@def start	= mSec()	# start time
@def mod_count	= 0		# modification counter

@function isRoad # flag
    @pdef t = $1 & 0x1f
    @return t <= 0x05 || t == 0x17 || t == 0x1d
@endfunction

@for t=0;tri$n()-1
    @if !isRoad(tri$flag(t,2))
	@def status = tri$remove(t)
    @endif
@endfor

@echo "  - " mod_count " of " tri$n() " triangles lowered in " (mSec()-start) " msec."