IMPROVED SAFETY SCAFFOLDING

Description

[0001] The present invention relates to an improved protective scaffold, such as that used in the construction, overhaul and / or repair of an overhead power line supported by pylons, to protect sensitive infrastructure, for example roads, railway lines, other power lines or the like, from falling cables. Field of invention

[0002] A high-performance high-voltage transmission network is essential for reliable energy transmission. It plays a crucial role in the construction of new power lines and the renovation and replacement of existing ones. One of the main tasks involved is installing new conductors or replacing existing ones. These power lines cross important infrastructure along their routes, such as highways, railway lines, other high-voltage lines, various roads of different classes, and many other locations.

[0003] During the actual work process of replacing the cable (pulling the cable), there is always a risk that, due to unforeseen or unexpected events (of a material nature, technical or human failure), the pulled cable may fall and thus endanger traffic on the ground.

[0004] To prevent this danger, special scaffolding structures with netting of appropriate height, built according to static specifications, are erected directly in the endangered zones; these are also referred to as protective scaffolding. For example, scaffold walls are erected on both sides of the road directly beneath the exposed cable lines.

[0005] Ropes are stretched between these, and then protective nets are hung from these ropes. State of the art

[0006] Today's high demands on power transmission capacity necessitate the use of increasingly stronger and therefore heavier conductor cables, which in turn result in ever greater loads and forces during cable pulling. Likewise, the dynamic loads on protective structures and scaffolding increase significantly. This is particularly true for bundled cable pulling, where two to four conductor cables, bolted together to form a bundle, are pulled by a single pulling cable using a so-called "carpet." This "carpet" typically has a width of approximately 50 to 60 cm and includes a connection point weighing around 150 kg between the pulling cable and the multiple cables being pulled into the bundle, for example, two to four cables.

[0007] The relative mass of bundled conductor cables is typically around 5 kg / m, the relative mass of a bundle of two conductor cables is up to about 10 kg / m, and the relative mass of a bundle of four conductor cables is up to about 20 kg / m. This results in a total conductor cable mass of approximately 5 t in a pylon field with a pylon spacing of about 500 m.

[0008] The conductor cables to be installed are pulled at an average height of 5 to 10 meters above the protective scaffolding and with an average tensile force of approximately 5 tons for a bundle of two cables and approximately 10 to 12 tons for a bundle of four cables. The combined effect of these forces represents an extreme dynamic load for the scaffolding structure and the safety nets in the unlikely event of a failure.

[0009] An additional major risk factor in the event of a break in the pull rope during bundle pull is the extreme dynamic impact of the "carpet" on the nets and thus an acute danger to the area to be protected, should the carpet break through the net.

[0010] Consequently, the protective structure must provide sufficient protection to catch the torn, falling cable with its dynamic behavior, whereby the damaged cable extends over a certain distance (usually about 500 m) between two high-voltage pylons.

[0011] The most important characteristic of protective scaffolding in safeguarding the area below is that the entire scaffolding structure, even under extreme stress during operation after the nets have caught the falling bundles, does not yield. This prevents the defined safety distances from being breached and ensures that bundles, ropes, carpets, or similar items do not fall onto the intersecting object. This is particularly relevant at crossing and operating high-voltage power lines and electrified railway lines, where even a breach of the safety distance of approximately 4 meters without direct contact would result in the induction voltage being carried by the power lines. This would endanger all objects within the cable pull zone, such as the scaffolding structure, high-voltage pylons, work equipment, etc.The cable section would be put under tension, which would create an extremely high risk to the lives of the people involved in the work.

[0012] The same applies to highways and roads, where the sudden falling of the crossing, pulled power cables would automatically mean an acute danger to life.

[0013] The increased demands on the operational safety of the protective structures and nets during cable pulling, especially when crossing high-voltage lines, railway lines, motorways and federal highways with network spans of up to approximately 120 meters, must be met by means of the improved protective structure according to the invention.

[0014] There are no defined standards or criteria that would allow for the determination of risks. Furthermore, no practical methods are known that would be suitable in the present application area for assuring / determining loads during bundle rupture and the impact of the resulting mechanical forces on the protective structure.

[0015] The invention disclosed below allows the risks to be largely limited and provides a basis on which the protection can be further optimized.

