Patent Publication Number: US-11028602-B2

Title: Suspended scaffolding system

Description:
FIELD OF THE INVENTION 
     This invention relates to a scaffolding system. Particularly, but not exclusively, the invention relates to a suspended scaffolding system, for example of the type for use in the construction, inspection and maintenance of structures, in particular spanning structures. 
     Although reference has been made to spanning structures, it is understood that the invention may be used in the construction, inspection and maintenance of many other different types of structures such as: buildings, tunnels, elevated roadways, walkways, aqueducts, and other similar civil engineering undertakings. 
     BACKGROUND OF THE INVENTION 
     Many different structures span across a distance of for example, ten or more metres, including bridges and viaducts. These structures require temporary access from beneath during construction, inspection and maintenance routines, however access can be difficult. One method of access is to build a temporary scaffold from the ground up but this is unfeasible in many circumstances. Another method is to build a walkway or gantry whilst the structure is being built, however this increases costs at that stage, requires foresight and also may require security to prevent unauthorised access of the gantry. 
     It has therefore been recognised for a long time that a temporary structure, that is cheap and easy to deploy; is adaptable to a variety of different locations and situations; and which is safe and easy to use is wanted for construction, inspection and maintenance. 
     PRIOR ART 
     U.S. Pat. No. 4,154,318 and French Patent 2845715 disclose the use of a mobile suspended scaffold which is mounted onto a vehicle. The vehicle is driven along a bridge enabling work or inspection. if there are obstacles along the edge of the bridge the whole scaffold must be retracted and repositioned making it awkward to use in some circumstances. Some existing scaffolding systems are a suspended type ones (PER! type), but they have supporting and stabilizing elements as beams, frames or portal frames mounted on the upper surface of the structure/bridge resulting in blocking or restricting of this space use for other purposes whilst the scaffolding is present. 
     An object of the invention is to overcome problems associated with aforementioned construction, inspection and maintenance systems by providing a single system that is suitable for a variety of different structures, which is physically able to be re-arranged to suit different applications and that is simple and cheap to use and is readily deployed and most importantly safe. No prior art arrangements achieve simple and effective stabilization of the suspended object in relation to the solid structure by the method described in this invention. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a suspended scaffolding system which includes a connector system adapted to engage a fixture, the fixture in use is in contact with a surface of a structure, an arm connects the suspended scaffolding system to the connector system, so that in use the suspended scaffolding system is suspended below the structure, characterised in that, the connector system has connectors that permit relative movement with respect to the fixture in two orthogonal planes. 
     Preferably, relative movement is permitted with respect to the fixture in three orthogonal planes. 
     Thus, according to this aspect of the invention, the scaffolding system is able to move laterally (from side to side). This lateral motion is achieved by way of the connector. Preferably, the connector comprises a spherical device supported within a tubular device, but other solutions, for example as Cardan mount, can be used. In a preferred embodiment, the connector includes a spherical bearing. The connector may comprise a universal connector. Alternatively, the connector includes a ball and socket device. 
     It is preferred that the fixture comprises a track along which the scaffolding system can run. This enables the scaffolding system to move both laterally (from side to side) and forwards and backwards. 
     Rapid, safe and easy motion of the scaffolding system, lengthwise along the bridge or structure, is important as the quicker and easier it is able to transport equipment and personnel to a desired location the better this is. However, when reaching a specific position, it is important that the suspended scaffolding system is able to be placed into a relatively stable and stationary state so that crew using it can work on the structure safely and without undue movement in the suspended scaffolding system. Prior art generally requires elaborate locking and the deployment of safety equipment so that this could occur. Deployment and retrieval of the locking and safety equipment took time and so reduced productivity. 
     According to a second aspect of the invention there is provided a suspended scaffolding system including a connector system adapted to engage a fixture, the fixture in use is in contact with a surface of a structure. an arm connects the suspended scaffolding system to the connector system so that in use the suspended scaffolding system is suspended below the structure, characterised in that at least one moveable counterweight is provided on the suspended scaffolding system, which is adapted to be displaced from a first position to a second position so as to change the centre of gravity of the suspended scaffolding system. 
     The invention provides an alternate manner of providing movable scaffolding for a structure by utilising a counterweight to stabilize a suspended movable scaffolding, having adaptable geometry, easily stabilized, lockable and equally easily releasable during the process of work carried out, able to overcome obstacles structurally present in the main structure without using large areas of the upper surface of the structure for mounting support elements. 
