Blowing a second optical cable into an existing pipe

In many countries of the world, telecommunications operators are increasingly faced with the problem of lack of network capacity (lack of optical fibers). How to solve it quickly and inexpensively: build new communication lines or use wavelength division multiplexing? Since most of the optical highways on the planet are built by pneumatic laying of one cable in a protective pipe, the best solution is to install a second one into it.

Advantages

The technology of blowing a second cable into the existing pipe allows the customer to save in the following items of capital costs.

Design work

When blowing in the second cable, there is no need for new design (surveys, approvals, land allocation, expertise, etc.); the design and as-built documentation of the communication line in which the second cable will be blown out is used. In addition, only the need for compensation to land users may arise, but it is relatively small compared to compensation during the initial construction.

Materials (edit)

When blowing in the second cable, there is no need to purchase a pipe, signal tape, signposts, etc.; the existing materials of the communication line in which the second cable will be blown are used. In addition, you just need to buy a cable and restoration couplings for the pipe, as well as, in some cases, optical couplings, TKP cameras and branching devices.

Construction works

When blowing out the second cable, there is no need for complex earthworks for laying a pipe and signal tape, installing signposts, etc.; the existing materials of the communication line in which the second cable will be blown are used. Only the development of small pits for blowing the cable and the installation of optical couplings, as well as, in some cases, the installation of TKP chambers and branching devices is carried out. The production of a team of blowers is reduced by about three times.

Example

To demonstrate economic efficiency using an example, we will first study the building codes for this type of work.

According to the regulatory literature (see clause 1 of the list at the end of the article), when blowing cables into pipes, they are guided by the following provisions:

Illustration No. 15 - the range of blowing the first cable with a diameter of 10 mm (typical for modern products) into a pipe with a friction coefficient of 0.1 (typical for modern products) is 1.5 km;paragraph 14.42 - the distance of blowing the second cable into the pipe is 50% of the blowing distance of the first cable.

This confirms that blowing a second cable into an existing pipe is easily feasible and only requires more frequent excavation of pits.

Consider the capital costs for two options for the construction of fiber-optic communication lines. Let's assume that the length of the route is 1000 km, there are no intersections and transitions on the route. We will consider only the main types of materials and work (their share in the cost of any construction is 95%).

Comparison of the tables below shows that blowing the second cable into the existing pipe, in comparison with the construction of a new communication line, has a total saving of about 50%, despite at least a threefold decrease in the output of the assembly team.

Option 1 - Construction of FOCL with pipe laying and cable blowing.

Option 2 - Blowing out the second cable with the installation of new sleeves and chambers CODE.