[0016] DE 69 413 669 T2 discloses a scaffold comprising a spaced pair of columns and connecting means, wherein each column is mounted on a transportable base in such a way that it is pivotable relative to it, and the connecting means can be attached to each column of the column pair, generally vertical, to extend between them, characterized in that each column is pivotable relative to the base from a generally horizontal orientation to a generally vertical orientation. A safety net is arranged between two pairs of columns on an upper grid section that is arranged between two columns.

[0017] EP 3 522 314 A1 relates to a protective scaffold comprising at least two elongated tower elements; an elongated top chord element arranged between the two tower elements and attached at its end to one of the two tower elements to provide a scaffold portal, wherein both tower elements are connected in the area of ​​their longitudinal end section facing away from the top chord element to an associated support element by means of a connecting device, and both support elements each have a base surface for bracing against a ground.

[0018] US Patent 2011 / 0132685 A1 discloses a scaffold side frame comprising at least one generally horizontally extending tube, a pair of vertically extending side tubes suspended from the horizontal tube, and four fasteners, one beside each corner of the frame, for attaching the side frame to a respective adjacent structural element of an associated scaffold structure, such that the upper part of the side frame forms a safety guardrail for an operator standing on a support platform of a given level of a scaffold structure, and the lower part of the side frame extends below the support platform of the given level of the scaffold structure. The two lower fasteners are hook-shaped, and the hooks have a locking latch.

[0019] EP 2 134 908 B1 discloses a closed vertical frame comprising at least two parallel vertical posts arranged at a horizontal distance from each other, each having an upper end and a lower end, and at least two parallel horizontal arms arranged at a vertical distance from each other, each extending transversely between the at least two vertical posts. General description of the invention

[0020] The object of the invention is achieved by a protective framework according to claim 1. The dependent claims describe preferred embodiments.

[0021] The invention discloses a protective scaffold designed to protect objects below a power line during work on the power line. This work may include installation, repair, maintenance, overhaul, or similar activities on the power line. The protective scaffold comprises a first scaffold section with a plurality of vertically arranged supports, which are parallel to and spaced apart from each other in the longitudinal and transverse directions of the first scaffold section. The first scaffold section also includes a plurality of horizontal beams connecting the vertical supports, which are also parallel to and spaced apart from each other. According to the invention, at least one uppermost beam has a higher mechanical strength than the average mechanical strength of the beams below it.This allows the top beam to bear a higher load if a cable, rope, carpet or other object falls onto the protective scaffold.

[0022] The protective scaffold comprises a second scaffold section with a plurality of vertically arranged supports, which are parallel to and spaced apart from each other in both the longitudinal and transverse directions of the second scaffold section. The second scaffold section includes a plurality of horizontal beams connecting the vertical supports, which are also parallel to and spaced apart from each other. At least one uppermost beam has a higher mechanical strength than the average mechanical strength of the beams below it. The second scaffold section may be spaced apart from and parallel to the first scaffold section.

[0023] In one embodiment, the two uppermost beams can have a higher mechanical strength than the average mechanical strength of the beams below.

[0024] The higher mechanical strength can be at least 25%, preferably at least 50%, more preferably at least 100%, and even more preferably at least 200% higher than the average mechanical strength.

[0025] The terms "higher mechanical strength" and "average mechanical strength" include at least the tensile modulus, the modulus of elasticity and / or the breaking load.

[0026] In one embodiment, at least one beam with higher mechanical strength can have a larger cross-section than the beams with average mechanical strength.

[0027] The beam with higher mechanical strength can be a reinforced tubular beam.

[0028] In one embodiment, the protective scaffold may include a safety cable that is largely positioned below the uppermost beam with higher mechanical strength. The safety cable may be attached to the ends of the uppermost beam with higher mechanical strength and / or to the supports to which the uppermost beam with higher mechanical strength is attached. The safety cable provides additional mechanical deceleration of a falling object should the uppermost beam with higher mechanical strength be deformed by the falling object.

[0029] The first and second scaffold sections can be arranged such that the at least one beam with higher mechanical strength in the first section and the at least one beam with higher mechanical strength in the second section are positioned opposite each other. The object to be protected, for example a traffic route, can be located between the first and second scaffold sections.

[0030] A first net is stretched between at least one uppermost beam with higher mechanical strength of the first scaffold section and at least one uppermost beam with higher mechanical strength of the second scaffold section. Additionally, a second net is stretched between at least one second-uppermost beam of the first scaffold section and at least one second-uppermost beam of the second scaffold section. This further improves the protection of the infrastructure below from falling objects.