     The scaffolding is suspended from a fixture which preferably comprises a rail, either on the top of the main structure, its edge or underside. If the rail and a cooperating carriage system on the scaffolding system is used as the attachment, the working platform and the scaffolding can move as work progresses along the structure. 
     A further object of the invention is to provide a suspended scaffolding system having a support positioned on one or more of the upper, side and/or lower surface of a structure whereby a counterweight movable between two positions moves the suspended scaffolding system&#39;s centre of gravity thereby producing a pushing force for stabilizing the equipment in a working position against main firm structure or object (building, bridge, slab, terrace or diff, rock, cave, ship etc.). 
     Thus the movement of the counterweight changes the position of the centre of gravity of the system by producing an acting force that pushes the suspended scaffolding against the main stable structure and in that way stabilizes scaffolding position. 
     Preferably, a hydraulic jack powered by a motor is provided to displace the counterweight. Alternatively or additionally a hand crank is provided to displace the counterweight. Another system of displacing the counterweight can be introduced, electric or pneumatic jack for example, or even manually operated one such as a chain winch or pulley. The person skilled in the art will appreciate which alternative embodiments are suitable for use with the system. 
     According to a third aspect of the invention there is provided a suspended scaffolding system which includes a track connector system adapted to engage a track, the track in use is in contact with the surface of a structure, characterised in that the track connector system comprises at least three fasteners each of which is in contact with the track and each is adapted to be temporarily removed from the track, when encountering an obstacle, so as to permit the suspended scaffolding system to negotiate the obstacle or to move into a new position. 
     According to a fourth aspect is a method of moving a scaffolding system which is movable along a rail, the rail being fixed to a surface by at least one fastener comprising the steps of:
         providing a further fastener to fix the rail to a structure;   removing one of the at least one fasteners to enable the scaffolding system to progress its&#39; movement; and   optionally replacing the removed fastener once the scaffolding system has progressed its&#39; movement.       

     The fastener can be removed from the rail entirely or pivoted out of the way. This arrangement enables the scaffolding system to be used along the entire length of a structure, straight or curved, which is for example a bridge, on a rail, runner or section of a rail or runner. Sections of rail or runner may be removed and placed ahead of another section. 
     In a preferred embodiment, the suspended scaffolding system includes a suspended working platform (SWP™) and a safety rails disposed around a periphery of the working platform. 
     Traditionally, in this type of system, reaction bearings or end stops are used to prevent the scaffolding system overrunning and either becoming completely dislodged from the rail or causing damage to the connector of the scaffolding system. However, the fact that end stops are used means that these have to be removed when a new rail section is added which is time consuming and requires extra parts. 
     In the present invention, it is preferred that a rail end automated blocking device, designed within the rail itself, is used which are active if the rail segment is the end one, but which is de-activated by the connection on the next rail segment. This has the added safety advantage that a worker does not have to remember to add an end piece during construction; each rail has an end piece integral to it. 
     According to another aspect of the invention, there is provided a method of stabilizing a suspended structure comprising the steps of: providing a suspended structure; and adjusting the suspended structures&#39; centre of gravity away from a neutral position thereby producing a stabilizing force. 
     Preferably, the adjustment of the suspended structures&#39; centre of gravity is achieved by one or more of counterweight movement, ballasting and swinging. Example include moving a mass element (sliding, swinging, rotating, pumping ballast from tank to tank) or by adding or removing mass to/from the object (filling/emptying ballasting tanks). 
     In a preferred embodiment, the stabilizing force is transferred to a supporting structure using a bumper. 
     Preferably, there is provided one fixed suspension point located on the upper, side or lower edge/surface of the structure and at least two bumpers of the suspended object in contact with the structure, giving in total three points of stabilization of the suspended object position. 
     In a preferred embodiment, there are provided two fixed suspension points located on the upper, side or lower edge/surface of the structure and at least one bumper of the suspended object in contact with the structure, giving in total at least three points of stabilization of the suspended object position. 
     Adjusting the centre of gravity by deployment of for example a counterweight, the centre of gravity of the scaffolding system is shifted from a first location, at which the scaffolding system hangs freely on one or more fixing points and is able to move freely, for example by running along a rail, to a second location in which the scaffolding system is urged against the structure so that the scaffolding system is held in a relatively fixed position with at least two points in contact with a rail or runner and at least one, the third point in contact with the structure, which as a result of a reaction force ensure that the scaffolding system remains stationary, but which can be moved to a different location relatively quickly and easily, even by personnel who are on board a working platform supported by the scaffolding. 
