fig3 however it should be apparent that for example culvert structures 16 having a wide span relative to the width of the watercourse 12 such that the footers 40 are remote from the watercourse 12 permit the stream bed to be well below the footers 40 fig3 therefore represents but one of the vertical arrangements of such features since the culvert lacks a bottom portion flow through it is unimpeded by such a structure and furthermore cleaning of debris and of the watercourse 12 itself is greatly simplified the instant culvert design also enjoys a significant weight and thus material and cost reduction over conventional box culvert constructions such weight material and cost reductions devolve directly from the elimination of the bottom horizontal portion of the culvert since culverts are typically arranged such that their longer dimension is horizontal and since one of the longer horizontal portions has been eliminated by the instant invention the weight reduction enjoyed is typically at least 25 and generally greater the following table relates typical weight reductions of the instant invention relative to a conventional four wall standard box culvert ______________________________________ approx weight approx weightnom size st 39 d box culvert 3 wall structure feet lbs lin ft lbs lin ft ______________________________________10 u00d7 5 4400 290010 u00d7 7 4900 3460 10 u00d7 10 5650 424012 u00d7 6 6300 405012 u00d7 8 6900 4830 12 u00d7 12 8100 6070______________________________________ from the foregoing specification particularly the.