More specifically, the track ballast constitutes the trackbed upon which sleepers or railroad ties are laid.

更具体地说，轨道道砟构成铺设枕木或枕木的轨道床。

As you may have seen, these stones are packed below, between and around the railroad ties.

如你所见，这些石头被堆积在铁路枕木下面和周围。