Abstract:
A collision attenuating system for a moving vehicle including an energy-absorbing airbag assembly dimensioned and configured for attenuating the impact between the moving vehicle and a pedestrian or an impacted vehicle located in or crossing the path of the moving vehicle as the pedestrian or impacted vehicle impacts against the airbag assembly, a mounting bracket dimensioned and configured for being affixed to the moving vehicle, an engagement bracket affixed to the airbag assembly and engagable with the mounting bracket, and a quick-release fastener for removably engaging the engagement bracket to the mounting bracket for removably mounting the airbag assembly to the moving vehicle. The airbag assembly includes an airbag and an assembly frame supporting the airbag, a speed sensor for determining the speed of the vehicle, and a pressure regulator for controlling a pressure function of the airbag responsive to the speed sensor. The airbag assembly includes an upper deflatable airbag, and a lower pedestrian support, the pedestrian support including energy-absorbing structure. A method of using the collision attenuating system is also described.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. patent application Ser. No. 10/261,923, filed Oct. 1, 2002, entitled COLLISION ATTENUATOR ASSEMBLY and now U.S. Pat. No. 6,619,491, which is a Divisional of U.S. patent application Ser. No. 09/753,540 filed Jan. 2, 2001, entitled COLLISION ATTENUATOR ASSEMBLY and now U.S. Pat. No. 6,474,489, which is a Continuation-in-Part of U.S. Pat. No. 09/267,028, filed Mar. 12, 1999, entitled COLLISION ATTENUATOR ASSEMBLY and now abandoned, the entire contents of which applications is incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to collision attenuating systems and, more particularly, to improved collision attenuating systems for the front ends of railroad trains and other relatively large moving vehicles, and to methods for their use. 
     2. Description of Related Art 
     Railroad trains are heavy vehicles that are difficult to stop in emergency situations. Furthermore, railroad trains cannot be steered to avoid pedestrians and other motor vehicles that inadvertently cross the path of a moving railroad train. Railroad trains are extremely heavy relative to pedestrians as well as most motor vehicles including automobiles, sport-utility vehicles, trucks, vans, and buses. The front of a locomotive or a railroad car is typically constructed of a large rigid steel structure that yields minimally, if at all, in the event of a collision with a pedestrian or a motor vehicle. Unfortunately, due to these factors, collisions between railroad trains and pedestrians or between railroad trains and motor vehicles result all too often in fatalities for the pedestrians or for the occupants of the impacted motor vehicles. 
     Current efforts to reduce such fatalities have focused on collision prevention. Collision prevention techniques include warning devices on the railroad train such as horns and lights, warnings and barriers at railway and pedestrian crossings and as well as railway and motor vehicle crossings. Also, fencing is used along railroad right of ways to restrict access by pedestrians and/or motor vehicles. Unfortunately, pedestrians and motor vehicle operators on occasion accidentally miss, ignore, or deliberately circumvent these warning systems. 
     One known system for reducing the severity of impact between a train and a land vehicle is disclosed U.S. Pat. No. 6,293,205 to Butler. The Butler patent discloses a train collision system in the form of a flatbed car coupled to the front of a train. Disadvantageously, such systems are large and relatively expensive in that an additional railcar is required. Such systems are difficult to store and would occupy space that could be used by other working railcars and locomotives. Such systems may also be very expensive to maintain, replace or recondition, possibly approaching or exceeding the cost of a railcar. Furthermore, such systems are simply ineffective for collisions involving pedestrians. 
     What is needed is an improved collision attenuating system that overcomes the above and other disadvantages of known collision attenuating devices and collision prevention techniques. 
     Additionally, when a relatively large moving vehicle, such as a sport-utility vehicle, truck, or bus, impacts a pedestrian or a smaller vehicle, the difference in mass of the two results in an inordinate amount of damage and injury to the pedestrian or occupants of the smaller impacted vehicle. 
     What is also needed is an improved collision attenuating system that can be utilized on larger moving vehicles while overcoming the above and other disadvantages of known collision attenuating devices and collision prevention techniques. 
