Multi-Rail Parapet

Abstract

A vehicle safety parapet comprises a plurality of rails ( 18, 24, 28 ) supported at varying heights on uprights ( 12 ). A first of the rails comprises a steel box-section supported at each upright by bracketing means ( 20 ) configured to collapse when a horizontal impact load is applied to the rail, such that the first rail is displaced towards the upright. At least one other rail extends from the uprights by a greater distance than the first rail when the bracketing means has collapsed.

1 - 16 . (canceled) 
   
   
       17 . A vehicle safety parapet comprising a plurality of rails supported at varying heights on uprights, including:
 a first rail comprising a steel box-section supported at each upright by bracketing means configured to collapse when a horizontal load from a vehicle impacting the parapet is applied to the rail such that the first rail is displaced towards the uprights; and   a second rail mounted at a height at which an impacting vehicle of a first size would be expected to impact the second rail after the first rail has been displaced towards said uprights,   wherein the first and second rails extend substantially the same distance from the uprights.   
   
   
       18 . The vehicle safety parapet of claim  1 , wherein the first rail is a lower rail, the second rail being mounted above the first rail. 
   
   
       19 . The vehicle safety parapet of claim  1  wherein the second rail comprises a steel box-section supported at each upright by bracketing means configured to collapse when a horizontal load from a vehicle impacting the parapet is applied to the rail such that the second rail is displaced towards the uprights; and
 the second rail mounted at a height at which an impacting vehicle of a second size would be expected to impact the second rail first.   
   
   
       20 . The vehicle safety parapet of claim  1 , wherein the second rail has a trapezoidal section with the shorter parallel side facing the roadway. 
   
   
       21 . The vehicle safety parapet of claim  4 , wherein at least part of the longer parallel side of the second rail, facing away from the roadway, is open. 
   
   
       22 . The vehicle safety parapet of claim  1 , wherein the bracket means comprises at least one sheet metal cleat member operable to collapse by plastic deformation. 
   
   
       23 . The vehicle safety parapet of claim  6 , wherein the cleat member has a vertical portion for securing to the upright and a horizontal portion for securing to the first rail. 
   
   
       24 . The vehicle safety parapet of claim  7 , wherein the cleat further comprises an inter-connecting portion adjoining the horizontal and vertical portions at bends such that the plastic deformation occurs at one or more of the bends. 
   
   
       25 . The vehicle safety parapet of claim  8 , wherein, when mounted to the upright, the inter-connecting portion is set at an angle to both the upright and the rail. 
   
   
       26 . The vehicle safety parapet of claim  6 , wherein the bracket means comprises a pair of cleats mounted to the upright one above the other, a lower cleat supporting the rail from below, and an upper cleat supporting the rail from above. 
   
   
       27 . The vehicle safety parapet of claim  10 , wherein both cleats have the same dimensions and are mounted in the same orientation. 
   
   
       28 . The vehicle safety parapet of claim  3 , wherein the second rail is another rail having the same, or similar construction and collapsible support bracketing as the first rail. 
   
   
       29 . The vehicle safety parapet of claim  12 , wherein the steel box-section of the first and/or the second rail is a square section. 
   
   
       30 . The vehicle safety parapet of claim  12 , wherein the steel box section is rectangular. 
   
   
       31 . The vehicle safety parapet of claim  14 , wherein the rectangular box section is orientated with the longer side of the rectangle horizontal. 
   
   
       32 . The vehicle safety parapet of claim  1 , wherein a third rail is provided mounted above the first and second rails. 
   
   
       33 . A vehicle safety parapet comprising a plurality of rails supported on uprights, each rail being supported at a different height, the safety parapet including:
 first and second rails, each comprising a steel box-section supported at each upright by bracketing means configured to collapse when a horizontal load from a vehicle impacting the parapet is applied to the rail such that the rail is displaced towards the uprights,   wherein the second rail is mounted at a height at which an impacting vehicle of a first size would be expected to impact the second rail after the first rail has been displaced towards said uprights, and at which an impacting vehicle of a second size would be expected to impact the second rail first,   wherein the first and second rails extend substantially the same distance from the uprights.   
   
   
       34 . A vehicle safety parapet comprising a plurality of rails supported at varying heights on uprights, including:
 a first rail comprising a steel box-section supported at each upright by bracketing means configured to collapse when a horizontal load from a vehicle impacting the parapet is applied to the rail such that the first rail is displaced towards the uprights; and   a second rail mounted at a height at which an impacting vehicle of a first size would be expected to impact the second rail after the first rail has been displaced towards said uprights,   wherein the bracket means comprises at least one sheet metal cleat member having a vertical portion for securing to the upright, a horizontal portion for securing to the rail and an inter-connecting portion adjoining the horizontal and vertical portions at bends such that the bracket means collapses by plastic deformation occurring at one or more of the bends.