Oh really? Someone told me that it was because they have components on the roof (like Leyland National buses) that raise them up to 13 foot. Are there some steep gradients around Furness Vale?I'm not overly familiar with that line, to be honest.
Yes, the Buxton line is steeply graded. The summit is at Dove Holes. It's a stiff climb to Dove Holes from either side. I can't remember the figures but steeper than 1:100, on a curvy route and one that often has wet rails thanks to hill country weather. I think Pacers simply lack the traction to be reliable, so they're banned. I remember Pacers being tried on the Manchester-Glossop/Hadfield line when there was a shortage of EMUs once. Glossop is a bit like Buxton - a steep climb out of the terminus on curvy track, often wet. The Pacers couldn't cope, so they're banned from Glossop too, but as it's electrified that's not normally a limitation.