School buses are a safe method of transport. In fact, the safety of school transport is comparable to that of a private car, providing we are dealing with a service that includes all the compulsory requirements of current legislation.
Moreover, school transport has a fundamental advantage over private car use, namely that it does not increase congestion in the school's vicinity.
When transporting young children, school buses must be equipped with seat belts. The teachers, monitors and drivers are responsible for ensuring that the seat belts are properly fastened and that the children remain in their seats and that their seats are in the correct position.
Spanish legislation does not cover children under three years old. This means that it does not specify that these very young children must be using a specific restraint system on the bus. This seems contradictory, given that these children are the most vulnerable in a crash.
Although it is certainly the case that these are children who are not yet of school age, they might also be using the buses for one reason or another. There is a specific piece of legislation pertaining to school-age children, i.e. those over three years old: the General Traffic Rules stipulate that on buses (and, in general, all vehicles used to transport passengers with more than 9 seats), these children must use approved child restraint systems suitable for their size and weight. When these systems are not available, the seat belts must be used, provided that they are suitable for the child's height and weight.
In conclusion, using a child car seat is neither prohibited nor compulsory. It is something which is dependent on the availability of a suitable seat that can be installed on the bus and which will not encroach on adjacent seats or hamper the safe movement of other passengers.
This means that we can indeed install a child car seat on the school bus, providing that the aforementioned requirements are fulfilled. Logically, it is not the most practical solution since we have to install it and take it out every time the child uses school transport if we only have one seat.
There are seats on the market that have been approved for use on buses in Europe which equate to booster seats, and are designed for children from 15 to 27 kilos and are foldable, flexible and easy to transport.
We should be aware of how difficult it is to install a CRS on a school bus. Apart from having to install and uninstall it, (something which is theoretically possible to do) the vast majority of buses have two-point seat belts, which makes it difficult to secure the child seat, especially those designed for very young children.
Depending on the child's age, they can start to use a two-point seat belt. However, they will be less protected than if they are in a child restraint system. In the case of three-point belts, it is vital to have at least a booster seat in order for the belt to correctly secure the child and not injure them.