Originally Posted by
Retro Grouch
Suppose the "gate" consisted of a steel cable strung across the trail.
Not impossible, but something like a single bar, perhaps 1-1 1/2 feet above the ground so a bike can be lifted over it (while a car can not) is more likely (and perfect to go head first over). Seems a 'smart' solution, until one realizes under the right conditions such can be difficult to see.
Things like this are pretty common on the entryways to many of the bike paths that parallel store drains here in Los Angeles. But with once crucial difference to this case (it seems). The barriers are at points where a bike would be stoping anyway. The ones I remember are mainly at the top of ramps going up to street level.