Cable safety system

Abstract

A safety system including cables and support posts is provided. The safety system may be used to prevent vehicles from impacting with an associated roadside hazard. The safety system will typically maintain engagement between associated cables and support posts for a longer period of time as the posts are bent during a vehicle impact.

1 . A method of designing and installing a cable safety system adjacent to a roadway comprising: 
 conducting vehicle impact tests to determine cable deflection for three or more different spacings between support posts;    forming at least one graph showing deflection versus post spacing based on the vehicle impact tests;    using at least one graph of deflection versus post spacing to determine optimum post spacing for the cable safety system;    installing a plurality of posts proximate to the roadway with the posts spaced from each other with the optimum post spacing; and    releasably engaging at least two cables with respective slots formed in each of the posts to prevent a vehicle from leaving the roadway.    
     
     
         2 . The method of  claim 1 , further comprising: 
 placing at least a first cable, a second cable, and a third cable within the respective slot formed in each post;    placing a first spacer within each post between the first cable and the second cable; and    placing a second spacer within each post between the second cable and the third cable.    
     
     
         3 . The method of  claim 1 , further comprising: 
 placing at least a first cable, a second cable, and a third cable within the respective slot formed in each post;    placing a spacer within each post; and    respectively engaging a first recess, a second recess and a third recess formed in the spacer with the respective first cable, second cable and third cable to maintain desired spacing between the cables within each slot.    
     
     
         4 . The method of  claim 1  further comprising: 
 forming each post with a generally C-shaped cross section;    installing at least a first cable, a second cable, and a third cable disposed within each slot;    installing a single spacer disposed within the generally C-shaped cross section of each post; and    engaging the first cable, the second cable and the third cable with each spacer to maintain desired vertical spacing therebetween.    
     
     
         5 . The method of  claim 1  further comprising: 
 forming an insert defined in part by a first end and a second end;    forming a first recess disposed in the first end and a second recess disposed in the second end;    forming a third recess disposed in the insert spaced from the first end and the second end with the distance between the first recess and the second recess and the distance between the first recess and the third recess selected to correspond with desired vertical spacing between the first cable, the second cable and the third cable; and    positioning a first cable, a second cable and a third cable relative to each other when the cables are disposed within each slot formed in a support post.    
     
     
         6 . The method of  claim 5  further comprising forming the insert with a generally I-shaped cross section.  
     
     
         7 . The method of  claim 5  further comprising forming the insert at least in part from recycled material.  
     
     
         8 . The method of  claim 1  further comprising forming at least one of the posts with a cross section defined in part by a generally straight segment with respective curved segments disposed on each end of the straight segment.  
     
     
         9 . The method of  claim 1  further comprising forming at least one of the posts with a cross section selected from the group consisting of generally an oval, a circle, a square, a rectangle, a C-shape, an N-shape, a Z-shape, a V-shape, an I-shape, and an M-shape.  
     
     
         10 . A method of forming and installing a cable safety system adjacent to a roadway comprising: 
 forming a plurality of support posts with a respective slot disposed in each support post and sized to receive at least two cables;    forming each slot with a generally elongated, U-shaped configuration defined in part by a first edge, a second edge and a bottom; and    forming respective restrictions on the first edge of each slot and forming respective restrictions on the second edge of each slot whereby the restrictions cooperate with each other to provide optimum resistance for disengagement of the cables from each slot as the respective support post is bent from a generally vertical position towards a generally horizontal position to increase the length of time the cables are retained in each slot during a vehicle impact with the cable safety system.    
     
     
         11 . The method of  claim 10 , further comprising: 
 installing the support posts with an optimum spacing between each support post to prevent a vehicle from leaving the roadway; and    installing at least two cables extending through the respective slot formed in each support post.    
     
     
         12 . The method of  claim 10 , further comprising: 
 placing at least a first cable, a second cable, and a third cable within the respective slot formed in each support post;    placing a first spacer at each support post between the first cable and the second cable; and    placing a second spacer at each support post between the second cable and the third cable.    
     
     
         13 . The method of  claim 10  further comprising: 
 forming each support post with a generally I-shaped cross section; and    installing at least a first cable, a second cable, and a third cable within each slot.    
     
     
         14 . The method of  claim 10  further comprising: 
 forming an insert defined in part by a first end and a second end;    forming a first recess disposed in the first end and a second recess disposed in the second end;    forming a third recess disposed in the insert spaced from the first end and the second end with the distance between the first recess and the second recess and the distance between the first recess and the third recess selected to correspond with desired vertical spacing between the first cable, the second cable and the third cable; and    positioning a first cable, a second cable and a third cable relative to each other when the cables are disposed within each slot formed in each support post.    
     
     
         15 . The method of  claim 14  further comprising forming the insert with a generally I-shaped cross section.  
     
     
         16 . The method of  claim 14  further comprising forming the insert at least in part from recycled material.  
     
     
         17 . The method of  claim 10  further comprising forming each support post having a generally I-shaped cross section.  
     
     
         18 . The method of  claim 10  further comprising forming at least one of the support posts with a cross section selected from the group consisting of generally an oval, a circle, a square, a rectangle, a C-shape, an N-shape, a Z-shape, a V-shape, and an M-shape.  
     
     
         19 . A safety barrier installed adjacent to a roadway comprising: 
 a plurality of posts spaced from each other and disposed adjacent to the roadway;    each post having a generally I-shaped cross section defined in part by a web;    each post having one slot formed in the web of the post and extending from an upper end of the post;    at least two cables releasably engaged with and supported by the posts;    each slot having a first edge and a second edge with respective sloping surfaces operable to slidably receive the at least two cables therein;    the sloping surfaces on the first edge of each slot providing a first projection;    the sloping surfaces on the second edge of each slot providing a second projection;    the first projection and the second projection cooperating with each other to form a respective restriction within each slot;    a gap formed between the first projection and the second projection which is greater than an outside diameter of the at least two cables;    the cables disposed within each slot of the posts; and    the posts and the at least two cables cooperating with each other to prevent a vehicle from leaving the roadway.    
     
     
         20 . The safety barrier of  claim 19  further comprising a respective cap releasably secured with an upper end of each post.  
     
     
         21 . The safety barrier of  claim 19  further comprising 
 the first edge of each slot having respective sloping surfaces which form a first projection, a second projection and a third projection extending from the first edge;    the second edge of each slot having respective sloping surfaces which form a first projection, a second projection and a third projection extending from the second edge;    the projections on the first edge cooperating with the projections of the second edge to form a respective first restriction, second restriction and a third restriction in each slot; and    at least a first cable, a second cable, and a third cable disposed with each slot.