You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application No. 60/870,486 filed Dec. 18, 2006. 

   TECHNICAL FIELD 
   The present invention relates in general to bollards and more specifically to a bollard system that includes a mechanism to deter efforts to disable the bollard as a physical barrier. 
   BACKGROUND 
   There has been a long-felt need to provide barriers to protect secured areas from encroachment by motor vehicles. These secure areas vary in size and purpose and include by without limitation, high pedestrian areas proximate to motor vehicle traffic, structures providing drive-through access, and approaches to structures. These secure areas also include road block situations such as border crossings and/or motor vehicle access areas. Unfortunately, in this era of increased terrorism and violence it is a desire to provide barriers in more locations and of sufficient strength and adaptability to deter and/or prevent numerous methods and means of unauthorized access. Commonly, bollards provide a physical barrier or deterrent to entry by a motor vehicle. However, bollard systems fail to provide a mechanism to prevent or deter the disabling of the bollard, for example by cutting, prior to an attempted impact breach. 
   SUMMARY 
   An example of a bollard, which is positioned in a structure having a grade level, includes an outer member having a first section extending above the grade level and an inner member rotatably positioned within the outer member. 
   Another example of a bollard, which is positioned in a structure having a grade level, includes an outer member having a first section extending above the grade level; an inner member having a filler material; and a connector operationally connecting the inner member and the outer member, wherein the inner member straddles the grade level and is rotatable relative to the outer member. 
   An example of a bollard, for installing into a structure with a portion of the bollard extending above ground level, includes an outer member and an inner member rotatably positioned within the outer member. 
   The foregoing has outlined some of the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features and aspects of the present invention will be best understood with reference to the following detailed description of a specific embodiment of the invention, when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a conceptual view of an example of a bollard of the present invention. 
   

   DETAILED DESCRIPTION 
   Refer now to the drawings wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views. 
     FIG. 1  is a conceptual view of an example of a bollard system of the present invention, generally denoted by the numeral  10 . System  10  includes a bollard  12  mounted into a structure such as the ground  14  having a surface or grade level “GL”. In the illustrated example, bollard  12  is secured in the ground by a subsurface support such as concrete. However, it should be recognized that bollard  12  may be driven into ground  14  or secured in various manners. 
   Bollard  12  is a double-walled structure that provides strength against impact and deterrence to tampering. Bollard  12  includes an outer tubular member  18  and an inner member  20 . Outer tubular  18  may be constructed of any material to resist deformation upon impact from a motor vehicle, such as without limitation a metal pipe. Tubular  18  may have a circular cross-section or another geometric cross-section and may be referred to as a housing. The term tubular is utilized herein to include elongated members having an open interior or cavity. Outer tubular  18  includes an upper section  22  positioned above grade and a lower portion that is positioned below grade. 
   Inner member  20  may be constructive of various materials and for purposes of the illustrated example is constructed of a metal pipe. In the illustrated example, inner member  20  is includes a filler  26 , which may provide reinforcement for bollard  12 . In the illustrated example reinforcement is provided by the concrete filler  26  and reinforcement bars  28 . 
   Inner member  20  is rotatably positioned within the interior  24  of outer member  18 , so as to rotate or spin relative to outer member  18 . Inner member  20  may be functionally connected to outer tubular  18  in various manners to allow for rotational movement of inner member  20  relative to outer tubular  18 . For example, inner member  20  may be rotatably positioned in the earth and then outer tubular may be placed over it. Inner member  20  is connected to outer tubular  18  by an operational connector  30 . Operational connector  30  is particularly adapted to deter destruction of bollard  12  by cutting. For example, if one were to attempt to cut through bollard  12  the process would be stopped or delayed by inner member  20  rotating upon contact of the cutting blade. 
   Various assemblies may be utilized as operational connector  30  to support and provide rotation of inner member  20  relative to outer tubular  18 , it is noted that inner member  20  may not be physically connected directly to tubular  18 . In the illustrated example, connector assembly  20  is a swivel type assembly including a support structure  32  carrying or serving as a swivel  34  and a link  36  interconnecting structure  23  and inner member  20 . 
   In the illustrated example support structure  32  is as a cap, however it may be another type member such as a bar connected across tubular  18 . Support structure  32  may further be positioned above or below inner member  20 . Connecting link  36 , such as a metal shaft, chain or other linking member, is connected via swivel  34  between cap  32  and inner member  20 . Swivel  34  may include various mechanical devices or rotating connections. Swivel  34  may be provided at one or more locations such as, the connection between link  36  and cap  32 , the connection between link  36  and inner member  20 , and within a position on link  36 . In the illustrated example link  36  is a chain connected to one of the reinforcing member  32 . In the illustrated example, the provision of a connector assembly  30  forming a connection from the top of bollard  12  through inner member  18  maintains the subassemblies in connection when a disabling action is being attempted. 
   In operation, bollard  12  is installed within ground  14  or other structure such that upper section  22  is positioned above grade. Inner member  20  is rotatably positioned within outer member  18  so as to straddle the grade, illustrated by above grade portion  20   a  and below grade portion  20   b . A stop  38  may be positioned below inner member  20  a distance “D” so as to maintain inner member  20  in an operational position if link  36  is parted. For example, if link  36  were cut, inner member  20  would rest atop stop  40  and still extend above grade GL. Without link  36  in operation, inner member  20  is swiveling connected to outer member  18  by stop  40 . In effect, stop  40  serves as swivel connection  34 . It should be noted that it may be desired for swivel assembly  34  to be positioned below the grade to further prevent tampering. 
   From the foregoing detailed description of specific embodiments of the invention, it should be apparent that bollard that is novel has been disclosed. Although specific embodiments of the invention have been disclosed herein in some detail, this has been done solely for the purposes of describing various features and aspects of the invention, and is not intended to be limiting with respect to the scope of the invention. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the disclosed embodiments without departing from the spirit and scope of the invention as defined by the appended claims which follow.

Summary:
A bollard, which is positioned in a structure having a grade level, includes an outer member having a first section extending above the grade level; an inner member having a filler material; and a connector operationally connecting the inner member and the outer member, wherein the inner member straddles the grade level and is rotatable relative to the outer member.