(WHAS11) - With two civil lawsuits filed against the Louisville Zoo, the zoo director says he can't say much about the derailment which sent 22 passengers to the hospital.
Zoo Director, John Walczak says he still doesn't know what caused the accident.
The images of the derailment caught the attention of viewers around the country and one detail of WHAS11's video especially caught the attention of a train expert.
Walczak says state investigators are looking into all mechanical factors, including whether the train cars were attached correctly to the train wheels.
Because the wheels, called trucks, ended up apart from the coaches after the derailment. That's what got the attention of an expert on miniature trains.
David Sclavi is the owner of a New Jersey miniature train company.
He posts information and tutorials for train hobbyists on YouTube.
Now Sclavi has told state investigators what he observed, that the zoo train appears to be missing what he calls "keeper plates," that connect the train cars to the wheels.
Sclavi estimates each wheel set weighs at least 1,500 pounds and if connected, acts as a counter-weight to the weight of the passengers.
Sclavi warns his theory is only based on our photos and Sky11 video, but it is based on 40 years of experience.
An executive with Chance Rides Manufacturing, the Kansas company that made the zoo train says the trains do, in fact, come with what are called "truck to frame hooks" that are designed for the installation and removal of trains.
Jeff Roth of chance rides manufacturing, says though the hooks may have the incidental effect of giving the coaches a lower center of gravity, that is not their design.