What about heavy riders and riders of various sizes?
Most standards are based on “standard” adults weighing 170 pounds or children weighing 90 pounds (i.e., based on the ASTM standards). This is the required analysis for the forces on the rider’s body. In addition, the structural analysis of the “load and strength” of the ride must consider heavier rider weights.
The amusement ride and device design community is conscious that the upper bounds of rider weight considered in both of these analyses may need to be increased. However, accommodating larger riders is not a simple matter of making the restraint devices bigger. Many rides apply strong forces to the rider’s body. Force is the product of acceleration x mass. A body of higher weight is therefore exposed to higher forces. Restraint devices are not just an obstacle to securing a large body on a ride; they may actually be an essential screening tool to prevent people at risk from being exposed to risk that could overload their musculoskeletal system. This requires much more consideration, not just seat-belt extenders.
The increased awareness of accessibility allows more people with medical conditions and disabilities to come to public places and participate fully in society, and it is often difficult to know what the individual effect of a ride might be in those cases. We don’t want to encourage discrimination just to prevent the unknown. While a person who “looks disabled” might have no particular problem on a given ride, another person might have an undiagnosed medical condition that could be life-threatening under the conditions of the ride.