Introduction
Electric traction is used to eliminate smoke emissions and take advantage of the high efficiency of electric motors. However, the cost of railway electrification — both in terms of installation and long-term maintenance — is significant.
For this reason, only heavily trafficked lines are typically electrified.
DC and AC Current
Electrified railway lines are typically powered by either direct current (DC) or alternating current (AC).
DC Systems operate at relatively low voltage (between 600 and 3000 volts).
These systems require high current, which means that power losses along the line must be carefully managed and the entire electrical system must be capable of dissipating the energy effectively.AC Systems use higher voltages than DC.
For the same power, higher voltage results in lower current, which significantly reduces power losses. AC is therefore more efficient over long distances.
Main Role of a Mast (Pole)
The main function of an overhead line mast (pole) is to support and maintain the position of the catenary.
The catenary must follow a predefined path above the track to ensure reliable contact with the pantograph and to minimize wear on both components.
This is defined during the design phase by specifying:
The height of the contact wire (measured from the top of the rail)
The stagger, or horizontal offset of the wire from the track centerline
To reduce wear on the pantograph, the overhead wire is intentionally positioned in a zig-zag pattern within acceptable limits relative to the track axis.
Numbering of OHL Pole
Overhead line (OHL) poles also serve to indicate track kilometerage and to identify overhead line sections.
Typically, there are 15 to 18 poles per kilometer
Each pole is given a serial number, starting from the kilometer post
The number is displayed in two parts: Top: the kilometer marker, Bottom: the pole’s serial number
Example:70/1 = First pole after kilometer post 70, on the Up line
Single Line Sections
In single-line sections (where no future doubling is planned), poles are numbered progressively in the direction of increasing kilometerage:
Double Line Sections
In double-line sections:
Poles on the Up line are given odd numbers:
70/01,70/03,70/05, etc.Poles on the Down line are given even numbers:
70/02,70/04,70/06, etc.
Here, 1 and 2 represent the first poles after the kilometer post.
If span lengths on the Up and Down lines differ, and poles are not aligned, numbering should ensure that a higher serial number does not appear at a lower kilometerage.
Conclusion
ADTS provides advanced systems for the monitoring of overhead catenary lines, capable of measuring contact wire height, stagger and optionally wire wear.
In addition, dedicated solutions are available for the detection and counting of electric poles, supporting asset management, infrastructure verification and compliance with line geometry standards.
These tools are essential for ensuring safe and efficient operation across electrified railway networks.