[0031] The invention comprises several innovative structural safeguards which, in their combined effect, make it possible to safely absorb enormous loads in the event of a breakage of one or more bundled ropes during the bundled rope pulling over high-voltage pylons in one work section.

[0032] The deformation of the scaffolding structure, and thus the risk of penetration, is significantly limited or completely eliminated to prevent the associated sagging of the net cables. This ensures that the intended operating height is maintained even if the cable bundle or rope bundle rests on the scaffolding structure in the event of an accident.

[0033] Innovative, additional reinforcement measures on the load-bearing scaffold walls, such as the use of specially manufactured safety cables mounted at the top of the scaffold face, on adjacent standards, in each bay within the immediate impact zone, significantly reduce the risk of shear penetration. These statically tested safety cables are designed to absorb the dynamic load during bundle breakage and to dissipate the forces laterally, minimizing the impact at a single point. This ensures that the affected area of ​​the scaffold wall yields minimally or not at all, preventing inward tilting of the walls. The cables supporting the nets stretched between the scaffold walls thus remain at their preset height and do not sag into the critical area. Traditional designs are still used, partly due to their lower cost.

[0034] The construction methods used so far to protect objects are insufficient due to the difficult-to-assess dynamic behavior of the rope bundle and the resulting consequences regarding the penetration of the net and deformation of the supporting scaffold walls.

[0035] These loads pose significant safety challenges during cable hoisting operations, as explained below. The reinforced, layered crossbeams and the special, statically tested safety cables mounted between the uprights are designed to absorb the dynamics of the falling bundle and distribute the resulting peak loads across the surface. This largely prevents deformation of the scaffold walls. Consequently, the sagging of the net support cables is prevented, and the bundle that has fallen into the net remains at a safe height until it comes to a complete stop.

[0036] Due to the reinforced properties of the scaffold walls, which were calculated in advance, it can be practically ruled out that the area below, within the protected zone, is directly endangered. This is particularly important when high-voltage power lines and railway lines cross, as direct contact of the pulled cables with, or even simply falling below, the minimum safety distances to these lines would result in the cables inducing voltage. The fallen cables would then electrify the entire work area within the cable-pulling section, posing a direct risk to the lives of all employees working in that area.

[0037] Additional protection is achieved by installing two layers of safety netting, spaced 0.5 to 2 meters apart, depending on the specific conditions at the scaffolding site. The primary function of the upper netting layer is to absorb the dynamic impact forces when a bundle of rope and carpet falls, and to catch the bundle. The lower netting layer safely absorbs any remaining dynamic impact forces. Should the carpet fall through the upper netting, it will be caught by the lower netting. Brief description of the characters

[0038] The invention will then be explained in more detail with reference to non-limiting embodiments, wherein Figures 1 to 2 represent a general embodiment of the invention; Figures 3 and 4 disclose a first embodiment of the invention; and Figures 5 to 9 disclose a second embodiment of the invention. Detailed description of the figures

[0039] Embodiments of a grinding and protective scaffold 100 according to the invention with net covering consisting of additional horizontal reinforcement 206, 208 of the scaffold walls and with two net levels 190, 192 one below the other.

[0040] The invention is now generally referred to as Figures 1 and 2 described. Figure 1Figure 1 shows a protective scaffold 100 with a first section 102 and a second section 104. The first section 102 comprises vertical supports 106 and 108, which are arranged parallel to each other and spaced apart. Behind the vertical supports 106 and 108 are further vertical supports, which are not shown for clarity. Between the vertical supports are a plurality of horizontal beams 110, 112, 114, 116, 118, 120, and 122, each of which is attached to the vertical supports 106 and 108. Diagonal braces 128, 130, 132, 134, 136 are arranged between the vertical supports 106, 108, each brace positioned between two horizontal beams 110, 112, 114, 116, 118, 120, 122. The first section of the protective scaffold rests on feet 126 on the ground. The first scaffold section 102 is braced by means of a cable 123, which is attached to the ground by means of a ground anchor 124.