     BRIEF SUMMARY OF THE INVENTION 
     In summary, one aspect of the present invention is directed to a collision attenuating system for a moving vehicle including an energy-absorbing airbag assembly dimensioned and configured for attenuating the impact between the moving vehicle and a pedestrian or an impacted vehicle located in or crossing the path of the moving vehicle as the pedestrian or impacted vehicle impacts against the airbag assembly, a mounting bracket dimensioned and configured for being affixed to the moving vehicle, an engagement bracket affixed to the airbag assembly and engagable with the mounting bracket, and a quick-release fastener for removably engaging the engagement bracket to the mounting bracket for removably mounting the airbag assembly to the moving vehicle. In one embodiment, the collision attenuating system is mounted to a leading end of a leading railcar supported on a railway. 
     The airbag assembly may include an airbag and an assembly frame supporting the airbag, the engagement bracket being affixed to the assembly frame. The collision attenuating system may include a plurality of mounting brackets, a plurality of engagement brackets affixed to the assembly frame, and a plurality of quick-release fasteners for releasably engaging respective ones of the mounting and engagement brackets. The collision attenuating system may include a retractable wheel assembly mounted on the assembly frame for selectively raising the airbag assembly. The collision attenuating system may include a lifting mechanism mounting the retractable wheel assembly to the assembly frame. The collision attenuating system may include an energy-absorbing crush structure interconnecting the assembly frame and the engagement bracket. The collision attenuating system may include a shock absorber interconnecting the assembly frame and the engagement bracket. 
     In one embodiment, the collision attenuating system includes a speed sensor for determining the speed of the vehicle and a pressure regulator for controlling a pressure function of the airbag responsive to the speed sensor. The pressure regulator is an air pressure release valve. 
     Another aspect of the present invention is directed to a collision attenuating system for a moving vehicle including an energy-absorbing airbag assembly dimensioned and configured for attenuating the impact between the moving vehicle and a pedestrian or an impacted vehicle located in or crossing the path of the moving vehicle as the pedestrian or impacted vehicle impacts against the airbag assembly, the airbag assembly including an airbag and an assembly frame supporting the airbag, a speed sensor for determining the speed of the vehicle, and a pressure regulator for controlling a pressure function of the airbag responsive to the speed sensor. In one embodiment, the pressure regulator may include an air pressure release valve. Alternatively, the air pressure regulator may include a variable speed inflation fan. The attenuating system may include a mounting bracket dimensioned and configured for being affixed to the moving vehicle, an engagement bracket affixed to the airbag assembly and engagable with the mounting bracket, and a quick-release fastener for removably engaging the engagement bracket to the mounting bracket for removably mounting the airbag assembly to the moving vehicle. 
     Yet another aspect of the present invention is directed to a collision attenuating system including an energy-absorbing assembly dimensioned and configured for attenuating the impact between the moving vehicle and a pedestrian or an impacted vehicle located in or crossing the path of the moving vehicle as the pedestrian or impacted vehicle impacts against the energy-absorbing assembly, and an assembly frame for securing the energy-absorbing assembly to the moving vehicle, wherein the airbag assembly may include an upper deflatable airbag, and a lower pedestrian support, the pedestrian support including energy-absorbing structure. The upper deflatable airbag may include at least one internal baffle. The pedestrian support may include a hydraulic shock absorber and/or a pneumatic shock absorber. The pedestrian support may include an energy-absorbing crush structure. The collision attenuating system may include a skid plate located below the pedestrian support. In one embodiment, the energy-absorbing structure is constructed of foam, an air bladder, or a combination thereof. 
     In one embodiment, the pedestrian support is flexibly supported by the assembly frame such that a leading edge of the pedestrian support moves upward upon at least partial deflation of the upper deflatable airbag due to impact with the pedestrian or impacted vehicle. The collision attenuating system may include a hinge flexibly supporting the pedestrian support on the assembly frame. The collision attenuating system may include a locking retractor configured to prevent downward motion of the leading edge of the pedestrian support. The collision attenuating system may include a speed sensor for determining the speed of the vehicle, and a pressure regulator for controlling a pressure function of the airbag responsive to the speed sensor. In one embodiment, the pressure regulator is an air pressure release valve. The collision attenuating system may include a retractor interlock, wherein the retractor interlock locks the locking retractor once the release valve releases air from the upper deflatable airbag. The collision attenuating system may include a release mechanism for lowering the pedestrian support after the locking retractor is locked. The collision attenuating system may include, a mounting bracket dimensioned and configured for being affixed to the moving vehicle, an engagement bracket affixed to the airbag assembly and engagable with the mounting bracket, and a quick-release fastener for removably engaging the engagement bracket to the mounting bracket for removably mounting the airbag assembly to the moving vehicle. 