     Preferably the third point of contact is by way of a friction pad or buffer/bumper. 
     Preferably, the suspended scaffolding system comprises a contact point, with the structure, includes a reaction bearing roller. 
     Therefore, it is an object of the invention to provide the technical stabilization method of the suspending objects/technical equipment in relation to the main stable outer structure by using the adjustable and lockable counterweight as part of the suspended object and by this counterweight intentional displacement inducting pushing/locking force stabilizing the suspended object to the main structure. 
     When using movable and adjustable counterweight and bumper/buffer system the SSS—Suspended Scaffolding System do not requires any additional top surface level or under surface level cooperation or support except own one. When the movable and adjustable counterweight is engaged it pushes the SWP—Suspended Working Platform towards the bridge/structure locking it into position. When the counterweight is disengaged, there is no pushing and no contact with the bridge/structure and the SWP can be easily moved/passed, to the new working area. 
     The SSS—Suspended Scaffolding System is more practical and cost-effective solution, than the currently used ones: top support mounted frames with suspended arms; trailer under bridge inspection units; lower level surface mounted up scaffolding for the structure above. The invention is presented here (as particular example, not excluding other different applications) as the mode to construct the suspended scaffolding with working platform (SWP) for carrying the maintenance or structural work from underneath the bridge/structure without using the constructing extended scaffolding structures on the top of the bridge as support for the mounted down scaffolding towers with suspended on the underside working platforms. The SSS solution saves time and money, as well leaving upper bridge/structure surface freely accessible for other stages of construction work or the standard uninterrupted and not distracted use. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described, by way of example, with reference to the accompanying drawings: in which:— 
         FIGS. 1A-1B  show a diagram of the technical stabilizing device ( FIG. 1A ) and main acting forces scheme ( FIG. 1B ) showing a suspended object in free hanging and moveable position, for the option of upper surface fixing to the main structure; 
         FIGS. 2A-2B  show a diagram of the technical stabilizing device ( FIG. 2A ) and main acting forces scheme ( FIG. 2B ) showing a suspended object in working position, for the option of upper surface fixing to the main structure; 
         FIGS. 3A-3B  show a diagram of the technical stabilizing device ( FIG. 3A ) and main acting forces scheme ( FIG. 3B ) showing a suspended object in free hanging and moveable position, for the option of underside surface fixing to the main structure; 
         FIGS. 4A-4B  show a diagram of the technical stabilizing device ( FIG. 4A ) and main acting forces scheme ( FIG. 4B ) showing a suspended object in working position, for the option of underside surface fixing to the main structure; 
         FIGS. 5A-5B  show a diagram of the technical stabilizing device ( FIG. 5A ) and main acting forces scheme ( FIG. 5B ) showing a suspended object in free hanging and moveable position, for the option of side surface fixing to the main structure; 
         FIGS. 6A-6B  show a diagram of the technical stabilizing device ( FIG. 6A ) and main acting forces scheme ( FIG. 6B ) showing a suspended object in working position, for the option of side surface fixing to the main structure; 
         FIGS. 7A-7B  show a diagram of the technical stabilizing device ( FIG. 7A ) and main acting forces scheme ( FIG. 7B ) showing a suspended object in free hanging and moveable position, for the option of slot upper surface fixing to the main structure; 
         FIGS. 8A-8B  show a diagram of the technical stabilizing device ( FIG. 8A ) and main acting forces scheme ( FIG. 8B ) showing a suspended object in working position, for the option of slot upper surface fixing to the main structure; 
         FIGS. 9A-9B  show a diagram of the technical stabilizing device ( FIG. 9A ) and main acting forces scheme ( FIG. 9B ) showing a suspended object in free hanging and moveable position, for the option of underside internal surface fixing to the main structure; 
         FIGS. 10A-10B  show a diagram of the technical stabilizing device ( FIG. 10A ) and main acting forces scheme ( FIG. 10B ) showing a suspended object in working position—stabilized according to the invention, for the option of underside internal surface fixing to the main structure; 
         FIG. 11  is a perspective of a frame (SWP— Suspended Working Platform) for a suspended scaffolding system according to the invention; 
         FIGS. 12A-12B  show a perspective of an attachment system for attaching a frame (SWP™—Suspended Working Platform) to a rail; 
         FIGS. 13A-13B  show a perspective of a counterweight system according to the invention; 
         FIG. 14  is a perspective of a counterweight system in free hanging position; 
         FIGS. 15A-15B  show a cross section through a rail and carriage truck; 
         FIG. 16  is a perspective of a suspended scaffolding system according to the invention (with standard scaffolding system infill used to create safe working environment); 
         FIG. 17  is an alternate perspective view of a suspended scaffolding system; 
         FIG. 18  is a transverse view of a suspended scaffolding system; 
         FIG. 19  is a transverse view of a suspended scaffolding system in free hanging position; and 
         FIG. 20  is a transverse view of a suspended scaffolding system in fixed or working position. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
       FIGS. 1A-10B  illustrate some general usage scenarios of a device according to the invention providing suspended objects stabilization by pushing them to main stable structure  30  by using force from moving the suspended object&#39;s centre of gravity  38  away from its neutral position. The centre of gravity  38  movement is caused by position adjustment of counterweight  37  component of the device. 