[0041] The second section of the protective scaffold 104 comprises vertical supports 150, 152, which are connected or fastened by means of a plurality of horizontal beams 154, 156, 158, 160, 170, 172, 174, and a plurality of diagonal braces 180, 182, 184, 186, 188. The diagonal braces each run between two horizontal beams 154, 156, 158, 160, 170, 172, 174. The second section of the scaffold 104 is supported from the ground by means of feet 189. Furthermore, the second section of the protective scaffold 104 is supported by means of a cable 176, which is fastened to the ground by means of a suitable fastening element, for example, a ground anchor 178.

[0042] It will be on Figure 2 Referring to the frontal view A showing the second section of the protective scaffolding from the space between the first section 102 and the second section 104, two vertical supports 200, 202 are supported by lower beams 203, 204, 205, etc. It is understood that Figure 2only shows the upper section of part of the second protective scaffold section 104.

[0043] Furthermore, the protective scaffold section 104 comprises a plurality of upper beams 206, 210, 214, each arranged between two supports 200, 202. The upper beam 206, 210, 214 is reinforced and has a higher mechanical strength than other beams 154, 156, 158, 160, 170, 172, 174, 203, 204, 205. The upper beam 206, 210, 214 with higher mechanical strength may be a reinforced tubular beam. The terms "higher mechanical strength" and "average mechanical strength" may include at least the tensile modulus, the modulus of elasticity, and / or the breaking load. In one embodiment, the at least one beam with higher mechanical strength may have a larger cross-section than the beams with average mechanical strength.

[0044] Like the uppermost beams 206, 208, 214, the second-highest beams 211, 212, 216 exhibit higher mechanical strength than other beams 154, 156, 158, 160, 170, 172, 174, 203, 204, 205. The second-highest beams 211, 212, 216 with higher mechanical strength may be reinforced tubular beams. The terms "higher mechanical strength" and "average mechanical strength" may include at least the tensile modulus, the modulus of elasticity, and / or the breaking load. In one embodiment, the at least one beam with higher mechanical strength may have a larger cross-section than the beams with average mechanical strength.

[0045] A first net 190 is prestressed between at least one uppermost beam with higher mechanical strength of the first scaffold section 102 and at least one uppermost beam 206 with higher mechanical strength of the second scaffold section 104. A second net 192 is prestressed between at least one second-uppermost beam of the first scaffold section 102 and at least one second-uppermost beam 208 of the second scaffold section 104. The primary function of the upper first net 190 is to absorb the dynamic impact forces when a bundle of rope falls with the carpet and to catch the bundle. The lower second net 192 serves to safely absorb the remaining dynamic impact forces. Should the carpet fall downwards through the upper net, it will be caught by the lower net. The first net 190 and the second net 192 are spaced approximately 0.5 m to 2 m apart.

[0046] The distance between horizontal beams can be about 2 m and the distance between vertical supports can be about 3 m.

[0047] A safety cable 219, 220, 221, located largely below the uppermost beam 214, 220, 210 with higher mechanical strength and attached to the ends of the uppermost beam 214, 220, 210 with higher mechanical strength and / or to the supports 200, 202 to which the uppermost beam 214, 220, 210 with higher mechanical strength is attached, provides additional stability to the scaffolding structure in the event of a fall of line or assembly components. In the event of an unexpectedly large deformation of the uppermost beam, the remaining kinetic and potential energy resulting from the fall of line or assembly components is transferred into the safety cable 219, 220, 221. The second uppermost beam 208, 212, 216 acts as an additional safety element to absorb even extreme peak loads.

[0048] The invention provides horizontal reinforcement for scaffold walls. Additional protection is achieved by installing special, statically tested safety cables horizontally along the top of the scaffold wall structures. This protection is further enhanced by installing reinforcements with heavy-duty bars horizontally along the top of the scaffold wall structures at three levels, spaced 0.5 to 2 meters apart.

[0049] The invention proposes remote safety nets to reinforce the structure. This additional protection is achieved by installing two safety nets one above the other, spaced 1 to 2 meters apart, with the installation depending on the specific conditions at the scaffolding site. The upper net 190 primarily serves to absorb the dynamic impact forces when a bundle of ropes falls with the carpet and to catch the bundle. The lower net 192 serves to safely absorb the remaining dynamic impact forces. Should the pull-trap fall through the upper net 190, it will ultimately be safely caught by the lower net 192.

[0050] Further embodiments are described below.

[0051] In the first embodiment according to Figures 3 and 4Each is positioned opposite reinforced load-bearing walls, between which protective nets are attached to the upper part of the walls in two levels.

