METHOD AND APPARATUS FOR ON-SITE MAINTENANCE OF GUARDRAILS

Abstract: For on-site maintenance of a guardrail (2) consisting of a continuous strip (6) of metal section segments (4) sup­ ported on posts (3) at joints (5) between adjacent seg­ ments (4), the guardrail (2) is split at one of joints (5) and the segments (4) of one of the resulting two por­ tions of the guardrail (2) are detached successively from the posts (3) and fed, still connected to adjacent seg­ ments (4), into an apparatus (1) traveling along the strip (6) and inside which the segments (4) are subjected con­ tinuously to cleaning, metal facing and protective pro­ cesses. Once processed, the segments (4) come out suc­ cessively from one end of the apparatus (1), as the latter travels along the guardrail (2), and are reconnected suc­ cessively to the posts (3).

Description: The present invention relates to a method for on-site maintenance of guardrails. In particular, the present invention relates to a method for the routine maintenance of metal guardrails, i.e. consisting of a series of metal section segments, usually formed from a corrugated iron section, which is normally coated against corrosion either by painting or by zinc-plating. These segments are usually bolted together into a continuous strip supported, at a given height off the ground, by posts usually located at the joints between adjacent segments, and in turn connected by one or more bolts to the above continuous strip. The routine maintenance of a guardrail of the aforementioned type normally consists in restoring its anti-corrosion coating. In case the above anti-corrosion coating is paint, it is known from U.S. Patent No. 3,532,070 to use, for carrying out the routine maintenance, a vehicle provided with a cleaning and painting unit, which is brought into engagement with the guardrail, and moved therealong to re-paint the aforementioned strip on site without detaching the strip from the relevant posts. In case of a zinc-plated guardrail, the routine maintenance usually consists in detaching the metal section segments from the supporting posts and adjacent segments, and transferring them to a maintenance plant for cleaning and zinc-plating. The processed segments are then taken back and reassembled using new bolts, the original ones invariably being damaged when dismantling the segments. Alternatively, the said segments are replaced by new ones, and stored for future use after processing. The above method presents a number of major drawbacks, both economically and technically. The major expense item involved is the labour required for dismantling and reassembling the guardrail. Whereas detaching adjacent segments off the supporting post usually requires the removal of one bolt, the separation of two adjacent segments usually involves removing eight, all of which are invariably replaced when reassembling the segments. Furthermore, once detached and separated, the segments must be transferred to a maintenance plant, and back to the assembly site after processing. A major technical drawback of the above system is the relatively time-consuming job of dismantling and reassembling the guardrail, which inevitably results in prolonged inconvenience to traffic. It is an object of the present invention to provide a method for the routine maintenance of guardrails, requiring relatively little labour and the replacement of only a limited number of parts, and which provides for substantially eliminating transport costs, and drastically reducing downtime. According to the present invention, there is provided a method for on-site maintenance of guardrails consisting of a number of posts; a number of metal section segments; a number of first joints connecting the segments into a continuous strip; and a number of second joints connecting the continuous strip to the posts; the method being characterised by comprising the steps of: splitting the guardrail, at one of the first joints, into two portions, a first of which is to be processed; successively dismantling the second joints on said first portion; moving along said first portion a mobile, continuous maintenance apparatus by which the segments on said first portion are engaged as they are detached from the respective posts by dismantling the respective second joints; the apparatus including a processing tunnel with an input for said unprocessed segments and an output for said processed segments; reconnecting said processed segments to the respective posts by reforming the respective second joints as said processed segments come out of the output, thus defining a bend moving with the apparatus along the guardrail, and consisting of a number of adjacent segments supported on the apparatus and connected by respective first joints into a continuous strip. According to the present invention, there is also provided an apparatus for carrying out the method set forth above, said apparatus being characterised by the fact that it comprises a truck; a processing tunnel on said truck, for continuously and successively processing said segments, and presenting an input and an output for the segments; and drive means for moving the truck parallel with a line joining said input to said output. