What Are the Differences Between R159 MOIS, BSIS, CMS, and UN R46?

I meet many users who feel confused about these standards. I was the same at first. I saw the names, and everything looked similar. I worried about choosing the wrong system, failing compliance, or spending money on something useless. This pushed me to sort out the differences in the simplest way possible.

MOIS, BSIS, CMS, and UN R46 serve different safety goals. MOIS focuses on front blind-spot detection, BSIS focuses on the side, CMS replaces mirrors with cameras, and UN R46 defines the basic visibility requirements. These standards complement each other instead of replacing each other.

I want to break down each one in a clear and simple way, so you know exactly which standard matters for your fleet and why it matters now.

What Is R159 MOIS and How Does It Work?

I used to think MOIS worked like a simple front camera, but I later saw how many rules it actually covers. Many fleets misunderstand it and miss the real requirements.

MOIS is the EU system that detects pedestrians or vulnerable users in front of a truck or bus at low speed. It uses AI cameras or sensors to watch the front blind spot and warns the driver before a collision happens.

I learned how deep this topic goes when I helped a customer test MOIS on a 12-ton truck. The driver never noticed how large the front blind spot was. The system changed how safely he drove. Below is a simple breakdown.

MOIS Core Functions Explained

MOIS focuses only on the front zone. This is the first key difference from BSIS.

Why Is BSIS Different From MOIS?

I once thought MOIS and BSIS were the same thing in different names, until I saw fleets mix them up and install the wrong system. BSIS is for the side, not the front.

BSIS detects cyclists and pedestrians on the right side (or curb side) of large vehicles. It warns the driver during low-speed turning, helping prevent side-turn collisions.

I remember doing a demo for a customer who believed MOIS alone covered everything. When he saw BSIS detect cyclists staying quietly next to his truck, he understood why both systems exist. Here is the structure.

BSIS Core Functions Explained

MOIS covers the front.
BSIS covers the side.
They solve different risks.

What Does CMS Do and Why Is It Not a Detection System?

When I first heard “CMS,” I thought it offered AI detection like MOIS. I later learned I was very wrong. CMS replaces mirrors. It is not a pedestrian detection system.

CMS (Camera Monitoring System) uses cameras and displays to replace traditional mirrors. It improves visibility, reduces blind spots, and removes mirror vibration issues.

I tried CMS on a demo truck. The visibility at night surprised me. The camera showed more than a mirror ever could. But CMS alone cannot meet MOIS or BSIS safety requirements.

CMS Core Functions Explained

CMS gives visibility.
MOIS and BSIS give detection.
They are not interchangeable.

How Does UN R46 Connect Everything?

I saw many customers misunderstand UN R46. They often think UN R46 is a detection standard, but it is only a visibility standard. It defines the required visual fields that mirrors or CMS must cover.

UN R46 ensures that the driver always sees minimum required areas around the vehicle, either through mirrors or a CMS system.

Once I joined a compliance test where a mirror’s installation height failed by 4 cm. The truck had to redo the entire installation. It showed me how strict this standard is.

UN R46 Core Functions Explained

UN R46 is the foundation.
CMS builds on it.
MOIS and BSIS add active safety.

Conclusie

When I first tried to understand these standards, I also felt lost. Now I see each one covers its own part of the vehicle: MOIS watches the front, BSIS watches the side, CMS replaces mirrors, and UN R46 defines visibility. Together, they shape the new European safety system. If you want help building the right setup for your fleet, you can Get in touch with us anytime. I can share testing tips and sample configurations that work well in the real world.