NZ621411B2 - Apparatus for bridges - Google Patents

Abstract

Disclosed is a bridge maintenance personnel platform for use on a bridge so that the counterweight is contained within a secondary passageway such as a walkway or cycle lane and does not extend out into the vehicle lanes so traffic flows remain unimpeded. The bridge has an upper load surface and at least one peripheral edge. The platform apparatus includes a platform for suspension beyond the peripheral edge of the bridge and a counterweight for placement on the bridge adjacent said peripheral edge. A rigid connector, rigidly connects the platform and counterweight together and extends between the platform and counterweight. The counterweight placement on the bridge surface is static and excludes placement on any mobile mechanism or platform such as a vehicle, wheels, tracks or the like. The counterweight is configured to fit solely within the secondary passageway to avoid extending onto the primary transport passageway and disrupting traffic thereon and the counterweight incorporates a walkway permitting passage through the counterweight. The connector and/or the connections to the counterweight and platform are unarticulated. least one peripheral edge. The platform apparatus includes a platform for suspension beyond the peripheral edge of the bridge and a counterweight for placement on the bridge adjacent said peripheral edge. A rigid connector, rigidly connects the platform and counterweight together and extends between the platform and counterweight. The counterweight placement on the bridge surface is static and excludes placement on any mobile mechanism or platform such as a vehicle, wheels, tracks or the like. The counterweight is configured to fit solely within the secondary passageway to avoid extending onto the primary transport passageway and disrupting traffic thereon and the counterweight incorporates a walkway permitting passage through the counterweight. The connector and/or the connections to the counterweight and platform are unarticulated.

Description

TITLE: Apparatus for bridges TECHNICAL FIELD The present invention relates to an apparatus for use on bridges and other raised structures and more particularly to an apparatus with suspended work platforms.

BACKGROUND ART Bridge inspection and maintenance apparatus are used to enable access to ns of bridges and similar structures that are not easily or practically accessible from the bridge itself e.g. the sides or underside of the bridge. Reference to a e’ herein should be understood to e any structure spanning a gap supporting a transport passageway such as a road, walkway, cycleway, y or similar and includes bridges, walkways, skywalks, road overpasses. Existing bridge maintenance apparatus typically fall into two categories, namely: a) ‘articulated’ maintenance apparatus, comprising work platforms located on the ends of articulated arms or scissor lifts. The articulated arm or scissor lift is mounted to a vehicle and can be manoeuvred beneath the bridge or parallel to an adjacent side of the bridge. The vehicle can be moved across the bridge span to enable access at any point of the bridge.

Examples of maintenance apparatus with articulated arms are described in US patent number 4,569,416 by Stokoe and 3,456,756 by Price. Alternatively, conventional r lift work platforms can be used where vehicle access can be obtained beneath the bridge, e.g. under road overpasses. b) -and-pulley’ systems comprising a platform connected via cables to a winch so that the platform can be raised or lowered. Examples of cable-and-pulley systems include conventional skyscraper window ng platforms and the apparatus described in US patent number 055 by Beeche.

There are a number of disadvantages in such bridge maintenance apparatus.

Firstly, vehicle mounted apparatus necessarily occupy at least a n of the road/railway on or under the bridge and therefore block or at least hinder c when in use. Blocking road lanes can incur significant cost and inconvenience as:  extra staff may need to be employed to l traffic  available work times may be limited to off-peak traffic times such as early morning and for short periods of time only. Additionally, in extended work schedules the apparatus cannot be left in place and must be removed after each session and then setup before the next work session, thereby incurring further costs. ly, such apparatus are only suitable for inspection and light maintenance operations such as painting. Heavy duty maintenance/repair work such as impact drilling can cause movement of the suspended platform, compromising safety and making work ult.

Thirdly, such apparatus have linkages, s, hydraulic rams, hinges, winches or other flexible components that present potential for failure that could disrupt the operation or mise safety.

It would thus be advantageous to provide a bridge work rm that can be utilised without blocking traffic, is safe and stable.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

All references, ing any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to nge the accuracy and ency of the cited documents. It will be clearly understood that, gh a number of prior art ations are referred to herein, this nce does not constitute an admission that any of these documents form part of the common general knowledge in the art, any country.

It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non- specified ents or elements. This rationale will also be used when the term ‘comprised’ or 'comprising' is used in relation to one or more steps in a method or process.

