The Morgan Draw is a single leaf rolling lift carrying two tracks over the Cheesequake

Transcription

1 MORGAN DRAW ROLLING LIFT TREAD AND TRACK PLATE REPLACEMENT By: Jeffrey D Keyt PE Director of Mechanical Engineering Parsons 100 Broadway New York, NY, Phone: Fax: Number of words: 5079 ABSTRACT: The Morgan Draw is a single leaf rolling lift carrying two tracks over the Cheesequake Creek in Sayreville, NJ. Heavy commuter train traffic traverses the bridge 18 hours per day severely curtailing the duration of full closures, which were necessary to effect repairs to components that support the dead and live loads. The components replaced include the track girder and track, the tread plates, the angles attaching the segmental girders to the tread plates, racks, pinions, pinion shafts and pinion shaft bearings. New tread plates of increased thickness were installed to conform to modern AREMA guidelines. The angles attaching the tread plates to the segmental girders were designed to bear on the tread plates and transmit all loads to the segmental girder webs using a high strength bolted connection. Spherical roller bearings in place of the original solid plain bushings, reduced the friction in the machinery system and allowed the pinion shafts to be aligned to the racks without being constrained by the planes of the

2 structural steel supporting the bearings. Special procedures were required to maintain and improve the alignment of the rolling lift span to the track girder span. Figure 1: Aerial photograph: Elevation of the Morgan Draw. The rolling lift span was opening to allow the waiting marine traffic to pass. BRIDGE DESCRIPTION: The Morgan Draw is located over the Cheesequake Creek in the town of Sayreville, in Middlesex County, New Jersey. The railway is electrified with a catenary system and also carries trains propelled by diesel powered locomotives. The bridge carries the two main line tracks of the New Jersey Transit s North Jersey Coast railway. The bridge

3 was constructed in 1912 and has six spans that vary in length between 21 and 79 feet. The single leaf rolling lift span is 61 feet long. (See Figure 1.) All track on the bridge is on wood ties. Adjacent to the rolling lift span is the track girder span. A number of repairs were performed to the fixed spans and piers however this paper will highlight the repairs performed to the rolling lift and track girder spans. Heavy commuter train traffic traverses the bridge 18 hours per day severely curtailing the duration of full closures, which were necessary to perform repairs to components that support the dead and live loads. The marine traffic is mostly recreational and small fishing boats. The marine traffic is also seasonal with winter being the least active season. The rolling lift span is a through girder open deck configuration with track stringers framed into floor beams which are framed into the bascule girders. The bascule girders are connected to the segmental girders with a complex web splice. The segmental girders connect the bascule girders to the bottom of the counterweight and provide a curved surface that enables the leaf to roll open and closed. The segmental girders resist compressive loads between the bascule girders and the counterweight and bending loads when the leaf is partially open. (See Figure 2.) The track girder span uses the track girders as the main longitudinal girders spanning 21 feet, 4 inches between the bascule pier and an adjacent pier. Two floor beams frame into the bearing stiffeners at the ends of the track girders. The bearing stiffeners also transmit live load from the segmental girders of the rolling lift span to the track span bearings on the bascule pier by being milled to bear at the top and bottom flanges. Four

4 track stringers frame into the two floor beams. The rolling surfaces of the track girder track plates were at approximately the same elevation as the rails. The track girders support the track plates and function in bending as the leaf rolls open and closed. The original segmental and track girders were single web built up from plates and angles fastened together with rivets. Angles forming the top and bottom flanges were located on each side of each girder. Tread plates and track plates were fastened to the flanges of the segmental girder and the track girder using two alternating rows of bolts through each flange on each side of the web of the girder. The original tread plates were 1.75 inches thick. There were teeth that protruded upwards from the edges of the tracks and meshed with pockets in the tread plate. These teeth assured longitudinal and transverse alignment of the rolling lift span and the track girder span. The counterweight was overhead, and the machinery was span mounted over the track girder span and above the railroad clearance envelope. The pinions were cantilever mounted in bronze sleeve bearings at the center of roll which was below the top of the railroad clearance envelope. BRIDGE CONDITION: The primary deficiencies were the cracked and worn tread plates and the attachment of the tread plate to the segmental girder. The tread plate thickness varied and was thinner under the live load bearing stiffener of the segmental girder. The cracked flange angles had been previously reinforced with triangular shaped stiffeners. There were shim plates welded to the tops of the track plates to compensate for the loss of height of the segmental girder. These plates were deformed due to the heavy loads applied. The

