Depending on the sizes, exterior stairs can handle a large flow of people during a evacuation.
In most evacuation situations there is a panic factor so the egress stairs need to be as safe and comfortable as possible to use. This can only be achieved with straight stair - flights and not with circular ones.
JOMY evacuation stairs are build from anodized aluminum so they resist harsh conditions without rusting.
JOMY fire stairs can come with grading floors so the snow will not rest on horizontal plates.