20x32 mm dia. + 16x20 mm dia.
- For Streets less than 30 m: 16x32 mm dia. + 16x20 mm dia.
Colors: Black ; Orange; and Orange with Black Stripes B)
Distribution Routes (FDT To FAT):-
Trench: 200 mm width, 600 depth from Asphalt / 500 mm from GL.
Ducts: 12x32 mm dia. + 25x20 mm dia.
Colors: Black (6); Orange (3); and Orange with Black Stripes
Distribution Routes (FAT To Client):-
Trench: 130 mm width, 500 depth from Asphalt / 400 mm from
GL.Ducts: 25x20 mm dia.&
Drops To Houses:-
Trench: 130 mm width, 500 depth from Asphalt / 400 mm from GL.
Ducts: 2x20 mm dia.
Length of duct Not more than 300 meters from FAT
Drops To Houses:-
Blown Fiber
Trench: 130 mm width, 500 depth from Asphalt / 400 mm from GL.
Ducts: 2x2X14 mm dia. Or 50 mm duct with 4x14 mm micro ducts.

Summary

This small trenching specifications has been followed in FTTH project OSP. Its not a standard of all over the world but in major part of the world followed the same specification for small trenching for the FTTH project OSP. I hope this post would have liked and will also assist you to complete the FTTH project in better way.