     Each of  FIGS. 1A-10B  show (in different configurations, mounting and usage scenarios) the same elements of the invented stabilization method: the structure  30  (building, bridge, slab, and terrace, ship . . . ) to be accessed for carrying the work from beneath  2   a : structure  30 . There are three main parts, the attachment system  31 , 32 , 33  of the suspended object/scaffolding which is the connection to the structure  30 , a suspended object/suspended working platform  34 , 35 , 36 , 37 , 39 ; and additional features such as scaffolding  40 ,  41 ,  42 . 
     The attachment system  31 , 32 , 33  comprises a fixture including one or more fixing points or a rail  31 , temporarily or permanently fastened to the structure  30 . 
     For applications in which the suspended object is movable along the length of the structure, a rail  31  is provided for attachment to the structure  30  and one, two or more independent carriage/truck sets  32  are provided which roll within the rail  31  connected via a pin mounted in a bearing  33  at the end of the suspended object/suspended working platform beam or arm  34 , 39 . 
     The fixing system includes a spherical bearing  33  or Cardan mount or any other bearing solution allowing rotation in any plane. The suspended object/suspended working platform frame is represented here by the suspended object/suspended working platform beam or arm  39  ( FIGS. 1A-1B and 2A-2B  only), vertical mounted down arm/frame  34 , and a horizontal working part of the platform  35 , with adjustable (angle and length) bumpers/buffers end  36 . The use of the platform  35  as a working environment would require optional add-in for example: allowing access horizontal platform  40 —any scaffolding system or other, scaffolding stair tower access  41 —any scaffolding system or other, lower working level horizontal platform  42  with side bars—any scaffolding or formwork system. 
     The whole suspended object/suspended working platform  34 , 35 , 36 , 37 , 39  in a free hanging position ( FIGS. 1A-1B, 3A-3B, 5A-5B, 7A-7B, and 9A-9B ) is hanging freely on two or only one support points  31  vulnerable for example for the wind pressure, not stabilized, even free swinging, with the possibility of hitting the structure  30  if prevention measures are not taken against that (i.e. Dumpers can be used to reduce swinging caused by wind). 
     In examples where the support points  31  are provided on a rail, in this configuration—hanging freely—the suspended object is easily movable along the length of the structure and can pass obstacles. 
     The suspended working platform  34 , 35 , 36 , 37 , 39  comprises suspended object/suspended working platform beam or arm  39  through which the suspended object is attached to the structure  30 , vertical side frames  34 , a horizontal frame of working platform  35  and bumpers/buffers  36  for abutment to the underside  29  of the structure  30 . The angle and length of the bumpers and buffers  36  are adjustable according to need. In the free hanging position ( FIGS. 1A-1B, 3A-3B, 5A-5B, 7A-7B , and  9 A- 9 B) there is no contact of bumpers/buffers  36  with the main structure  30 . 
     The stabilization effect of the free hanging object to the main outer structure  30  is achieved by adding a counterweight  37 , to the suspended object/scaffolding, and adjusting this counterweight&#39;s position. The counterweight can be moved and locked in different positions in relation to the suspended object/scaffolding, for example by the use of rails and hydraulic jack). 
     When the centre of gravity  38  of the whole hanging structure (suspended working platform  34 , 35 , 36 , 39  and counterweight  37  and possibly workers, equipment and materials as well as add-on accessories) is in a neutral position, it lies within a strictly vertical plane B below the upper attachment point/points  31 , then the whole structure is hanging freely—like the scheme pictured on  FIGS. 1A-1B, 3A-3B, 5A-5B, 7A-7B , and  9 A- 9 B. 