     An object of the present invention is to provide an improved collision attenuating system to better reduce the severity of an impact, which cannot be otherwise prevented, between a moving train or other relatively large vehicle and either a pedestrian or another relatively small vehicle. 
     Another object of the present invention is to provide a collision attenuating system configured to capture an impacted pedestrian. 
     The collision attenuating system of the present invention has other features and advantages that will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated in and form a part of this specification, and the following Detailed Description of the Invention, which together serve to explain the principles of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a collision attenuating system having an energy-absorbing unit and an assembly frame in accordance with the present invention, the collision attenuating system being shown mounted on a locomotive. 
     FIG. 2 is a side elevational view of the collision attenuating system of FIG. 1, the collision attenuating system shown removed from the locomotive. 
     FIG. 3 is a rear elevational view of the collision attenuating system of FIG.  1 . 
     FIG. 4 is a rear elevational view of a modified collision attenuating system assembly similar to that of FIG.  1 . 
     FIG. 5 is an enlarged perspective view of a quick-release bracket assembly of the collision attenuating system of FIG.  1 . 
     FIG. 6 is a side elevational view of the collision attenuating system of FIG. 1, shown equipped with a shock-absorbing unit mounted on the assembly frame. 
     FIG. 7 is a cross-sectional side view of the collision attenuating system of FIG. 1 showing details of a lower pedestrian support. 
     FIG. 8 is a side elevational view of the collision attenuating system of FIG. 1 shown in a folded storage mode. 
     FIG. 9 is a cross-sectional side view of the collision attenuating system of FIG. 1 shown following an impact with a pedestrian. 
     FIG. 10 is an enlarged detailed view of a locking retractor utilized by the collision attenuating system of FIG.  1 . 
     FIG. 11 is a partially fragmented perspective view of an airbag utilized by the collision attenuating system of FIG.  1 . 
     FIG. 12 is a partially fragmented perspective view of a modified collision attenuating system, similar to that shown in FIG. 1, showing details of a lower pedestrian support. 
     FIG. 13 is a schematic view of an airbag quick-lowering mechanism utilized by the collision attenuating system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Turning now to the drawings, wherein like components are designated by like reference numerals throughout the various figures, attention is directed to FIG. 1, which shows a collision attenuating system, generally designated by the numeral  30 , mounted on the front end of a locomotive  32 , which locomotive is equipped with a coupler and is configured for motion along a railway  33 . It will be understood that the collision attenuating system can also be configured for mounting on other types of railcars including, but not limited to, flatbeds, boxcars, and light rail vehicles. Alternatively, the collision attenuating system of the present invention may be configured for mounting on the front of relatively large and fast moving vehicles including, but not limited to, trucks, buses, automobiles, and/or sport-utility vehicles. 
     Collision attenuating system  30  generally includes an energy-absorbing airbag assembly  36  and an assembly frame  37  for supporting the airbag assembly and mounting it to the front end of locomotive  32 . In this respect, collision attenuating system  30  is similar in some aspects to the attenuators disclosed by U.S. Pat. No. 6,474,489, the entire content of which patent is incorporated herein by this reference. Collision attenuating system  30  of the present invention includes a variety of additional features including, but not limited to, a quick-release mounting system, a speed dependent pressure regulator, and an energy-absorbing pedestrian support, which features are discussed in greater detail below. 
     With continued reference to FIG. 1, energy-absorbing airbag assembly  36  includes an upper deflatable airbag  40  and a lower pedestrian support  41 , both of which are supported by assembly frame  37 . The assembly frame includes sixteen extension members  42  which position collision attenuating system  30  such that airbag assembly  36  is located in front of locomotive  32  a sufficient distance to clear the front coupler of locomotive  32 . 
     As shown in FIG.  2  and FIG. 3, assembly frame  37  is provided with a retractable wheel assembly  44  that may be used to install and/or uninstall collision attenuating system  30  on or from the front of locomotive  32 . Retractable wheel assembly  44  includes four wheels  45  mounted on a pair of wheel support frames  46 . In the illustrated embodiment, four caster wheels are mounted on two wheel support frames  46  in order to provide a stable, wheeled support for collision attenuating system  30  that may be wheeled in any direction. One should appreciate, however, that a number of different configurations may be used in accordance with the present invention. For example, one, two, three or more wheels can be utilized and may be mounted on one, two, three or more wheel frames. 