Further s and advantages of the t invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION According to a first aspect of the present invention there is provided an apparatus for use on a bridge having an upper load surface and at least one eral edge, the apparatus including:  a platform for suspension beyond the peripheral edge of the bridge;  a counterweight for placement on the bridge adjacent said peripheral edge, and  a rigid connector, rigidly connecting the platform and counterweight together and extending between the platform and counterweight.

A ‘bridge’ as referred to herein will be used generally to denote an structure traversing a void of some form, supporting transport passageways such as a road, walkway, cycleway, railway or similar and includes bridges, walkways, skywalks and road overpasses. It should also be appreciated the present invention may also be utilised on other structures such as oil rigs, ships and buildings and thus nce to ‘bridge’, though preferred, should not be seen to be limiting.

For ease of reference, the ‘bridge’ as ed to herein will comprise an upper load surface with a primary transport passageway (e.g. a road or railway) and a secondary transport eway (e.g. a footbath, cycleway, road verge or similar) located between the peripheral edge and the primary transport passageway.

The bridge preferably includes a ‘bridge side’ extending substantially orthogonally from the load surface of the bridge and having inner and outer bridge sides respectively orientated toward and away from said load surface.

Bridge ‘maintenance’ as discussed herein refers to any work performed on a bridge and by way of example includes inspection, construction, modification, attaching fixtures, painting, repairs, fixing of screens, fences and other components or any other work.

A ‘rigid’ connection, as referred to herein, should be understood to refer to a ntially rigid tion between two components preventing significant relative on therebetween.

Preferably, the counterweight placement on the bridge e is static. As used herein, the term ‘static’ placement refers to placement directly on the bridge surface or any stationary intermediate object and excludes placement on any mobile mechanism or platform such as a vehicle, wheels, tracks or the like.

The counterweight is preferably configured to fit solely within the secondary passageway to avoid extending onto the primary transport passageway and disrupting traffic thereon. ably, the counterweight may have a dimension extending ersely to the bridge side, hereinafter ‘width’, of at least 1.5 metres and in a further embodiment may have a width of between 1.5 and 3 metres.

Preferably, the connector and/or the connections to the counterweight and platform are unarticulated. As used herein the term ulated’ should be understood to refer to two components joined together with a flexible joint or similar permitting relative rotation of the two components. Preferably, the connector is fixed in position relative to the counterweight and/or platform when the platform is suspended from the connector.

Preferably, at least one said connection to the counterweight and platform is not formed solely via a cable.

The rigid connections between the rweight, connector and platform prevent any significant movement of the platform y providing a stable platform enabling work to be med safely. ably, the tus may be configured in a transport configuration, wherein the platform, tor and counterweight are disconnected and an operating configuration, wherein the platform, connector and counterweight are rigidly connected together and the platform is suspended beyond said peripheral edge.

Preferably, the counterweight is not attached, d or fixed to the bridge and is maintained in its static position solely by virtue of its weight.

The counterweight opposes the torque applied by the ded platform about a fulcrum typically extending along a lower edge of the counterweight nearest the inner bridge side.

The counterweight is preferably configured and dimensioned to apply a torque about the fulcrum at least three times r than that of the suspended work platform. It will be appreciated that the torque applied can be varied by varying the weight and/or weight distribution in the counterweight relative to the fulcrum.

Thus, preferably the platform, connector and counterweight are constructed and weighted such that the torque applied by the counterweight and any connector n located on or over the bridge is at least three times the torque applied by the suspended platform and any connector portion over the bridge side given the lower edge of the counterweight t the bridge side as the reference fulcrum.

The counterweight preferably incorporates a walkway permitting passage h the counterweight. The counterweight therefore not only avoids disrupting bridge vehicular traffic but also minimises disruption to foot traffic.

The counterweight preferably includes a frame with one or more weights located therein. The weights may be formed from any suitable material but are ably concrete blocks or panels.

The frame may include slots for receiving the weights or the weights may be attached by bolts, chains, cables or other restraints. Where slots are provided the slots are preferably located in the opposing side of the frame to the rm. The slots may also be shaped to receive the concrete panels.

In an alternative embodiment, the counterweight may have weights located in a lower base portion of the counterweight.

The platform may include a scaffold, framework and/or housing.

The work platform preferably comprises a lower base located within a rigid frame that is rigidly connected to the connector.