     When the counterweight part  37  of the whole suspended working platform  34 , 35 , 36 , 39  is intentionally repositioned in direction C opposite the main outer structure location  30  i.e. away from the centre of the structure  30  or towards an outer edge of the structure  30 , then the centre of gravity  38  of the whole structure (suspended working platform  34 , 35 , 36 , 39  and counterweight  37  and possible workers, equipment and materials as well as add-on accessories) is moved off its neutral position—like the schemes pictured in  FIGS. 2A-2B, 4A-4B, 6A-6B, 8A-8B, and 10A-10B . 
     In this position, the main acting force—the gravity, is forcing the shifted centre of gravity  38  back towards neutral position which is exactly within a strictly vertical plane below the upper attachment point/points  31 . However, this movement is prevented by the bumpers/buffers, that indicated force F 3  is then transferred into the structure  30  via bumpers/buffers  36 , and the passive resistance of the structure  30  gives the stability to the whole equipment. The suspended object/suspended working platform remains then in the stabilized, locked-in, working position, as pictured in  FIGS. 2A-2B, 4A-4B, 6A-6B, 8A-8B, and 10A-10B . 
     Note: the forces diagrams of  FIGS. 1B, 2B, 3B, 4B, 5B, 6B, 7B, 8B, 9B, and 10B , show only main vertical forces acting F 1 , F 2 , F 3 , and F 4  on the components; where F 1  force is a vertical component of reaction force on the main structure  30  in the place of upper supporting/fixing point/points or rail; F 2  force is a gravity force of the whole suspended object; F 3  force and/or F 4  force is/are present only for locked-in stabilized position ( FIGS. 2A-2B, 4A-4B, 6A-6B, 8A-8B, and 10A-10B ), as a vertical component or reaction force, when the suspended object/suspended working platform  34 , 35 , 36  is locked in working position by counterweight  37  displacement and passive resistance on the base structure  30  provides a brace. 
     In the free hanging position of the suspended object ( FIGS. 1A-1B, 3A-3B, 5A-5B, 7A-7B, and 9A-9B ) the F 2  acting gravity force is lined up with the F 1  re-acting force of the supporting main structure  30 , and the system is in equilibrium. In the locked-in stabilized position ( FIGS. 2A-2B, 4A-4B, 6A-6B, 8A-8B, and 10A-10B ) the F 2  acting gravity force is displaced from the line of the F 1  re-acting force of the supporting main structure  30 , and the system has a horizontal component reaction force forcing the shifted centre of gravity  38  towards it neutral position strictly under the attachment point/points  31  to the main structure  30 . The other component forces (horizontal) would be: wind pressure and horizontal component force of F 3  reaction, as the bumper  36  pushes on the angled surface of main structure  30 . All horizontal forces would be transmitted onto the structure  30  via the attachment system  31 , 32 , 33  and bumpers  36 . 
       FIGS. 1A-1B, 3A-3B, and 5A-5B  show the diagrams of the technical stabilizing device and main vertical components of acting forces F 1 , F 2  scheme showing suspended object (example: Suspended Working Platform—SWP)  34 , 35 , 36 , 39  in free hanging and moveable/passable position, respectively for the options of upper, underside and side surface fixing to the main structure  30 . In the free hanging position of the suspended working platform  34 , 35 , 36 , 39  the counterweight  37  is used as a member to balance required geometry of the whole equipment (for example when in the process of moving from one to the other work location along the structure). The counterweight  37  position is to be adjusted manually or mechanically, operated from the working platform  35  or elsewhere by remote control. 
       FIGS. 2A-2B, 4A-4B, and 6A-6B  show the diagrams of the technical stabilizing device and main vertical components of acting forces F 1 , F 2 , F 3  scheme showing suspended object (example: Suspended Working Platform—SWP)  34 , 35 , 36 , 39  in stabilized, locked-in for work position, respectively for the options of upper, underside and side surface fixing to the main structure. In the locked-in, secured and stabilized working position of suspended working platform  34 , 35 , 36 , 39  the counterweight  37  is acting as a member generating the pushing/locking force, bracing the suspended object  34 , 35 , 36 , 39  to the main structure  30 . The repositioned and lockable counterweight  37  shifts the centre of gravity off its neutral position and acts here as the member generating the pushing/locking force on one or two bumpers ends  36  from the re-action of the structure  30 , providing the required safe and stable working environment. 