[0052] In the second embodiment according to Figures 5 to 9 Supporting walls are erected opposite each other, between which protective nets are attached to the upper part of the nets in two levels.

[0053] When erecting the scaffold according to the invention, regardless of the specific embodiment, the individual components of the scaffold walls are transported to the intended assembly site in individual parts or partially pre-assembled.

[0054] The first embodiment of a grinding and protective scaffold according to the invention is constructed from scaffolding material, e.g., Layher-Allround, Peri, Plettac, additionally supplemented with technical measures according to the invention. This embodiment of a grinding and protective scaffold according to the invention has a net covering consisting of two nets one above the other. In this variant, the load-bearing walls of the protective scaffold are manufactured from scaffolding components available on the market, in particular from or of the type of scaffolding components offered by manufacturers in their product lines, such as "Layher - Allround", "PERI - UP Rosett Modular Scaffold", "ALTRAD 20 plettac-alsco Modular Scaffold", or by other manufacturers such as Rux, Hünnebeck, etc.

[0055] The second embodiment according to Figures 5 to 9Disclosing an inventive grinding and protective scaffold consisting of square lattice girders made of angle or tubular profiles, e.g., from emergency poles, and netting with two layers of netting, the load-bearing walls of the protective scaffold are manufactured in this variant from elements specifically produced for this purpose or similar elements available on the market, in particular square lattice girders made of angle or tubular profiles or emergency poles, as offered by manufacturers in their product lines, such as those offered by emergency pole manufacturers, etc.

[0056] In both designs, supporting walls (protective scaffold sections) are erected opposite each other, and protective nets are attached to and between them at two heights in the upper part.

[0057] In the first embodiment, two opposing scaffold wall constructions (protective scaffold sections) are erected from commercially available scaffold components, adapted to the respective local conditions, in particular according to the type of or from scaffold components offered by manufacturers in their product lines, such as "Layher - Allround", "PERI - UP Rosett Modulgerüst", "ALTRAD 20 plettac-alsco-Modulgerüst", or by other manufacturers such as Rux, Hünnebeck etc.

[0058] The scaffold wall structures (protective scaffold sections) are stabilized with steel cables to prevent them from tipping over. One end of the cables is attached to the top of the scaffold wall. The other end is attached to steel screw anchors that have been screwed into the ground. If, for technical reasons (utility lines), it is not possible to screw in the anchors on site, ballast blocks (type B) are used, to which the steel cables are attached at the bottom. Alternatively, the ballast blocks can be installed inside the scaffold wall structure according to the structural engineer's specifications.

[0059] In the respective scaffold wall erected beforehand, horizontally reinforced bars, heavy-duty bars, and beams with increased mechanical strength are installed at the top of its front in levels one below the other at intervals of 0.5 m to 2 m.

[0060] Additionally, in each bay, on the top level of the ledgers, along the entire length of the scaffold, specially manufactured, statically tested cables (cables with two loops at each end) are mounted onto the successive uprights (supports) by slipping the ends of each cable over the top of the individual uprights (supports). Furthermore, the cables are clamped or fastened to the heavy-duty ledgers using scaffold couplers, ensuring they run parallel to each other.

[0061] The uppermost rigid beam or girder of increased mechanical strength is designed to absorb the main impact from above and the abrasive action (sawing effect) of the subsequently laterally moving and falling ropes. The ropes mounted on the uppermost level, in the event of bending and, in the hypothetical case of the uppermost beams being sawed through, are intended to ultimately absorb the load due to their flexible properties and bring the mass and its energy to a standstill.

[0062] The two lower reinforcement levels remain undamaged, preventing further deformation of the scaffold wall. This allows the load, now at rest, to be supported at the top. Between the previously erected scaffold wall sections (protective scaffold sections), net support cables (made of steel or GRP material, called "Parafil cables") are tensioned at two levels, similar to the opposing uprights (supports), and their ends are attached to the designated points in the respective scaffold wall structure. The installation of the net support cables takes place during a road closure or temporary shutdown of the intersecting high-voltage power lines.

[0063] For the installation of the net support cables, two fitters are deployed at the top of each of the scaffold walls (scaffold wall A and scaffold wall B). An additional four fitters are deployed on each side to provide support.

