I'm not quite sure how subtracting 3/8 from 5/8 is relevant at all.

If the trestle is 1000 yards long, and the train is 1/4 mile away from the start of the trestle (our guy has bad hearing), then he will have to run 375 yards in 15 seconds, or 625 yards in just under a minute. Running 15 mph just ain't gonna cut it.

Or, the train could be 2 miles away (blowing his whistle real loud), and the trestle could be only 30 yards long. In that case, he can leisurely stroll to either side.

Just these two examples show the length of the trestle and the distance of the train are not optional information, imho.

__________________
Jeremy Gage
First Baptist Church
Durham, NC

"No heart can conceive that treasury of mercies which lies in this one privilege, in having liberty and ability to approach unto God at all times, according to his mind and will." - John Owen