107 kilometres on the map, 2,568 kilometres in the air

A transmission line is usually introduced through its route length.

The Rural Damascus–Daraa 400 kV double-circuit transmission line extended for approximately 107 kilometres between the two Syrian governorates. That figure describes the distance travelled by the corridor from one end to the other.

It does not describe the total amount of electrical material suspended above it.

Across the same route, approximately 2,568 kilometres of phase conductor were installed.

The project also included around 107 kilometres of conventional earthwire and a similar length of Optical Ground Wire.

From the ground, these cables appear to follow one route.

Electrically and mechanically, they form several parallel systems operating at the same time.

The project, delivered by International Consolidated Contractors Offshore SAL, therefore involved much more than stretching a cable between two locations. It required the precise arrangement of conductors across 321 towers, with every span forming part of a continuous 400 kV system.

Route length and conductor length describe different things

The 107-kilometre figure measures geography.

The 2,568-kilometre figure measures installed conductor.

A double-circuit transmission line carries two separate electrical circuits along the same corridor. Each circuit contains three electrical phases.

But each phase does not necessarily consist of only one visible conductor.

At extra-high voltage, phases can be formed from groups of smaller conductors arranged together as a bundle. These individual elements follow the complete route in parallel.

That is how a line occupying 107 kilometres of land can require many times that distance in conductor material.

The result is not one cable running from Rural Damascus to Daraa.

It is a carefully spaced system of conductors extending across the corridor, phase after phase and circuit after circuit.

Two circuits on one set of towers

The project's double-circuit arrangement allowed two three-phase systems to use the same transmission corridor.

Both circuits were supported by the same sequence of 321 steel lattice towers, but they remained electrically distinct.

This configuration concentrates more transmission infrastructure within one route. It also makes the towers more complex than structures carrying a single circuit.

Each tower must provide the required separation:

• between the three phases of one circuit;
• between one circuit and the other;
• between energised conductors and the steel structure;
• between the conductors and the ground;
• between the phase system and the protective wires above it.

The arrangement must remain safe under changing temperature, wind and operating conditions.

A tower is therefore not simply a support.

It is the structure that preserves the electrical geometry of the line.

The conductors were designed to operate as bundles

The project included approximately 8,200 bundle spacers.

Their presence reveals that the phase conductors were not treated as isolated wires. They were arranged in groups whose relative positions had to remain controlled.

Bundle spacers are installed between the individual conductors forming the same electrical phase.

They hold those conductors apart at a defined distance.

Without that separation, the conductors could move towards one another, clash or lose the geometry required by the line's electrical design.

The spacers also allow the separate elements to behave as one organised phase bundle rather than as unrelated cables exposed to wind and movement.

This is an example of small equipment governing very large infrastructure.

A bundle spacer is insignificant compared with a transmission tower.

Yet thousands of them are required to keep the conductor arrangement stable along the full route.

Why multiple conductors are used within one phase

At 400 kV, the electrical behaviour around a conductor becomes an important part of line design.

Using multiple conductors within a phase increases the effective size of the phase bundle.

This can support the line's electrical performance while distributing current across several conductor elements.

Bundled arrangements are also used to manage electric-field effects around extra-high-voltage conductors.

The design must balance:

• electrical performance;
• mechanical strength;
• conductor weight;
• wind response;
• tower geometry;
• installation requirements.

The bundle is therefore not simply a way of adding more metal.

It is part of the complete electrical design of the 400 kV line.

The conductors are always moving

A transmission conductor may look motionless from a distance.

In practice, it responds continuously to its environment.

Wind can produce small, repeated oscillations.

Temperature changes cause conductors to expand and contract.

Different operating conditions can change conductor temperature and sag.

These movements are expected, but they must be controlled.

The Rural Damascus–Daraa project used approximately 5,400 vibration dampers across the line.

Vibration dampers absorb and reduce repeated conductor movement caused by wind.

This matters because even small oscillations can create repeated stress at points where a conductor is attached to fittings or insulator assemblies.

One movement may be harmless.

Thousands or millions of repeated movements over time can produce fatigue.

The dampers help protect the conductor and its connections from that cumulative mechanical stress.

Sag was calculated, not removed

The conductors between two towers do not form a straight horizontal line.

They hang in a curve known as sag.

Sag is necessary.

A conductor pulled completely straight would create excessive tension on the conductor, towers and foundations. A conductor allowed to hang too low could reduce the required clearance from the ground or objects beneath the line.

The correct sag sits between those two risks.

It must account for:

• the distance between towers;
• conductor weight;
• installation temperature;
• expected operating temperature;
• wind and weather conditions;
• required ground clearance.

During construction, the conductors had to be tensioned and adjusted span by span.

The line could not be accepted simply because the cables had been pulled across the towers.