     Each wheel support frame  46  is retractably supported on a lower portion of assembly frame  37  by a lifting mechanism  49 . In the embodiment of FIG. 3, the lifting mechanism is in the form of a scissor jack. In one embodiment, scissor jacks  49  are activated by a lifting motor  50  that is operably coupled to the scissor jacks by a lifting screw  51 . Lifting motor  50  is actuated to spin lifting screw  51  either clockwise or counterclockwise in order to actuate scissor jacks  49  thus raising or lowering wheels  45  relative to assembly frame  37 . 
     The configuration of retractable wheel assembly  44  allows collision attenuating system  30  to be wheeled in front of locomotive  32  such that the collision attenuating system can be raised, aligned, and mounted on the front end of the locomotive. Once collision attenuating system  30  is engaged to the front of locomotive  32 , the lifting mechanism can again be activated in order to raise retractable wheel assembly  44  with respect to assembly frame  37  thus providing clearance between collision attenuating system  30  and railway  33 . 
     One should appreciate that the configuration of the retractable wheel assembly and the lifting mechanism may vary in accordance with the present invention and can include hydraulic, pneumatic, mechanical and/or electrical lifting means. For example, FIG. 4 shows an alternative lifting mechanism  49   a  on the base of assembly frame  37   a . In this embodiment, lifting mechanism  49   a  is in the form of a lever  54  and lifting linkage assembly  56  that pivots wheel support frames  46   a  such that wheels  45   a  are raised and lowered with respect to assembly frame  37   a . A shown in FIG. 4, when lever  54  is in its leftmost position, wheels  35   a  are rotated upward in a retracted position. This is the normal operating position of wheels  35   a  when collision attenuating system  30  is attached to the front of locomotive  32 . 
     Referring to FIG. 5, mounting brackets  59  may be permanently mounted on locomotive  32 . Collision attenuating system  30  can be quickly attached to locomotive  32  by rolling the collision attenuating system into position in front of the locomotive, aligning the engagement brackets above the mounting brackets, and the actuating lifting mechanism to lower the collision attenuating system such that the engagement brackets slide into mounting brackets. The engagement and mounting brackets have a quick-release configuration such that collision attenuating system  30  can be quickly installed and removed from locomotive  32 . 
     In the illustrated embodiment, engagement bracket  58  includes a tapered protrusion  60  that is received in a correspondingly shaped receptacle  61  of mounting bracket  59 . Projection  60  and receptacle  61  include aligned engagement bores  64  and  65 , respectively, through which a safety pin  66  is inserted to releasably secure engagement bracket  58  and mounting bracket  59 , thus releasably securing collision attenuating system  30  to the front of locomotive  32 . In the illustrated embodiment, the engagement pin is a tapered pin having a cotter pin to prevent the engagement pin from inadvertently sliding out of the engagement bores. One should appreciate that other fastening means including, but not limited to, wing nuts, spring pins, spring latches, and other well known means can be utilized in accordance with the present invention. 
     When collision attenuating system  30  is to be removed, the quick-release brackets are disengaged, that is, safety pin  66  is removed from engagement bores  64  and  65 , then lifting mechanism  49  is actuated to first lower wheels  45  to the ground. Continued actuation of lifting mechanism  49  raises collision attenuating system  30  and engagement bracket  58  relative to locomotive  32  and mounting bracket  59  and thus lifts engagement bracket  58  out from mounting bracket  59 . Once engagement brackets  58  are clear of mounting brackets  59 , collision attenuating system  30  may be rolled away from locomotive  32  on wheels  43 . 
     Turning now to the airbag assembly, in the event that locomotive  31  collides with a pedestrian in or crossing railway  33  in the path of the locomotive, the pedestrian will impact airbag assembly  36  and cause upper deflatable airbag  40  to deflate and absorb a substantial amount of the impact force. The shock-absorbing configuration of the airbag assembly allows the stricken pedestrian to accelerate to the speed of locomotive  32  and fall onto a pedestrian support  41  as deflatable airbag  40  collapses. As the stricken pedestrian is carried along by pedestrian support  41 , the likelihood of the stricken pedestrian falling under the moving locomotive is decreased. 