       FIGS. 7A-7B and 8A-8B  show the diagrams of the technical stabilizing device and main vertical components of acting forces F 1 , F 2 , F 3 , F 4  scheme; showing suspended object (example: Suspended Working Platform—SWP)  34 , 35 , 36  respectively in free hanging, moveable/passable position ( FIGS. 7A-7B ) and working position ( FIGS. 8A-8B ) for the option of in-slot, upper surface fixing to the main structure  30 , when the suspended working platform  34 , 35 , 36  is beneath the twin/mirrored main structures  30  or beneath the main structure  30  with a slot, and the suspended working platform  34 , 35 , 36  is cantilevered, serving both sides underneath the structures  30 ; The counterweight  37  is acting here as a balance stabilizer for the total weight of workers, the suspended working platform, materials and equipment, and (using counterweight  37  adjustable position) as the member generating the pushing/locking force on one of two bumpers ends  36  from the re-action of the structure  30 , providing the required safe and stable working environment. 
       FIGS. 9A-9B and 10A-10B  show the diagrams of the technical stabilizing device and main vertical components of acting forces F 1 , F 2 , F 3 , F 4  scheme; showing suspended object (example: Suspended Working Platform—SWP)  34 , 35 , 36  respectively in free hanging, moveable/passable position ( FIGS. 9A-9B ) and working position ( FIGS. 10A-10B ) for the option of internal underside surface fixing to the main structure  30  (for example bridge of this specific geometry cross section, or cave), when the suspended working platform  34 , 35 , 36  is beneath the main structure  30 , and the suspended working platform  34 , 35 , 36  is cantilevered, serving both sides underneath the structure  30 ; The counterweight  37  is acting here as a balance stabilizer for the total weight of workers, the suspended working platform, materials and equipment, and (using counterweight  37  adjustable position) as the member generating the pushing/locking force on one of two bumpers ends  36  from the re-action of the structure  30 , providing the required safe and stable working environment. When the working platform is in the free hanging position (not stabilized, locked-in) the counterweight should be placed in such equilibrium position that neither of bumper ends  36  should be in contact with the structure. 
       FIGS. 11-20  show various aspects of an embodiment of this invention: the SWP™—Suspended Working Platform forming part of the SSS™—Suspended Scaffolding System. 
       FIG. 11  shows a frame  110 , 111  for a suspended working platform  100  of suspended scaffolding system and a rail or track  120  onto which the frame  110 , 111  is mounted. 
     The rail  120  is secured to a structure  30 , such as a bridge, using spaced apart distance supporting pads  126  (see  FIG. 18 ) underneath the rail  120  and rail fasteners/clamps  122  which can bridge over the rail  120  if needed. The rail  120  has a guideway  124  running longitudinally along its&#39; length into which a carriage/truck  112  is located. The carriage/truck  112  has wheels which are adapted to run along the rail  120 , within the guideway  124 . The carriage/truck  112  is connected to a pivotable arm  114  of the frame  110 , 111  and is moveable along the rail  120  until it intersects with a fastener  122 . The rail  120  is positioned such that the guideway  124  is substantially aligned with the span of the structure  30  Le. along the longitudinal axis A-A of the structure. 
     The suspended working platform—SWP  100  includes frame having a base portion  111  and two side portions  110  which are disposed on opposite sides  110 ′, 110 ″ of the base portion  111 . At the distal end of each of the side portions  110  a pivotable arm  114  is provided. The frame base  111  is, in use, partially suspended beneath a structure  30  via the frame sides  110  and the pivotable arms  114 . 
     The base  111  includes a counterweight system  140  which comprises a counterweight  142  which is moveable between working positions as shown and a non-working or passable position (see  FIGS. 19 and 20  for more information). The counterweight  142  moves along a pair of counterweight rails  144  using a counterweight carriage  148 . The movement of the counterweight  142  is facilitated in this example using a hydraulic jack  152  powered by a motor (not shown). 
       FIGS. 12A-12B  show a perspective of an attachment system for attaching a pivotable arm  114  of the SWP—Suspended Working Platform frame  110 , 111  to a rail  120 . 