Their final position had to match the approved design conditions.

Four tower families controlled the route

The Rural Damascus–Daraa corridor used 321 tower positions, but the towers did not all perform the same duty.

The project included:

The conductor system interacts differently with each tower type.

On straight sections, suspension towers support the conductors while allowing the route to continue with limited directional change.

Corner towers manage the forces created when the alignment turns.

Heavy-tension towers restrain greater mechanical loads and divide the route into controlled tension sections.

Terminal towers anchor the conductor system at its endpoints or transition points.

The conductors may be continuous across the corridor, but the forces within them are managed through these different structural roles.

Where the route bends, the tower must resist more than downward weight.

It must also resist the sideways pull created by the change in direction.

Where a tension section ends, the structure must hold forces that would otherwise continue into the next span.

The conductor system therefore shaped the tower schedule.

Insulators connected the conductors without carrying electricity into the towers

The steel towers had to support the phase conductors without becoming part of the energised path.

Insulator strings created that separation.

They carried mechanical load while preventing the 400 kV system from connecting electrically to the tower steel.

Different tower duties required different insulator arrangements.

Suspension positions support conductors differently from tension and terminal positions.

At a suspension tower, the conductor continues through the structure.

At a tension or terminal tower, the insulator assembly may also have to resist a much greater horizontal pull.

The insulators were therefore both electrical and structural components.

They separated voltage.

They also held the conductor system in place.

The two upper wires had different responsibilities

Above the phase conductors, the project installed two additional systems.

One was a conventional earthwire.

The other was Optical Ground Wire, commonly known as OPGW.

Both were positioned to contribute to lightning protection.

Because they run above the energised conductors, they provide a preferred interception point for direct lightning strikes.

The OPGW also carried optical fibres.

Those fibres created a communication route along the same corridor used for electricity transmission.

The line therefore contained two networks.

The visible phase conductors moved electrical power.

The optical fibres carried information used for communication, monitoring and protection between connected grid facilities.

The OPGW followed the physical route of the transmission line, but its purpose was digital as well as electrical.

Installing the conductors required a controlled sequence

Conductor stringing could only begin after the supporting infrastructure was ready.

The necessary towers had to be erected.

Insulators and stringing equipment had to be installed.

The relevant tension sections had to be prepared.

Temporary equipment was then used to draw conductors through successive tower positions.

The process had to prevent the conductors from being dragged directly across the ground or damaged during installation.

After pulling, the conductors were tensioned to the required sag.

Bundle spacers and vibration dampers were then installed at their specified locations.

Connections, clamps and fittings had to be completed and inspected.

The earthwire and OPGW required their own installation and verification procedures.

The work therefore progressed as a chain of dependent activities.

A finished tower did not mean the span was ready.

A pulled conductor did not mean the circuit was complete.

The line became operational only when the civil, structural, electrical and communication systems had been connected and verified together.

Continuity had to be proven

A transmission line of this scale cannot be judged by appearance alone.

The conductor system required inspection across the route.

Teams had to verify:

• conductor installation;
• sag and clearance;
• clamps and fittings;
• insulator assemblies;
• bundle spacers;
• vibration dampers;
• earthwire connections;
• OPGW continuity.

The optical fibres inside the OPGW also had to be tested.

A cable could appear physically complete while still containing a communication fault, damaged fibre or excessive signal loss.

Testing confirmed that the line did not merely extend across the landscape.

It functioned as one continuous electrical and communication corridor.

ICCO's work extended from design to handover

International Consolidated Contractors Offshore SAL delivered the Rural Damascus–Daraa project through a scope covering engineering, procurement, civil construction, tower erection, conductor stringing, grounding, testing and final integration.

The conductor system required coordination across almost every part of that scope.

Tower positions determined span lengths.

Tower designs established attachment points and clearances.

Foundations resisted the forces created by tensioned conductors.

Insulators separated the electrical system from the structures.

Spacers preserved the phase bundles.

Dampers controlled repeated movement.

Earthwire and OPGW protected and connected the route.

None of these systems could be designed or installed in isolation.

The project commenced in August 2018, reached mechanical completion in January 2021 and proceeded to final handover in February 2021.

By that stage, thousands of separate components had been assembled into a single operating line.

The project was longer than its route

The Rural Damascus–Daraa transmission line occupied approximately 107 kilometres on the map.

That is the number used to describe where the project went.

The 2,568 kilometres of phase conductor describe what had to be placed above that route to make it electrically useful.

Between those two figures sits the complete engineering of the line:

Two circuits.

Three phases per circuit.

Bundled conductors.

Thousands of spacers and dampers.

Four tower families.

Protective earthwire.

A fibre-optic communication path.

The route length tells us the distance between the project's ends.

The conductor length tells us how much infrastructure was required to connect them.