     In one embodiment, deflatable airbag  40  is constructed of a flexible material such as, but not limited to, 22 oz vinyl coated polyester and/or other suitable fabrics. Preferably, deflatable airbag  40  is continuously inflated by an inflation fan  68 , shown in FIG. 3, while locomotive  32  is traveling along railway  33 . One should appreciate that the deflatable airbag may be configured to be selectively inflatable in accordance with the present invention. For example, an activation control switch may be provided in the locomotive operator&#39;s compartment such that the inflation fan is activated as determined necessary by the locomotive operator. Alternatively, the inflation fan may be configured such that it is actuated once the locomotive reaches a predetermined minimum speed. Alternatively, the deflatable airbag may be inflated by other suitable means. For example, an air supply in the form of the conventional compressed air supply available on a railway locomotive that is commonly used for pressurizing the brake system may be utilized to inflate the deflatable airbag. 
     Preferably, inflation fan  68  is a variable speed fan that pressurizes deflatable airbag  40  proportional to the speed of locomotive. In the illustrated embodiment, the speed of inflation fan  68  is controlled by a signal output by a locomotive speed sensor  69 , which sensor is shown in FIG.  1 . The signal from speed sensor  69  can be an analog voltage or a digitally encoded signal. As locomotive  31  accelerates, the speed signal increases in value and inflation fan  68  runs faster, thus increasing the air pressure within deflatable airbag  40 . In low speed collisions, the air pressure is relatively low providing a lower resisting force, that is, a lower amount of energy absorption of the deflatable airbag that, in turn, will provide a less abrupt acceleration of the impacted pedestrian and a better chance of pedestrian capture. In higher speed collisions, the resisting force is higher allowing deflatable airbag  40  to absorb the higher levels of energy present in such higher speed collisions. The increased air pressure within deflatable airbag  40  at higher speeds also will keep the airbag shape from distorting under the higher air resistance encountered at higher locomotive speeds. 
     As shown in FIG. 3, deflatable airbag  40  is provided with a pressure regulator in the form of a relief valve, or as illustrated, in the form of three pressure relief doors  70  located on a rear surface of the deflatable airbag. Alternatively, the pressure relief doors may be located on the top and/or sides of the deflatable airbag. Pressure relief doors  70  may be formed of rigid or semi-rigid panels that are hinged and in fluid communication with the deflatable airbag. Alternatively, the pressure relief doors may be fabric panels. Although the illustrated embodiment includes three pressure relief doors, one should appreciate that one, two, three or more pressure relief doors may be utilized in accordance with the present invention. 
     Pressure relief doors  70  are secured closed by respective pressure relief latches  71 . In one embodiment, latches  71  are not only sensitive to the pressure within deflatable airbag  40  but are also sensitive to the speed signal from speed sensor  69 . In particular, a trigger threshold, that is, the minimum pressure at which latches  71  will allow doors  70  to open is a function of train speed. In low speed collisions, the trigger threshold is low allowing the deflatable airbag  40  to quickly collapse on impact. The low trigger threshold increases the probability that the pedestrian will be successfully captured by the energy-absorbing assembly and carried upon pedestrian support  41 . At higher train speeds, the trigger threshold is higher thus reducing the possibility of accidental release of the air pressure in deflatable airbag  40 , for example, in response to increased pressure within the deflatable airbag is response to the increased force of air resistance encountered at higher locomotive speeds. 
     In the embodiment illustrated in FIG.  2  and FIG. 3, pedestrian support  41  is constructed with a thick layer of foam encased in flexible material such as, but not limited to, 22 oz vinyl coated polyester and/or other suitable fabrics. Preferably, the foam layer of the pedestrian support is approximately six inches thick, however, one will appreciate that the actual dimensions of the pedestrian support may vary. 
     In other embodiments, the pedestrian support structure may include other suitable energy-absorbing means that has sufficient structural integrity to support a stricken pedestrian thereon. For example, pedestrian support may be constructed of an air filled rubber bladder and/or semi-rigid or even rigid structures. Examples of possible rigid or semi-rigid structures include, but are not limited to, corrugated cardboard, plastic, rubber, plastic plates, plywood structures, and frames with netting. 