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which : Fig.1 shows a schematic view in perspective of a preferred embodiment of a guardrail maintenance apparatus in accordance with the teachings of the present invention; Fig.2 shows a side view of the Fig.1 apparatus; Fig.3 shows a plan view of the Fig.1 apparatus; Fig.4 shows a side view of a guardrail portion. Number 1 in Figs. 1, 2 and 3 indicates a mobile apparatus for the maintenance of a guardrail indicated as a whole by 2. As shown, particularly in Fig.4, guardrail 2 consists of a number of posts 3; a number of in-line segments 4 formed of zinc-plated corrugated metal section; a number of joints 5 connecting the ends of adjacent segments 4 into a continuous strip 6; and a number of joints 7 connecting strip 6 to posts 3. As shown in Figs. 1 and 2, and particularly Fig.3, mobile apparatus 1 comprises a self-propelled truck 8 travelling on wheels 9, the shafts 10 of which are at least partially powered by a motor 11 housed inside body 12 and supported on frame 13, and to which shafts 10 are connected in known manner (not shown). Body 12 defines a processing tunnel 14 comprising an input duct 15 for strip 6, which duct 15 presents a number of pairs of opposed rollers 16 for guiding strip 6 to a drying chamber 17 through which the said strip 6 is dried prior to further processing. Tunnel 14 also comprises a closed-cycle sandblasting unit 18 in turn comprising a sandblasting chamber 19 immediately downstream from chamber 17 and inside which strip 6 is blasted by jets 20 with sand supplied in known manner by turbines 21 from bins 22 on frame 13. Conveyors (not shown) at the bottom of chamber 19 feed the used sand in known manner to a filtering apparatus 23 and, from there, back into bins 22. Tunnel 14 also comprises a first and second flame spraying unit, 24 and 25, arranged in line and immediately downstream from sandblasting unit 18. Unit 24 comprises a flame spraying chamber 26 wherein known metal spray guns 27, supplied by a compressor 28 and generators 29 connected to generating set 30, continuously spray strip 6 with molten metal, usually steel, for increasing the thickness of segments 4 as required. Unit 25 comprises a flame spraying chamber 31 wherein known metal spray guns 32, also supplied by compressor 28 and generators 29 connected to generating set 30, continuously spray strip 6 with a protective metal coating. As shown in Fig.3, tunnel 14 preferably also comprises a known painting unit 33 connected to compressor 28 and located between flame spraying unit 25 and an output duct 34 for strip 6, said duct 34 presenting a number of pairs of opposed rollers 35 for guiding the said strip 6. As shown in Fig.3, truck 8 also supports an external sandblasting unit 36 having an external manually-operated nozzle 37 for blasting throwaway sand supplied by turbines 21; and an external flame spraying unit 38 having an external manually-operated metal spray gun 39 connected to compressor 28 and generators 29. In actual use, truck 8 is set up on the road, adjacent to the portion of guardrail 2 for processing, so that tunnel 14 extending axially between input and output ducts 15 and 34 is substantially parallel with guardrail 2. Ground operators then dismantle joint 5 on the near end of the guardrail 2 portion for processing, by removing or, more often, breaking off the eight bolts 40 (Fig.4) of which joint 5 is composed, and then removing a further bolt 41 constituting respective joint 7. The same operators then dismantle successive joints 7, so as to detach a portion of strip 6 from posts 3, and feed the free end of strip 6 inside input duct 15 of apparatus 1. At this point, the operator in cab 42 on truck 8 starts up motor 11 so as to move truck 8 along the guardrail 2 portion for processing, at the same time feeding strip 6, detached from posts 3, along tunnel 14. As they travel along tunnel 14, segments 4 of strip 6 are successively and continuously dried inside chamber 17; sandblasted inside chamber 19; flame sprayed, if necessary, inside chamber 26 for increasing the thickness of the segments; flame sprayed with a protective metal coating inside chamber 31; and, if necessary, fully coated inside unit 33, wherein each segment 4 is coated with filler for sealing any pores left on the surface of the segments by the protective metal spray process. Once processed, segments 4, still connected by joints 5 into a continuous strip 6, come out through output duct 34, and are reconnected by further ground operators to posts 3. As the ground operators detach and replace joints 7 up- and downstream respectively from truck 8, maintenance is continued by truck 8 moving along guardrail 2, so that apparatus 1 operates along a mobile bend 43 in strip 6 supported on truck 8, with no need for dismantling joints 5. At the end of the guardrail 2 portion being processed, the far end joint 5 on bend 43 is dismantled for detaching truck 8 from guardrail 2. As truck 8 travels along strip 6, ground operators provide for manual sandblasting and protective metal spray coating of posts 3 using nozzle 37 and gun 39 respectively. The advantages of apparatus 1 according to the present invention will be clear from the foregoing description. Firstly, only joints 7 (one bolt 41) and no longer joints 5 (eight bolts 40) are dismantled along strip 6. Secondly, segments 4 are no longer separated and transferred, but remain connected along strip 6, and only bolts 41 are replaced. A major advantage, however, in addition to those mentioned above, is that apparatus 1 provides, if necessary, for continuously increasing the thickness of segments 4 via unit 24, thus eliminating the cause of existing guardrails being rejected, and which has so far remained unsolved by existing routine maintenance methods.