In many applications, e.g. when the bridge is a road or rail overpass, the bridge may extend over roadways, railways or public areas and there is a risk of falling debris form the work platform posing a hazard. Therefore, the frame preferably includes means for preventing items falling from the platform during use and preferably es screens or walls and a tray in the lower base.

The platform preferably includes a ladder ing access to an upper portion of the frame.

The platform preferably also includes at least one lug enabling attachment to a crane for lifting the platform into place or onto a vehicle for transport.

Preferably, the connector is releasably attached to the rm and/or counterweight.

The connector is preferably formed with ment points to the counterweight and platform.

In one embodiment a pair of connectors are provided, each connector rigidly connecting the platform and rweight.

The platform is preferably slideably adjustable relative to the tor.

Preferably, the platform is vertically slideably adjustable relative to the connector.

Preferably, the connector includes a spacing mechanism for ng the spacing of the suspended platform from the bridge side.

The spacing mechanism preferably includes a laterally extending support beam and a sliding guide frame ted to the platform and slideably connected to the beam. ing to another aspect of the present invention there is ed a method of operating a bridge maintenance apparatus as aforementioned, said method including the steps of:  connecting the connector to the counterweight;  placing the rweight on a bridge sidewalk;  suspending the platform from the connector.

In a further embodiment, the method may include the further steps of:  slideably adjusting the position of the platform relative to the counterweight.

BRIEF DESCRIPTION OF DRAWINGS Figure 1 shows an isometric view of a bridge maintenance apparatus according to one preferred embodiment of the present ion; Figure 2 shows another isometric view of the bridge maintenance apparatus of Figure 1; Figure 3 shows an end on view of the bridge maintenance apparatus of Figures 1-2; Figure 4 shows another isometric view of the counterweight of the bridge maintenance tus of Figures 1-3; Figure 5 shows an isometric view of a bridge maintenance apparatus ing to a second preferred embodiment; Figure 6 shows an isometric view of the connectors of the bridge maintenance tus of Figures 1-3 and Figure 5.

Figure 7 shows an isometric view of the sliding guide frame of the bridge maintenance apparatus of Figure 5.

BEST MODES FOR CARRYING OUT THE INVENTION Table of drawing references 1 Maintenance apparatus 200 Counterweight 2 Bridge 201 Counterweight frame 3 Bridge side 202 y 4 Sidewalk 203 Weight slots 100 Platform 204 Concrete panels 101 Sliding guide frames 205 Connector beam slots 102 Sliding guide frame projections 206 Connector pins 103 Sliding guide frame hooked 207 Slot apertures projection 104 g guide frame pad 208 Counterweight ladder 105 Sliding guide frame bolt holes 209 Lifting lugs 106 Sliding guide frame vertical 210 Fulcrum 107 Sliding guide frame sleeve 300 Connector locking apertures 108 Guide frame locking tube 301 Connector support beams 109 Lifting lugs 302 Connector upright 110 Platform frame 303 tor bracing 111 Corner posts 304 Hooked connector plates 112 Post locking apertures 305 Beam bolt hole 113 Platform tray walls 306 Beam flange bolt holes 114 Platform ladder 307 Beam flange 115 Platform tray 308 End cap plates 116 Screens 309 Lifting lugs 117 Sliding guide frame tube 118 Corner post locking plates With respect to figures 1-3 there is provided a bridge maintenance apparatus (1) ing to one preferred embodiment of the present invention. A bridge (2) is shown in the drawings as a partial The apparatus (1) is composed of a platform (100) for suspending adjacent a l side (3) of the bridge (2), a static counterweight (200) for placement on a sidewalk (4) of the bridge (2) adjacent the bridge side (3) and two non-articulated tors (300) rigidly ted to the platform (100) and counterweight (200).

The counterweight (200) is dimensioned to fit on the sidewalk (4) and thus does not occupy any of the transport way (e.g. road, rail, cycleway) of the bridge (2). Prior art bridge inspection vehicles necessarily occupy the transport way and therefore disrupt traffic, in contrast to the present invention.

The counterweight (200) includes a static frame (201) incorporating a walkway (202) permitting passage through the counterweight (200). A series of slots (203) are provided in the frame (201) on the opposing side of the frame (201) to the bridge side (3) and receive weights provided in the form of concrete panels (204). Only two panels are shown inserted in the apparatus shown in Figures X-X to exemplify they can be removed.