     In the event that collision attenuating system  30  collides with a moving vehicle, airbag assembly  36  will quickly collapse and might not significantly reduce the acceleration forces on the moving vehicle due to the substantially greater weight of the moving vehicle relative to a pedestrian. To further adapt collision attenuating system  30  for impacts with moving vehicles, airbag assembly frame  37  may be provided with mounting shock absorbers  74  interconnecting extension members  42  and engagement brackets  58 , as shown in FIG.  6 . In this case, shock absorbers  74  will compress and absorb the increased force of impact when locomotive  32  impacts a moving vehicle. Shock absorbers  74  are dimensioned and configured to absorb the greater impact energy due to a locomotive/moving vehicle collision. In the illustrated embodiment, shock absorbers  74  are either hydraulic or pneumatic cylinders. One will appreciate that other shock-absorbing means can be utilized in accordance with the present invention including, but not limited to, a crush structure, a collapsing structure utilizing interlocking channels with sheer pins, and/or other suitable means. 
     Turning now to FIG. 7, pedestrian support  41  is pivotally connected to a lower portion of assembly frame  37  by a hinged connection  76 . The hinged configuration allows a deflated collision attenuating system to be folded up for easier maneuvering on wheels  45 , as shown in FIG.  8 . This hinged configuration increases the operational ease of collision attenuating system  30  and of installing the system on locomotive  32  and/or other relatively large vehicles. 
     With continued reference to FIG. 7, the illustrated collision attenuating system  30  is provided with a retracting mechanism  77 , however, one will appreciate that a retracting mechanism need not be used. In this embodiment, a plurality of retraction cords  78  are attached at one end to a forward portion of pedestrian support  41 . Each retraction cord  78  extends through a ratcheting pulley  83 . Any suitable ratcheting pulley means can be utilized in accordance with the present invention including, but not limited to the ROPE RATCHET® tie-down, manufactured by Carolina North Manufacturing, Inc. of Kernersville, N.C. The opposite end of each retraction cord  78  is attached to a spring mechanism  84  that, in turn, is secured to assembly frame  37  by an anchor connection  85 . One will appreciate that any suitable spring means can be utilized including, but not limited to, a spring, an elastic cord and/or other suitable biasing means. 
     When ratcheting pulley  83  is in a first ratchet mode, the retraction cords may travel through the pulleys in one direction but not the other. For example, as pedestrian support  41  pivots counterclockwise about hinged connection  76 , spring mechanism  84  draws retraction cord  78  through ratcheting pulley  83  in one direction. Ratcheting pulley  83  prevents pedestrian support from pivoting in a clockwise direction because ratcheting pulley  83  prevents withdrawal of retraction cord  78  in the opposite direction. 
     FIG. 9 is a cutaway view of collision attenuating system  30  showing a stricken pedestrian  87  following impact. The force of impact causes the stricken pedestrian to deflect or otherwise bias retraction cord  78  as deflatable airbag  40  collapses. The deflection of retraction cord  78  pulls the forward end of pedestrian support  41  upward. Inertial and other forces, in turn, cause pedestrian support  41  to continue to rotate upward and counterclockwise about hinged connection  76  and create slack in retraction cord  78 . Spring mechanism  84  pulls the slack from retraction cord  78  through ratcheting pulley  83 . Meanwhile, ratcheting pulley  83  locks retraction cord  78  in place thus holding the forward end of pedestrian support  41  in a raised position, as shown in FIG.  9 . The pivoting and locking configuration reduces the possibility that pedestrian  87  will slide or otherwise fall off pedestrian support  41  after impact collision and before the train reaches a complete stop. 
     In one embodiment shown in FIG. 10, ratcheting pulley  83  may include a ratchet control lever  90  having a deactivated position and an operational position. In the deactivated position, retraction cord  78  moves freely in either direction. In the operational position, retraction cord  78  may only move in a single direction. Ratchet control lever  90  is spring loaded, and when unloaded returns to the operational or ratchet mode in which retraction cord  78  may only move in a single direction. Ratchet control lever  90  is held in the deactivated position by an interlock wire  91 . Interlock wire  91  may be interconnected with one or more of the pressure relief doors  70  or other suitable pressure relief valve. 
