Patent Publication Number: US-6659682-B2

Title: Deformable speed hump

Description:
This is a continuation-in-part of U.S. patent application Ser. No. 09/180,621, filed Jan. 8, 1999, which was the National Stage of International Application Ser. No. PCT/GB98/00748, filed Mar. 12, 1998, which claims priority to Great Britain Application No. 9705078.5 filed Mar. 12, 1997. The present application is related to U.S. patent application Ser. No. 10/204,895, filed Aug. 26, 2002. 
    
    
     Speed humps or ‘Sleeping Policeman, ’ as they are better known, are well known deterrents for speeding motorists and are becoming more widely used through the traffic calming measures being imposed by local authorities. The present speed hump can be either an asphalt or block paviour mound, which are formed directly upon the existing road surface or as an alternative can be made from a solid compound such as plastic which again can be fitted to the road surface. 
     According to the authorities and surveys of public opinion it is essential to reduce the speed of motorist in general especially on inner city urban carriage ways. The present systems of speed control are costly and disruptive, with the tax payer and local businesses bearing the cost. Additionally the confusion caused to an already congested road network is totally unacceptable with journey times increasing and repairs to the roads never ending. 
     It is an object of the present invention to obviate or mitigate the above problems. According to the invention there is provided a road traffic speed control device which is locatable in a roadway, is formed of a resiliently deformable material and is deflatable by the passage of a vehicle thereover at the intend-e-d speed limit of said vehicle in said roadway, in use. 
     The device may be formed from an extruded or compressed partially recyclable rubber compound. 
     The device may be generally semi-cylindrical or sinusoidal in transverse cross-section and may be formed with perforations or apertures therein to permit deflation. 
     Alternatively or in addition, valve means may be located in a side wall of the device to allow deflation and reinflation, in use. 
     One or more helical springs, which may be encased in a split sleeve, may be located within the device to assist in shape retention. 
     The device may be formed with perforations, apertures or valve means to provide deflation thereof with passage thereover of a vehicle traveling from a minimum speed of 5 mph through increments to a required maximum. 
     The device may be formed such that subsequent to deflation by the front wheels of a vehicle passing thereover, reinflation may be delayed to allow the rear wheels to pass thereover during such initial deflation. 
    
    
     The foregoing and further features of the invention may be more readily understood from the following description of preferred embodiments thereof, by way of example with reference to the accompanying drawings in which: 
     FIG. 1 shows a schematic end sectional view of a road traffic speed control device and fixing therefore; 
     FIG. 2 shows a plan view of the device of FIG. 1; 
     FIGS. 2A and 2B show sectional views along the lines A—A and B—B respectively of FIG. 2; 
     FIG. 3 is a schematic sectional view of devices of FIGS. 1 and 2 located across a road; 
     FIG. 4 is a schematic perspective view of a device showing drainage to discharge surface water; 
     FIG. 5 is a schematic end sectional view of an alternative device including a two-way valve for controlling deflation and reinflation, in use; 
     FIG. 6 is a perspective view from above of a further alternative embodiment; 
     FIG. 7 is a schematic side sectional view of the embodiment of FIG. 6; and 
     FIG. 8 shows a perspective view of a further embodiment of the invention. 
    
    
     Referring now to the drawings a road traffic speed control device D is preferably formed from an extruded or compressed recyclable rubber compound. The shape represents a semi-cylindrical, sectional shape in construction with a series of apertures  3  formed through the profiled casing, which allows the circulation of air under controlled circumstances to be released, thus deflating the device D into a level plane giving a smooth passage to a vehicle passing thereover. 
     To assist in the shape retention a helical spring  4  encased in a suitable split sleeve  5  is installed at the center of the device D. To secure the unit a spreader plate or washer  6  is inserted at the base of the protective shroud during the curing procedure to help relieve the impact force when in operation. Also to assist in the distribution of the impact forces, the device D is tapered into a fillet  7  at each end of the base line thereof. 
     The device D is preferably produced in 750 mm. sections accompanied by tailor made inserts  8  to complete a road crossing (determined during the on site survey). To assist in the equal spacing of the device D a 50 mm spacer  9  is molded onto the end of the unit which is interlocked at  10  to provide an overall 05 mm. expansion gap giving added rigidity to the whole structure. 
     The device D is attached to a road surface by bolts  2  engaging into anchoring devices  1  located in the road surface. 
     The idea profile is 750 mm in width and 100 mm in height. This is uniform throughout the entire structure which enables vehicle manufacturers to work to a stated height restriction from the top of the hump to the underside of the vehicle similar to the restriction placed on high sided vehicles. Should damage occur, the section in question can be simply unbolted and replaced by a standard length of device causing minimal disruption and with no road excavation taking place. 
     The number and size of apertures  3  is determined to allow the device D to be deflated by the front wheels of a vehicle passing thereover, providing the vehicle is not exceeding a predetermined speed. 
     Should the vehicle be traveling at a speed exceeding the predetermined maximum; the device does not deflate and acts substantially as a rigid hump. 
     FIG. 3 shows a device D with drainage apertures  12  covered with mesh to prevent the ingress of leaves or other debris into device D. 
     FIG. 5 shows an alternative device D having a two-way valve  13  provided to control deflation and reinflation and may be adjustable to control maximum speed at which deflation does not occur. Such valve  13  may be provided in addition to apertures  3  or as on alternative thereto. 
     FIGS. 6 and 7 show a further alternative embodiment in which the cross section of the device is generally sinusoidal so as to provide a relatively smooth passage over a solid run up portion  14  of the device prior to a vehicle traversing the deflatable portion D. 
     A further embodiment of the invention is shown in FIG.  8 . This has an outer, vehicle bearing wall and an inner tube  16  located inside the cavity of the device D, mounted transversely in relation to the roadway. The valve means  13  are connected directly to the inner tube  16 . As with other embodiments, the air passes freely to the atmosphere under the dictates of the valve  13  but now the inner tube provides a more predictable air volume. This therefore allows better control of the speed response of the device. The inner tube  16  is made resilient such that after passage of the vehicle, the inner tube retains its shape, therefore refilling with air through the valve  13 . The outer wall  15  of the device may itself be resilient or may re-assume its shape due to the resilience of the inner tube. Consequently a more predictable operation of the valve  13  is obtained. The part of the cavity outside the hose may be sealed or open to the atmosphere without restriction.