Addressing the initial Expo plan, Quimby told the commission that a street-level crossing at Farmdale would present "an unreasonably high safety risk" to Dorsey students, even at speeds as low as 10 mph.
A catastrophic accident could occur, he said, if a train derailed and went into a crowded pedestrian holding area or a train pushed a vehicle into the same place. A serious explosion, he said, could occur if a train collided with a truck or bus.
Quimby further testified that MTA's grade separation criteria appeared to be more concerned with operational convenience than safety.
Critics also say that students, adults and motorists can get around crossing gates and there are no assurances that train speeds through the intersection won't increase later. They note that serious accidents have occurred on the county's Gold Line and Blue Line light-rail systems at speeds of 15 mph or less.
"The entire community is put at risk by this train. It's jeopardizing everyone," testified Jevante Davis, a Dorsey student and captain of the varsity wrestling team. This issue "isn't going to be over until it [the train] is under."
Expo's supporters told the commission Tuesday night that light-rail lines have operated safely near schools for years and Expo's revised plan is a substantial improvement over earlier proposals, including one that called for the closure of the intersection and a pedestrian bridge.
"This will benefit students and the community," said Darrell Clarke of Friends 4 Expo Transit, who testified at Tuesday's hearing. "This will be safer than the Gold Line, which has had zero accident deaths."
The line's proponents also downplay Quimby's opinions, contending that his primary expertise is in freight and passenger train accidents, though he says he served as an expert witness for MTA in a lawsuit involving a light-rail crash. Samantha Bricker, an Expo spokeswoman, said his remarks are not applicable because light-rail trains go slower, stop quicker and derail less often.
"It's time to move forward. We've been dealing with this issue a long time," Bricker said. "We feel we've gone beyond what has been done on other light-rail lines."