The counterweight (200) is rigidly connected to the suspended platform (100) by connectors (300) formed as braced beams (301) ing over the bridge side (3) from tions to the counterweight frame (201).

The connectors (300) are each formed with the support beam (301) welded to an upright (302) at one end and a brace (303) extending between the distal end of the upright (302) to a weld plate on the beam (301). The triangle thus formed provides a strong and rigid tor (300).

The connector-frame connections include:  slots (205) that receive the ends of support beams (301), and  upper pins (206) to which hooked anchor plates (304) of the connector (301) are ed.

The beams (301) are locked in place in the receiving slots (205) by locking pins or bolts (not shown) that pass through apertures (207) in the slot walls and through a bolt-hole (305) in the beams (301).

The connector (301) is thus rigidly connected to the counterweight (200) but can be disconnected for ease of ort and storage.

The connectors (301) when installed are coupled to a rm spacing ism ed in the form of a pair of sliding guide frames (101) that are capable of sliding over the corresponding tor support beams (301).Each sliding guide frame (101) includes a pair of projections (102) that are supported by the corresponding support beam (301). The projections (102) distal to the counterweight (200) include hooks (103) preventing transverse movement of the sliding guide frame (101) to the support beam (301).

Each projection (102) also includes a lower pad (104) constructed from UHMWPE (Ultra High lar Weight PolyEthylene) or similar low-friction material to ensure the sliding guide frame (101) can be moved easily over the support beam (301).

The sliding guide frames (101) are also connected to a frame (110) of the platform (100) and thus the on of the platform (100) relative to the bridge side (3) can be adjusted. This adjustability ensures that the apparatus (1) can be easily adjusted for use on bridges (2) with ent bridge side widths. The g guide frame (101) also allows the suspended platform (100) to be installed without hindrance from the bridge side (3) and then manoeuvred into place abutting the bridge side (3).

The sliding guide frames (101) also include three bolt holes (105) that are aligned with a series of bolt holes (306) in locking flanges (307) on the support beams (301). The sliding guide frames (101) can thus be locked in a horizontal position by aligning one of the three sliding guide frame holes (105) with a corresponding flange hole (306) and passing a bolt through both to secure the position of the sliding guide frames (101) relative to the support beams (301). The spacing between the sliding guide frame holes (105) is not the same as the spacing between the flange holes (306) thus any of the three sliding guide bolt holes (105) can be used to align with one of the flange holes (306) thereby providing a finer level of adjustment relative to a single sliding guide frame hole. It should be appreciated that the number and g of the sliding guide frame alignment holes (105) and t beam flange holes (306) may be varied without departing from the scope of the present invention.

In alternative embodiments (not shown) the spacing mechanism may comprise telescoping rods, detent systems or other similar spacing mechanisms that allow the sliding guide frame (101) to be fixed in one of multiple positions relative to the support beams (301).

The sliding guide frames (101) include ally extending sleeves (106) with square cross-sections through which corresponding corner posts (111) of the platform frame (110) pass. The corner posts (111) can slide vertically in the sleeves (106) and can be locked in position by passing a bolt or locking pin through locking apertures (107) in the sleeves (106) and one of a series of transverse corresponding apertures (112) provided in the corner posts (111). The vertical on of the platform (100) can thus be adjusted to suit the bridge (2). It will be appreciated that it may be unsafe to adjust the al position of the platform (100) when suspended and thus any vertical ment of the platform (100) is therefore preferably made before the rm (100) is suspended over the bridge side (3).

End cap plates (308) on the support beams (301) prevent the sliding guide frames (101) from sliding completely off the support beams (301).

The platform (100) has a lower base formed as a tray (115) with a perimeter of low walls (113) for preventing any dropped items or liquid falling from the platform (100). The tray (115) extends beneath the bridge side (3) so that the platform (100) can be moved to abut the bridge side (3) while still catching any falling debris that may otherwise fall between the rm (100) and bridge side (3). The platform frame (110) extends s from the tray (115) and has three walls formed from screens (116) for preventing items falling off the platform (100). The platform (100) thus provides an enclosed ace, protecting the workers from falling and preventing items from falling off the platform (100).

An access ladder (114) is provided on the platform (100) and another ladder (208) oned nearby on the counterweight frame (201) to provide safe access to the rm (100).

The installation of the apparatus (1) involves transport of the apparatus (1) to the bridge (2) with the counterweight (200), connectors (300) and platform (100) in a disconnected state, thus being more easily accommodated on a transporter. The braced support beams (301) of the connectors (300) are then connected to the counterweight (200) and the counterweight (200) lifted into place by a crane or similar.