[0064] When installing net support cables on level 1 at the top, a plastic pilot cable is first run from scaffold wall A to scaffold wall B. Then, one end of the net support cable to be transported is attached to the pilot cable. The net support cable is then transported from scaffold wall A to scaffold wall B. One end of the net support cable, equipped with a loop, is attached to the designated anchor point on scaffold wall B. The other end of the net support cable is anchored to scaffold wall A at the bottom using cable tension clamps. The pilot cable is then pulled back to the starting point on scaffold wall A using a pulley attached to the already installed net support cable. Further net support cables are then transported in the same way, with a pilot cable for attaching the safety nets attached to every third or fourth net support cable, using a pulley system.This ensures that the respective, pulled net support cable does not sag and that the net support cable cannot become independent.

[0065] After installation, the sag of the individual net support cables is adjusted. The installation of the net support cables on level 2 below is carried out in the same way as the installation of the net support cables on level 1 above. Safety nets are then attached.

[0066] Two fitters are deployed at scaffold wall A for the installation of the nets at the top. Three fitters are deployed at the bottom to assist with the preparation of the safety nets. For the subsequent installation of the nets, two fitters are deployed at the top of scaffold wall A. Three fitters are deployed at the bottom to assist with the preparation of the safety nets.

[0067] The safety nets are equipped with safety carabiners every 1 meter around their perimeter. These carabiners are used to attach the nets to the support cables. The nets are then transported to the installation team. They are attached to the support cables, initially hanging in an accordion-like position on scaffold wall A until it is fully assembled. Once assembled, the nets are pulled along the support cables, using guide ropes that were previously attached, to scaffold wall B. This creates a continuous safety net surface.

[0068] Finally, the protective nets are anchored to the horizontal beams on both scaffold walls to prevent movement. The nets are then installed while traffic continues and the crossing high-voltage power line remains operational. Any necessary safety measures and precautions for the safe execution of the dismantling work are implemented in advance, before the start of both the assembly and dismantling operations.

[0069] The installation of the protective nets on level 2 below is carried out in the same way as the installation of the protective nets on level 1 above.

[0070] The second embodiment of a grinding and protective scaffold according to the invention is constructed from square lattice girders made of angle or tubular profiles, for example, from emergency poles, and a net covering with two net levels. In this variant, the load-bearing walls of the protective scaffold are manufactured from elements specifically produced for this purpose or from similar elements available on the market, in particular from or in the form of square lattice girders made of angle or tubular profiles or emergency poles, as offered by manufacturers in their product lines, such as by emergency pole manufacturers, etc.

[0071] The scaffold wall structures are stabilized with steel cables to prevent them from tipping over. One end of the cables is attached to the top of the scaffold wall. The other end is attached to steel screw anchors that have been screwed into the ground. If, for technical reasons (utility lines), it is not possible to screw in the anchors on site, ballast blocks are used to which the steel cables are attached at the bottom. Alternatively, the ballast blocks can be installed inside the scaffold wall structure according to the structural engineer's specifications.

[0072] Between the previously erected scaffold wall structures (protective scaffold sections), net support cables (made of steel or GRP material, called "Parafil cables") are tensioned at the top on two levels, analogous to the opposing uprights (supports), and their ends are attached to the designated points in the respective scaffold wall structure. The installation of the net support cables takes place during a road closure or temporary shutdown of the intersecting high-voltage power lines. For the installation of the net support cables, two fitters are deployed at the top of each of the two scaffold walls (protective scaffold sections), namely the first scaffold wall A and the second scaffold wall B. An additional four fitters are deployed on each side to provide support.

[0073] When installing the upper net, a plastic guide rope is first run from the first scaffold wall (A) to the second scaffold wall (B). Then, one end of the net support rope to be transported is attached to the guide rope. The net support rope is then transported from scaffold wall A to scaffold wall B. One end of the net support rope, equipped with a loop, is attached to the designated anchor point on scaffold wall B. The other end of the net support rope is anchored to the designated anchor point on scaffold wall A using rope tension clamps. The guide rope is then pulled back to its starting point on scaffold wall A using a pulley attached to the already installed net support rope. Further net support ropes are transported in the same way, with a guide rope attached to every third or fourth net support rope for pulling the safety nets. This process is repeated back and forth using a pulley.This ensures that each suspended net support cable does not sag and cannot become detached. After installation, the sag of each individual net support cable is adjusted.