     During normal operation ratchet control lever  90  is in the deactivated or free position so that retraction cord  78  is free to move through retraction pulley  83  in either direction. Thus airbag assembly  36  can be easily and repeatedly folded up, as shown in FIG. 8, and down, as shown in FIG.  2 . Upon impact, air pressure release door  70  opens and pulls interlock wire  91  away from retraction pulley  83  and thus releases ratchet control lever  90 . The spring loaded ratchet control lever  90  will move to the activated position thus allowing retraction cord  78  to move through ratcheting pulley  83  in a counterclockwise direction, as illustrated in FIG.  9 . Accordingly, when retraction mechanism  77  is activated, pedestrian support  41  may only pivot upwardly thus facilitating the capture of a stricken pedestrian. 
     Collision attenuating system  30  may include other features. For example, FIG. 11 schematically illustrates a plurality of internal baffles  94  within deflatable airbag  40 . In the illustrated embodiment, four vertical baffles  94  are attached to the top, the front sloping surface, and the bottom. One will appreciate, however, that one or more vertical, horizontal, and/or diagonal baffles may be attached to the top, the sides, and/or the bottom of the deflatable airbag. The internal baffles maintain the preferred shape of the inflatable airbag. Preferably, the internal baffles are constructed from the same fabric as the exterior of the deflatable airbag including, but not limited to, 22 oz reinforced vinyl fabric. Alternatively, other fabrics, mesh netting, or even a set of cords may be used to maintain the inflated shape of the deflatable airbag. A plurality of horizontal cords  95  are also shown in FIG. 11 that may be provided to maintain the shape of the airbag. Each horizontal cord  95  connects one or more adjacent internal baffles  94  together and/or to the side of deflatable airbag  40 . Horizontal cords  95  prevent the sides of the deflatable airbag from bellowing outward and/or protruding sideways. Preferably, horizontal cords  95  are attached to tabs having grommets, which tabs are sewn to the sides of deflatable airbag  40  and/or the side of internal baffles  94 . One will appreciate, however, that the collision attenuating assembly of the present invention need not be provided with internal baffles and/or horizontal cords. 
     Turning now to FIG. 12, which illustrates another embodiment of airbag assembly  36 , pedestrian support  41  may include one or more energy-absorbing units  98  interconnecting hinge  80  and a flexible leading edge  99 . In the illustrated embodiment, the energy-absorbing units are provided in the form of shock absorbers, however, one will appreciate that other suitable energy-absorbing means may be used. Energy-absorbing units  98  can be hydraulic cylinders, pneumatic cylinders and/or other suitable energy-absorbing means including, but not limited to, crush structures and/or collapsing structures such as those utilizing interlocking channels with sheer pins. When airbag assembly  36  collides with a pedestrian, leading edge  99  contacts the lower extremities of the pedestrian. Shock absorbers  98  absorb some of the energy from the collision reducing the severity of the impact on the pedestrian. Although pedestrian support  41  partially collapses, it retains enough of its shape to support the pedestrian after impact. 
     FIG. 13 shows a further feature that may be utilized with the above-mentioned embodiments including, but not limited to, collision attenuating system  30 . Airbag assembly  36  is provided with a one or more diagonal release cords  102 . One end of release cord is attached to and supports the leading edge of airbag assembly  36  in the manner shown in FIG.  13 . The opposite end, that is, the top rear end of each release cord  102  is attached to a release bracket  103 . When the airbag is deployed under normal operation, the diagonal release cords hold the leading edge of the airbag up approximately 2-6 inches above railway  33 . This reduces the probability that the airbag will be damaged by contact with the railway  33 . When the operator of the train determines that there is a pedestrian in or about to cross the path of locomotive  30 , the operator may activate a release switch  106  in the locomotive that activates the releasable catch such that release brackets  103  are freed thus allowing pedestrian support  41  to pivot downwardly until release cords  102  become taut thereby preventing pedestrian support  41  from dropping any further. Alternatively, one or more skid plates  107  may be provided to contact and slide along railway  33  thus positioning the pedestrian support. Preferably, skid plates  107  are made from strong material such as TEFLON®, plastic, metal, fiberglass, or wood. The lowered airbag increases the likelihood that the pedestrian will be captured by the airbag. This is especially useful when the pedestrian in a seated or prone position. 
     For convenience in explanation and accurate definition in the appended claims, the terms “up” or “upper”, “down” or “lower”, “inside” and “outside” are used to describe features of the present invention with reference to the positions of such features as displayed in the figures. 
     In many respects the modifications of the various figures resemble those of preceding modifications and the same reference numerals followed by subscript “a” designate corresponding parts. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.