The platform (100) is then lifted into place with the sliding guide frames (101) positioned onto the connectors (301). The platform (100) is then manoeuvred into a suitable operating on and locked in place. The process can be reversed to relocate the apparatus (1) as needed.

To move the apparatus (1) to a new portion of the bridge (2), the sliding guide frames (101) are disconnected and the platform (100) lifted off the connectors (300). The counterweight (200) and connectors (300) are moved to the new position and the platform (100) reinstalled on the tors (300).

Lifting lugs (109, 209, 309) are thus tively provided on the platform (100), counterweight (200) and connectors (300) so that they can be lifted and manoeuvred into on. The apparatus (1) is thus easily transported on a single truck and can be installed quickly and easily.

The rigid connections between the counterweight (200), connector (300) and platform (100) prevent any significant movement of the platform (100).

The counterweight (200) balances the torque applied by the suspended platform (100) about the fulcrum which is typically along the lower edge (210) of the counterweight frame (201) nearest the bridge side (3). The counterweight (200) has a weight distribution provided to apply a torque about the fulcrum (210) at least three times the torque applied by the suspended work platform (100). The weight distribution can be altered by varying the number or weight of concrete panels (204) in the weight slots (203) or reconfiguring the counterweight frame (201) dimensions to displace the slots (203) closer or further from the fulcrum (210).

In the red embodiment the counterweight frame (201) is dimensioned to be approximately 1.5 metres in width and the overall length of the apparatus (1) is about 8 to 9 metres. It will be appreciated that these may be optimum ions to:  provide sufficient length to avoid frequent movement along the bridge length, while still being easily transportable, and  fit on sidewalks which are not typically less than 1.5 metres wide.

Alternative configurations are also possible with dimensions to suit the ular application.

The tus shown in Figure 5 is generally the same as that shown in Figures 1-4 but with a different platform (100) and sliding guide frame (101) configuration. Only the differences will thus be described. The platform screens (116) have also been removed from the drawings to aid clarity.

The platform frame (110) of the embodiment of Figure 5 has a pair of corner posts (111a, 111b) at each corner rather than a single post. The outer posts (111b) have the locking apertures (112) and are connected (typically welded) to the inner corner posts (111a) at an upper end. At the lower end of the outer posts (111b) releasable locking plates (118) are provided to ably secure the outer posts (111b) to the inner posts (111a). The locking plates (118) can be released and opened to allow the sliding guide frame (101) to be installed on the corner posts (111b). The relative position of the sliding guide frame (101) on the posts (111b) determines the height of the platform (100) relative to the connectors (300) and therefore the bridge (3). The platform (100) is thus vertically slideably adjustable.

Figure 6 shows the connectors (300) which are common to both ments. Each connector (300) has a hooked connector plate (304) for connecting to the corresponding counterweight pin (206).

The connector upright (302), bracing (303) and beam (301) form a rigid triangle. A lifting lug (309) is provided near the connection of the tor bracing (303) to the support beam (301). The connector (300) has a bolt hole (305) that along with hook (304) releasably secures the connector (300) to the rweight (200).

The beam (301) has a flange (307) with a series of flange bolt holes (306) for ing a locking pin/bolt passing through the sliding guide frame tube (117). The sliding guide frame (101) and connected platform (100) can thus be moved towards or away from the bridge (3) and locked at a position by locking pin/bolt through the sliding guide frame tube (117) and a ponding flange bolt hole (306).

End cap plate (308) ts the sliding guide frame (101) from sliding off the support beam (301) if not locked to the beam (301).

The sliding guide frame (101) shown in Figure 7 differs only from the first ment (Figures 1-4) in the replacement of the three bolt holes (105) in the previous ment with a tube (117) welded to the sliding guide frame (101) for performing the same function, i.e. receiving a locking pin passing h one of the support beam flange bolt holes (306) to lock the platform (100) in position horizontally.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.

Claims (30)

Claims

1. An apparatus for use on a bridge having an upper load e and at least one eral edge, the apparatus including:  a platform for suspension beyond the peripheral edge of the ;  a counterweight for placement on the bridge adjacent said peripheral edge, and  a rigid connector, rigidly connecting the platform and counterweight together and extending between the platform and counterweight, characterised in that the counterweight incorporates a walkway permitting passage through the counterweight.

