The Short Answer
There are three broad approaches to carrying safety information between a tractor unit and trailer:
- Dedicated data cabling
- Wireless communication
- Vehicle Safety Powerline Communication (VSPC)
Dedicated data cabling creates a separate physical data pathway and, where that pathway needs to cross the tractor/trailer interface, may require an additional data suzie or other external connector.
Wireless systems transmit the information through the air, whilst VSPC uses the vehicle’s existing OEM power wiring as the communication pathway.
Each approach can transfer information between connected vehicle sections, but differs in the additional hardware, connections and operational processes it requires.
Why Is Trailer Communication Different?
Unlike rigid vehicles, articulated vehicles are designed to separate.
Cameras, sensors and other safety equipment may be mounted on the trailer, whilst the monitor, warning device or recording system that uses their information may be located on the tractor unit.
The communication system therefore has to transfer information across the point at which the two vehicles connect whilst still allowing tractors and trailers to be exchanged throughout normal operation.
That creates an engineering challenge which can be addressed in several different ways.
1. Dedicated Data Cabling
One approach is to provide dedicated cabling specifically for carrying safety information.
Unlike the vehicle’s existing power wiring, this creates a separate physical data pathway for the safety system. Depending on the application, dedicated cabling may run through the tractor, trailer or both.
Where that pathway needs to cross the separable connection between tractor and trailer, an additional data suzie or other external connector may be required. This provides a means of making and breaking the dedicated data connection as the tractor and trailer are coupled and uncoupled.
A dedicated wired connection can provide a direct physical communication pathway, but introduces additional cabling and, where required, another external connection that must be routed, protected and maintained.
This approach can work effectively, particularly where vehicle combinations remain relatively fixed. Where trailers are exchanged frequently, any additional connection across the tractor/trailer interface must also be managed each time the combination changes.
2. Wireless Communication
Wireless systems remove the need for a physical communication connection across the tractor/trailer interface by transmitting information wirelessly.
This can reduce the amount of additional physical infrastructure required between the two vehicles and can be useful where installing a dedicated connection would be difficult or undesirable.
However, fleets should also consider how the system identifies and connects to the correct equipment as tractor and trailer combinations change, whether any pairing or configuration is required, and how the wireless connection will behave within the intended operating environment.
As with any communication method, suitability depends on the application rather than wireless being inherently better or worse than a wired approach.
3. Vehicle Safety Powerline Communication (VSPC)
Vehicle Safety Powerline Communication takes a different approach again.
Rather than installing a separate full-length data pathway or transmitting information wirelessly between the tractor and trailer, VSPC uses the vehicle’s existing OEM power wiring as the communication pathway.
The wiring continues to perform its normal electrical function whilst also providing the pathway over which appropriately encoded safety information is communicated.
X-Wire is SCC’s patented implementation of Vehicle Safety Powerline Communication.
In a typical articulated application, this allows X-Wire-enabled safety systems to establish communication through the vehicle’s normal electrical connection as part of the coupling process, without requiring an additional data suzie or wireless pairing process.
How Do The Different Approaches Compare?
The important distinction is not simply whether each approach can transfer information. It is how that communication is achieved and what the method requires from the vehicle and its operation.
| Communication Approach | How It Communicates | Typical Considerations |
|---|---|---|
| Dedicated data cabling | Separate physical data pathway, potentially including an additional data suzie or connector across the tractor/trailer interface | Cable routing, protection, external connections and maintenance |
| Wireless communication | Wireless transmission between vehicle sections | Connection management, pairing where applicable and operating environment |
| Vehicle Safety Powerline Communication | Existing OEM power wiring | Integration with the vehicle’s existing electrical infrastructure |
Which Communication Approach Is Best?
There is no universally correct answer.
The most appropriate communication architecture depends on the vehicles, safety equipment and way the fleet actually operates.
Useful questions include:
- How frequently are tractors and trailers interchanged?
- What safety information needs to pass between them?
- What additional connections will drivers need to make?
- What infrastructure needs to be installed on the tractor and trailer?
- Does any pairing, selection or configuration need to take place when combinations change?
- How will the communication system be inspected and maintained?
- How easily can additional vehicles or safety technologies be incorporated later?
A fleet operating permanently coupled combinations may place different demands on the communication architecture from one in which tractors and trailers are exchanged several times during a working day.
The right approach is therefore the one that meets the technical requirement whilst fitting the way the fleet actually operates.
Why Does Understanding The Difference Matter?
When comparing vehicle safety systems, it is easy to concentrate on the visible equipment: the camera, sensor, monitor or warning device.
But where that equipment is distributed across a tractor and trailer, the communication architecture connecting it becomes part of the overall system.
Different approaches can affect installation, driver interaction, maintenance and what happens when combinations change. They can also influence how easily further vehicles or safety technologies can be incorporated later.
Understanding the communication method therefore allows fleets to look beyond individual product specifications and consider how the complete system will work throughout its operational life.
Final Thoughts
There are several ways of transferring safety information between a tractor unit and trailer, and each solves the same fundamental problem differently.
Dedicated data cabling creates a separate physical pathway and may require an additional data suzie or other connector where that pathway crosses the tractor/trailer interface. Wireless systems transmit information without a physical communication connection across that interface, whilst Vehicle Safety Powerline Communication uses existing OEM power wiring to provide the communication pathway.
None should be judged solely by whether information can be transferred from one vehicle to the other.
For fleets, the more useful question is what each approach requires to keep that communication working as tractors, trailers and operating requirements change.
