How far can fibre optic cable be blown through an underground duct?

The case study states that the pneumatic systems can blow fibre optic cable through an underground duct for distances of up to 1 km.

Why was a 3.5-ton GVW utility vehicle developed?

Existing 7.5- and 10-ton GVW cabling vehicles were suitable for larger roads but were too large for some B roads and minor routes. The 3.5-ton vehicle provided a smaller platform capable of working in more confined spaces.

What does the hydraulic system power?

The hydraulic system powers equipment including the winch used to remove existing cable, the rodding machine used to clear underground ducts and various hydraulic hand tools.

Which compressor systems were used in earlier cabling vehicles?

The original Medium Cabling Unit and Light Cabling Unit used Tamrotor E12 and Tempest3 compressors, together with Webster power take-offs.

Fibre Optic Cable Installation Vehicle

Q: How does the winch load monitoring system work?

A load-cell-based measuring device digitally displays pulling force and sends a signal to stop the winch when maximum pull is reached. The monitoring unit is solar powered.

Overview

Installing and replacing fibre optic cable requires more than compressed air. Utility vehicles may need to power winches, clear underground ducts, operate hydraulic tools, remove water from manholes and blow fibre cable over long distances.British Telecom worked with Gardner Denver to develop vehicle-based systems that combine pneumatic, hydraulic and electrical power for cable installation and maintenance. The collaboration included adapting driveline technology to a 3.5-ton GVW van, creating a smaller vehicle capable of operating on minor roads and in confined spaces while retaining fibre-blowing, hydraulic and electrical capabilities.

Challenge: Fibre Installation on Smaller Roads

Gardner Denver had supplied British Telecom for more than 25 years, supporting the repair, replacement and installation of telephone and fibre optic cabling. Existing Medium Cabling Units and Light Cabling Units used Gardner Denver compressors and Webster power take-offs to support cable operations. Larger 7.5- and 10-ton GVW vehicles had been used for work on motorways, dual carriageways and A roads. Their size, however, made them less suitable for B roads, minor routes and more confined operating environments. The challenge was to bring the essential functionality of the larger cabling vehicles into a smaller, more versatile platform.At the same time, British Telecom had identified another operational problem: ropes breaking during winching because operators did not have an indication of rope tension before maximum strain was reached.

Solution: Integrated Pneumatic, Hydraulic and Electric Power

To address the vehicle-size requirement, Gardner Denver UK incorporated its Highway & Utility driveline system into the existing technology and converted an existing 3.5-ton GVW van. The resulting compact utility vehicle can provide the pneumatic power required for fibre blowing while also producing hydraulic and electrical power.

Pneumatic power for fibre installation

Once an underground duct has been cleared, compressed air is used to blow fibre optic cable through the duct for distances of up to 1 km. Pneumatic power can also operate a duct motor capable of pulling cable or feed wire through the duct.

Hydraulic power for cable and duct work

The hydraulic system supplies power to a winch used to pull old cable from underground ducts. A rodding machine can then clear the duct in preparation for new cable.Hydraulic power can also operate various hand tools required by field teams.

Electrical power for field operations

An onboard alternator provides electrical power for equipment including:

Fusion welding equipment
Water pumps for clearing flooded manholes
Emergency work lights
Other onboard electrical equipment

Together, these systems provide a multi-function vehicle platform for fibre installation and utility operations.

Winch Safety and Load Monitoring

During discussions about the project, British Telecom identified issues with ropes breaking during winching operations because operators lacked an indication of the tension being applied.Gardner Denver Engineering and Electronics developed a load-cell-based measuring device to address the problem. The system digitally displays pulling force and sends a signal to stop the winch when maximum pull is reached.The monitoring unit is solar powered. Following development of the solution, British Telecom ordered units to accompany its cabling vehicles. Further discussions about the reliability of existing winches also led to an additional order for new winches.

FIBRE BLOWING

Up to

Through underground ducts

Pneumatic power supports long-distance fibre installation.

VEHICLE SIZE

3.5

tonnes GVW

Compact utility vehicle

Smaller platform supports work on minor roads and in confined spaces.

LARGER VEHICLES

7.5–10

tonnes GVW

Previous vehicle class

Larger cabling units were suitable for motorways and major roads.

Impact and Results

The vehicle solution extended fibre installation capabilities beyond larger roads and into locations where heavier cabling vehicles could be difficult to operate.Key benefits documented in the case study include:

Smaller vehicle platform: a 3.5-ton GVW van provides improved suitability for minor roads and confined spaces.
Fibre blowing capability: pneumatic equipment can blow fibre optic cable through underground ducts for distances up to 1 km.
Multiple power systems: pneumatic, hydraulic and electrical capabilities are integrated into the utility vehicle.
Winching support: hydraulic power supports removal of existing underground cable.
Duct preparation: a hydraulically powered rodding machine clears ducts ahead of new cable installation.
Winch load monitoring: a load-cell system displays pulling force and stops the winch at maximum pull.
Additional field equipment support: onboard electrical power can support fusion welding equipment, water pumps and emergency lighting.

Key Takeaways

Fibre optic installation vehicles can combine compressed air, hydraulics and electrical power within one platform.
Reducing vehicle size from larger 7.5- and 10-ton units to a 3.5-ton GVW van provides greater flexibility for minor roads and confined areas.
Compressed air can support fibre blowing through underground ducts over distances of up to 1 km.
Hydraulic systems can power cable winches, duct-clearing equipment and hand tools.
Integrated electrical generation supports essential equipment used at installation and maintenance sites.
Load-cell monitoring provides operators with greater visibility of winch pulling force.
The case study demonstrates how specialist driveline systems can adapt telecommunications maintenance equipment to different vehicle sizes and operating environments.

Download the Fibre Optic Installation Vehicle Case Study

Explore how British Telecom and Gardner Denver combined pneumatic, hydraulic and electrical technologies to create versatile vehicles for fibre optic cable installation and maintenance.

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Frequently Asked Questions

In this application, the vehicle combines pneumatic, hydraulic and electrical systems. These systems support fibre blowing, winching, duct preparation, hydraulic tools, fusion welding equipment, water pumps and emergency lighting.

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Fibre Optic Cable Installation Vehicle for Confined Spaces