2. An apparatus as claimed in claim 1, wherein the counterweight placement on the bridge surface is static.

3. An apparatus as claimed in claim 1 or claim 2 wherein the bridge comprises an upper load surface with a primary transport passageway and a secondary transport passageway located between the peripheral edge and the primary transport passageway and includes a bridge side extending substantially orthogonally from the load e of the bridge and having inner and outer bridge sides respectively orientated toward and away from said load surface, wherein the counterweight is configured to fit solely within the secondary passageway.

4. An apparatus as claimed in claim 3, wherein the counterweight has a ion extending transversely to the bridge side, hereinafter ‘width’, of between 1.5 metres and 3 metres.

5. An apparatus as claimed in any one of the preceding claims, wherein the connector and/or any tions to the counterweight and platform are unarticulated substantially preventing relative rotation of the counterweight and platform.

6. An apparatus as claimed in any one of the preceding claims, wherein the tor is fixed in position relative to the counterweight and/or platform when the platform is suspended from the connector.

7. An tus as claimed in any one of the preceding , wherein at least one of the connections of the connector to the counterweight and platform is not formed solely via a cable.

8. An apparatus as claimed in any one of the preceding , wherein the apparatus is capable of being configured in:  a transport configuration, wherein the platform, connector and counterweight are disconnected, and  an operating configuration, wherein the platform, connector and counterweight are rigidly connected er and the platform is suspended beyond said peripheral edge.

9. An apparatus as claimed in claim 2, wherein the counterweight is not ed, secured or fixed to the bridge and is ined in its static position solely by virtue of its weight.

10. An apparatus as claimed in any one of the preceding claims, wherein the counterweight opposes the torque applied by the suspended platform about a fulcrum extending along a lower edge of the counterweight nearest the inner bridge side and the counterweight is configured and dimensioned to apply a torque about the fulcrum at least three times greater than that of the suspended work platform.

11. An apparatus as claimed in any one of the preceding claims, wherein the counterweight includes a frame with one or more weights located therein.

12. An apparatus as claimed in claim 11, wherein the s are concrete blocks or panels.

13. An apparatus as claimed in claim 11 or claim 12, n the frame includes slots for receiving the s.

14. An apparatus as claimed in claim 13, wherein the slots are located in the side of the counterweight frame opposite the rm.

15. An apparatus as claimed in any one of claims 11-14, n the weights are ble.

16. An apparatus as claimed in any one of the preceding claims, wherein the counterweight has weights located in a lower base portion.

17. An apparatus as claimed in any one of the preceding , wherein the work platform comprises a lower base located within a rigid frame that is rigidly connected to the connector.

18. An apparatus as claimed in claim 17, wherein the frame includes a tray in the lower base and screens or walls for preventing items falling from the platform during use.

19. An apparatus as claimed in claim 17 or claim 18, wherein the platform includes a ladder providing access to an upper portion of the frame.

20. An apparatus as claimed in any one of the preceding , wherein the rm includes at least one lug enabling attachment to a crane for lifting the platform.

21. An apparatus as claimed in any one of the preceding claims, wherein the connector is releasably attached to the rm and/or counterweight.

22. An tus as claimed in any one of the preceding claims, wherein the connector is formed with attachment points to the counterweight and platform.

23. An apparatus as claimed in any one of the preceding claims, wherein said rigid connector includes a pair of connectors, each connector rigidly connecting the platform and counterweight.

24. An apparatus as claimed in any one of the ing claims, wherein the platform is slideably adjustable relative to the connector.

25. An apparatus as claimed in claim 24, wherein the platform is vertically slideably adjustable relative to the connector.

26. An tus as claimed in any one of the preceding , wherein the connector includes a spacing ism for altering the spacing of the suspended rm from the bridge side.

27. An apparatus as d in claim 26, wherein the spacing mechanism includes a laterally extending support beam and a sliding guide frame connected to the platform and slideably connected to the beam.

28. A method of operating a bridge maintenance apparatus as claimed in any one of the preceding claims, said method including the steps of:  connecting the connector to the counterweight;  placing the counterweight on a bridge lk;  suspending the platform from the connector.

29. A method as claimed in claim 28, including the further step of:  slideably adjusting the position of the platform relative to the counterweight.

30. An apparatus as substantially described herein with reference to and as rated by the accompanying drawings. 207 304 206 302 205