     The pivotable arm  114  includes an aperture  218  in which a spherical bearing  118  is housed. The carriage/truck  112  has two vertically disposed extensions  212  in between which the pivotable arm  114  is located. The extensions  212  each have an aperture (not shown) which align with each other and the aperture  218  of the pivotable arm  114  enabling a pin  214  or other fastener to secure the pivotable arm  114  to the carriage/truck  112  via the spherical bearing  118 . When the carriage/truck  112  is moved along the rail, the pivotable arm  114  and thus the frame  110 ,  111  is moved along the rail. 
       FIGS. 13A-13B  show a perspective of a counterweight stabilizing device  140  according to the invention. A pair of counterweight rails  144  is disposed between the side portions of the frame  111  substantially parallel to the sides  110 ′, 110 ″ (see  FIG. 11 ) of the base of the frame  111 . 
     The counterweight  142  is attached to counterweight carriage  148 . The counterweight carriage  148  has wheels  248  which are adapted to run along the counterweight rail  144 . A counterweight stabilizer  150  is introduced to stabilize counterweight from swinging. A counterweight shield  146  covers the counterweight rail  144  and the wheels  248  of the counterweight carriage  148  protecting them from damage and ingress of dirt etc. . . . 
     A hydraulic jack  152  is connected to either the counterweight  142 , via mounted plate  154 , or to the counterweight stabilizer  150  and when actuated, the jack  152  moves the counterweight  142  linearly along the path of the counterweight rails  144 . Movement of the counterweight  142  is generally perpendicular to the longitudinal axis A-A of the structure  30  and this movement causes pivoting of the frame  110 ,  111  with respect to the structure  30  about rotational direction B-B between a free hanging and a working position when the frame  110 , 111  is stabilized to the structure  30 . 
       FIG. 14  is a perspective of a counterweight system  140  in free hanging position. The counterweight  142  is located within the internal space  310  of the frame base  111  i.e. the counterweight  142  is located underneath the frame base  111 . 
       FIGS. 15A-15B  show a cross-section through a rail  120  and carriage/truck  112 . The carriage/truck  112  has pairs of wheels  128  on each side of a central portion  212 . The rail  120  comprises an overhang  220  on each side which forms the rail guide  124  and the overhang  220  prevents the carriage/truck  120  from being removed from the rail  120 . The carriage/truck  112  may be a lubricated to assist in the movement along the rail  120 . 
       FIGS. 16 and 17  show different perspective views of a suspended scaffolding system  350  and  FIG. 18  is a transverse view of the suspended scaffolding system  350  with standard scaffolding infill (PERI in this case). The frame  110 , 111  is a suspended working platform and a scaffold  370  (any standard system type infill scaffolding) is erected within the frame  110 , 111  providing a safe access and working environment for construction, inspection and maintenance work. 
     An upper platform  374  provides access from the structure  30  to a first ladder  378 . In this example, an intermediate platform  376  is provided at the bottom of the first ladder  378  with access to a second ladder  380  which leads to the working platform  372 . A skilled person will understand how many, if any, intermediate platforms are required. 
     The scaffold  370  is an infill, of suspended scaffolding system and its suspended working platform and can be any required system scaffolding for example PERI, but any appropriate scaffolding system can be used. The scaffold infill  370  creates a wall  382  around the perimeter of the frame base  111  and a tower  384  around the access point and !adders  378 , 380 . At the corners  388  of the frame base  111  distal to the frame sides  110  i.e. the corners of the frame base  111  which are underneath the structure  30 , the corner upright  392  of the scaffold wall  382  extends beyond the wall height ending in an abutment bumper or buffer  390 . When the counterweight  142  is in its&#39; working position, as shown, the abutment bumper  390  abuts the underside of the structure  30 . The abutment bumper is an integrated part of this invented device, not the standard scaffolding infill. 
     The frame sides  110  are each connected to a carriage/truck  112  which can be moved along rail  120  which is connected to a structure  30  using spaced apart distance supporting pads  126  between the rail  120  and the structure  30  and rail fasteners  122  which bridge over the rail  120 . 
     The rail fasteners  122  are spaced apart by a nominal distance of around 200 cm however this can be smaller or larger depending on the structure  30 . The rail fasteners  122  fix the rail  120  and in addition act as a stop/obstruction for the scaffolding system  350  movements. In order to move the scaffolding system  350  further along the structure, a rail fastener  122  must be temporarily doubled (one in front of, the other behind the carriage to be moved) to allow one fastener to be removed or pivoted away from the rail  120 . It is preferred that the distance and multiples of the distance between rail fasteners  122  is not the same as the distance between the two frame sides  111  so only one fastener  122  is removed or displaced at a time to allow passage of the scaffolding. 