Claims: A method for on-site maintenance of guardrails (2) consisting of a number of posts (3); a number of metal section segments (4); a number of first joints (5) connecting the segments (4) into a continuous strip (6); and a number of second joints (7) connecting the continuous strip (6) to the posts (3); the method being characterised by comprising the steps of: splitting the guardrail (2), at one of the first joints (5), into two portions, a first of which is to be processed; successively dismantling the second joints (7) on said first portion; moving along said first portion a mobile, continuous maintenance apparatus (1) by which the segments (4) on said first portion are engaged as they are detached from the respective posts (3) by dismantling the respective second joints (7); the apparatus (1) including a processing tunnel (14) with an input (15) for said unprocessed segments (4) and an output (34) for said processed segments (4); reconnecting said processed segments (4) to the respective posts (3) by reforming the respective second joints (7) as said processed segments (4) come out of the output (34), thus defining a bend (43) moving with the apparatus (1) along the guardrail (2), and consisting of a number of adjacent segments (4) supported on the apparatus (1) and connected by respective first joints (5) into a continuous strip (6). A method as claimed in Claim 1, characterised by the fact that the maintenance processes comprise an initial drying step. A method as claimed in Claim 1 or 2, characterised by the fact that the said maintenance processes comprise a sandblasting step. A method as claimed in Claim 1, 2 or 3, characterised by the fact that the said maintenance processes comprise a step wherein the said segments (4) are metal coated. A method as claimed in Claim 4, characterised by the fact that the said metal coating step consists in increasing the thickness of the segments (4) by coating same with molten metal. A method as claimed in Claim 4 or 5, characterised by the fact that it comprises a further step wherein the segments are given a protective metal coating. A method as claimed in Claim 5 or 6, characterised by the fact that said metal coating is applied by flame spraying. A method as claimed in any one of the foregoing Claims, characterised by the fact that the maintenance processes comprise a further painting step. A method as claimed in Claim 8, characterised by the fact that the said painting step is performed using filler. An apparatus (1) for carrying out the method according to any of Claims 1 to 9, said apparatus being characterised by the fact that it comprises a truck (8); a processing tunnel (14) on said truck (8), for continuously and successively processing said segments (4), and presenting an input (15) and an output (34) for the segments (4); and drive means (11) for moving the truck (8) parallel with a line joining said input (15) to said output (34). An apparatus as claimed in Claim 10, characterised by the fact that the processing tunnel (14) comprises an initial drying unite (17). An apparatus as claimed in Claim 10 or 11, characterised by the fact that the processing tunnel (14) comprises a sandblasting unit (18). An apparatus as claimed in one of the foregoing Claims 10 to 12, characterised by the fact that the tunnel (14) comprises means (24, 25) for increasing the thickness of the segments (4) by coating same with molten metal. An apparatus as claimed in Claim 13, characterised by the fact that said means (24, 25) for increasing the thickness of the segments (4) comprise a first metal spray unit (24). An apparatus as claimed in Claim 14, characterised by the fact that the processing tunnel (14) comprises a further metal spray unit (25). An apparatus as claimed in Claim 14 or 15, characterised by the fact that each said metal spray unit (24, 25) is a flame spray unit. An apparatus as claimed in any one of the foregoing Claims 10 to 16, characterised by the fact that the processing tunnel (14) comprises a painting unit (33). An apparatus as claimed in any one of the foregoing Claims 10 to 17, characterised by the fact that it also comprises an external sandblasting unit (36) comprising a manually-operated sandblasting nozzle (37) for sandblasting said posts (3). An apparatus as claimed in any one of the foregoing Claims 10 to 18, characterised by the fact that it also comprises an external metal spray unit (38) comprising a manually-operated metal spray gun (39) for metal spraying the posts (3).

Inventors: BUSSOLINO, ROMOLO
Applicants: HASTASIDER METAL S.R.L.
Application year: 1988
Main classification: E01H1
IPC codes: E01H1