Evacuation of mixed populations from trains on bridges

An understanding of human evacuation dynamics and performance are important when designing complex buildings such as bridges and when applying performance-based codes in order to reduce the risk of exposing occupants to critical conditions in case of fire. The majority of previous studies deal with the evacuation behavior of abled bodied homogeneous groups. Hence, a significant part of the population is poorly described such as are people with impairments which are about 10%-21% of the world's population, furthermore elderly people, giving an additional 10% and 20% of the population are aged below 15 years. The discussion of "equal access" is only followed slowly by the demand on "equal egress". However, the passengers on trains on bridges are rarely homogeneous mixture. At the same time equal egress is far from assured today. In this paper the evacuation of mixed populations from trains on bridges are considered. The populations applied in the experiment are mixed according to a composition corresponding to the population of Denmark. The study has the following findings: the total evacuation times increase with a factor 1.5 when accounting for a mixed population comprehending a variety of age and impairments. The seating of the people in the train affects these times. More real data on subgroups of a mixed population are needed as input and validation data for models like STEPS.