     In this example, in order to move the scaffolding system  350  further along the structure, a rail support  122  must be removed or pivoted away from the rail  120 . Again, it is preferred that the distance and multiples of the distance between rail fasteners  122  is not the same as the distance between the two frame sides  111  so only one fastener  122  is removed or displaced at a time to allow passage of the scaffolding. 
       FIGS. 19 and 20  are cross sections through a suspended scaffolding system in free hanging position and working position respectively. Referring to  FIG. 19 , the scaffolding system  350  is in its&#39; free hanging or first position with the counterweight  142  located beneath the frame base  111  and the abutment bumper  390  not in contact with the underside of the structure  30 . In this configuration, the scaffolding system  350  may be moved along the rail  120  enabling work, inspection or maintenance of a new section of the structure  30 . 
       FIG. 20  shows the scaffolding system  350  in a fixed or working or second position. The counterweight  142  has been displaced or moved lineally using the jack  152  towards the edge of the structure  30  and the frame sides  110  shifting the centre of gravity of the scaffolding system  350  and causing it to rotate in rotational direction B-B (see  FIG. 11 ) via the pivoting arms  114  and forcing the abutment bumper  390  into contact with the underside of the structure  30 . In other words, the counterweight  142  is moved away from the structure  30  to produce the force that pushes the suspended scaffolding towards the main stable structure. This creates a stabilizing force or brace for the scaffolding system  350  enabling work to be carried out safely, without the working platform experiencing dangerous uncontrollable swings or movement 
     Some or all of the scaffolding system  350  may be removed from a structure  30  when not in use as the scaffolding  370  is easy to dismantle and transport, the frame sides  110  could be unbolted from the frame base  111  and the rail  120  removed. Alternatively, the scaffolding system  350  is left attached to a structure  30 . 
     The hydraulic jack may be supplemented by a hand crank in case of failure or replaced by a hand crank or alternative movement options. 
     In the examples shown and described herein, the rail or track  120  is shown as being located on the upper surface of the structure  30  (see  FIGS. 1A-1B, 2A-2B, 7A-7B , and  8 A- 8 B) however the rail may be located on the roadway surface, on a side (see  FIGS. 5A-5B and 6A-6B ) or underside surface (see  FIGS. 3A-3B, 4A-4B, 9A-9B , and  10 A- 10 B) of the structure; the position chosen will depend in part on the design of the structure and the manner of access to the site and the suspended working platform of suspended scaffolding system. 
     One use of the suspended working platform  100  is to provide under bridge access for carrying the construction, maintenance or inspection work to the lower and side surface of the structure  30 . The suspended working platform  100  is delivered on the required work site in parts (dismantled or folded), then the main frame (side frames  110  and horizontal working platform  111 ) and other structural parts of S\NP are assembled together and attached to the supporting fixing points or rail  120  (by crane for example from below, or from above; by chopper; by sea ship crane)” Then the whole optional add-on accessory ( 372 , 374 , 376 , 378 , 380 , 382 , 384 , 390   FIGS. 16, 17 ), machines, formwork and materials would be placed as required. The SWP allows economical assembling, disassembling and transportation. Compared with the case of building up scaffolding to carry out the construction or maintenance, work efficiency is high, and cost can be considerably reduced. The members of the SWP are designed to be easily connected together for on-site completion, or can be pre-assembled and shipped complete to the job site. 
     SWP frame  100  has adjustable geometry and structure according to particular case and purposed use and is erected to the geometrical form of the structure  30 . The dimensions and geometry of the SSS— Suspended Scaffolding System equipment varies in each particular case of use, adjusted to specific needs, the geometry of the structure to be work subject and the specific requirements of the work type to be carried out, for example: 
     For light maintenance jobs the working platform would be relatively long, as the work progress is quick, and used equipment is light (i.e. painting, cleaning . . . ) 
     For the work to be carried in one particular place, the working platform would be relatively short (i.e. stressing . . . ) For formwork job type the working platform would be deep and high to cover the work area and carry the formwork equipment 
     It is to be appreciated that these Figures are for illustration purposes only and other configurations are possible. 
     The invention has been described by way of several embodiments, with modifications and alternatives, but having read and understood this description further embodiments and modifications will be apparent to those skilled in the art. All such embodiments and modifications are intended to fall within the scope of the present invention as defined in the accompanying claims.