[0074] The lower net support cables are installed in the same way as the upper net support cables. Afterwards, safety nets are attached.

[0075] Two fitters are deployed at the first scaffold wall A to install the upper net. Three fitters are deployed at the bottom to assist with preparing the safety nets. The safety nets are equipped with safety carabiners around their perimeter, spaced approximately 1 meter apart. These carabiners are used to attach the safety nets to the net support cables. The safety nets are then transported to the fitters at the top. Next, the safety nets are attached to the net support cables, initially hanging in an accordion-like position at scaffold wall A until they are fully installed. Once installed, the safety nets are pulled along the support cables, which were previously attached, by means of guide ropes, sliding them towards scaffold wall B. This creates a continuous safety net surface.

[0076] Finally, the protective nets against movement are anchored to the horizontal beams on both scaffold walls. The nets are then installed while traffic continues and the crossing high-voltage power line remains in operation.

[0077] Any necessary safety measures and precautions to ensure the safe execution of the dismantling work will be taken in advance before the dismantling work begins.

[0078] The installation of the protective nets on the lower level is carried out in the same way as the installation of the protective nets on the upper level.

[0079] The invention has the advantage that the stability of the protective scaffold can be significantly increased by means of measures that are easy to implement in the field, in order to meet future requirements.

Claims

1. Protective framework (100) adapted to protect objects below a power line during work on the power line, comprising a first framework section (102) with - a plurality of vertically arranged supports (106, 108) which are arranged parallel to each other and spaced apart from each other in the longitudinal direction of the first framework section (102) and in the transverse direction of the first framework section (102); - a plurality of horizontal beams (118, 120) connecting the vertical supports (106, 108) and arranged parallel to each other and spaced apart from each other; - wherein at least one uppermost beam (122) has a higher mechanical strength than the average mechanical strength of the beams (118, 120) below it; further comprising a second framework section (104) with - a plurality of vertically arranged supports (150, 152) which are arranged parallel to each other and spaced apart from each other in the longitudinal direction of the second framework section (104) and in the transverse direction of the second framework section (104); - a plurality of horizontal beams (154, 156, 158, 160, 170, 172) connecting the vertical supports (150, 152) and arranged parallel to each other and spaced apart from each other; - wherein at least one uppermost beam (174) comprises a higher mechanical strength than the average mechanical strength of the beams below it; - wherein the second framework section (104) is spaced apart and arranged parallel to the first framework section (102), wherein the higher mechanical strength and the average mechanical strength comprise at least the tensile modulus, the elastic modulus and / or the breaking load; - wherein a first net (190) is prestressed between the at least one uppermost beam with higher mechanical strength of the first framework section (102) and the at least one uppermost beam (206) with higher mechanical strength of the second framework section (104), characterized in that a second net (192) is prestressed between the at least one second uppermost beam of the first framework section (102) and the at least one second uppermost beam (208) of the second framework section (104).

2. Protective framework (100) according to claim 1, characterized in that the two uppermost beams (120, 122, 172, 174) comprise a higher mechanical strength than the average mechanical strength of the beams (118, 154, 156, 158, 160, 170) located thereunder.

3. Protective framework (100) according to claim 1 or 2, characterized in that the higher mechanical strength is at least 25%, preferably at least 50%, more preferably at least 100%, and even more preferably at least 200% higher than the average mechanical strength.

4. Protective framework (100) according to one of claims 1 to 3, characterized in that the at least one beam (122, 174) with higher mechanical strength comprises a larger cross-section than the beams (118, 120, 154, 156, 158, 160, 170, 172) with average mechanical strength.

5. Protective framework (100) according to one of claims 1 to 4, characterized in that the beam (122, 174) with higher mechanical strength is a reinforced tubular bar.

6. Protective framework (100) according to one of claims 1 to 5, characterized by a safety cable (219, 220, 221) which is arranged largely below the uppermost beam (122, 174) with higher mechanical strength and is fastened to the ends of the uppermost beam (122, 174) with higher mechanical strength and / or is fastened to the supports to which the top beam (122, 174) with higher mechanical strength is fastened.

7. Protective framework (100) according to one of claims 1 to 6, characterized in that the first framework section (202) and the second framework section (204) are arranged such that that the at least one beam (122) with higher mechanical strength of the first framework section (202) and the at least one beam (174) with higher mechanical strength of the second framework section (204) are arranged opposite one another.