5 replacement of the tread plates was necessary due to cracks, wear and varying thickness. (See Figure 3.) The condition of the surface of the segmental girder webs that bear upon the tread plates could not be inspected without removing the tread plates and was therefore not practical. Calculations were performed using AREMA Part b, c, and d to evaluate the thickness of the tread plate in relation to the existing web thickness. These calculations indicated that a tread plate thickness of 4 ½ inches was necessary rather than the existing thickness of 1 3/4 inches. Considering the deformed tread plate and the high bearing stress implied by the calculations relative to the web thickness and the tread plate thickness, the existing segmental girder outside radius bearing surface would not have been of a constant radius or smooth enough to directly bear on the tread plate. Field machining of this surface at a minimum would be required to restore a constant radius and smooth surface. The curved rolling surfaces of rolling lift bridges should form separated sections of one common cylindrical surface. Similarly the track plate rolling surfaces should be coplanar and level. It is straight forward to measure the levelness of the two track plates and determine that they are level and co-planar. Achieving this and measuring the location of the two curved tread surfaces with respect to each other is challenging due to the distance between the two tread plates. This can be accomplished with reference to the center of roll. The center of roll, or centerline of roll, is a transverse line that is the center of the cylinder of the tread plate surface and is also the centerline of the pinion shaft and is

6 referenced to the rolling lift span leaf. The center of roll should move away from the navigation channel in a level plane as the span opens. Also, as the span rolls, the center of roll should remain parallel to the orientation of the center of roll when the span is seated in the fully closed position. Additional deficiencies included misalignment between the rolling lift span and the track girder span. This misalignment caused the rolling lift span to move transversely in one direction as the span opened. This resulted in hard contact and significant wear of the contact surfaces of the teeth and sockets of the tread and track plates that would tend to resist this movement. Additionally as the span moved transversely, the pinions moved with the span, axially in relation to the racks. The pinions became axially misaligned with the racks as the span approached the open position. There was radial misalignment of the racks and pinions due to the decreased thickness of the tread plate and section loss of the segmental girder edge bearing surface. The radial misalignment was severe enough that the backlash was reduced to zero causing interference between the racks and the pinions. The flanks of the racks and pinions had curved grooves on what should have been smooth surfaces. This condition was also present on the top and bottom lands of the pinion and rack, indicating that high loads were being transferred during sliding in the transverse direction. The top and bottom lands of gears are not intended to be contact surfaces. This scenario provided an undesirable alternate path for the dead and live loads from the rolling lift span to the pier. These loads grow progressively larger as the wear increases and overload the gear tooth flanks and the pinion shafts. The visual indications of this were spiral grooves and plastic flow of gear tooth flanks. This is a common deficiency of rolling lift spans.

7 The tread plates were transversely aligned with the track plates at the contact point with the leaf in the lowered position. Plumb bobs hung from the ends of the tread plates nearest the counterweight indicated transverse misalignment between the ends of the treads and tracks when the leaf was lowered. This was consistent with observations during span openings. The pockets on one side of one tread plate were against the teeth of the mating track plate. The webs of the segmental girders were further apart towards the counterweight than towards the navigation channel. When the leaf was rolled halfway open plumb bobs were also hung from the same location and were transversely displaced even further than when the leaf was closed. Measurements of the pinion elevations at various angles of opening were obtained. The elevations varied, indicating that the center of roll was not remaining at a constant elevation as the leaf translated. Either the pinion shafts were bent due to overloading, or the radius from the pinion to the tread plate was not consistent due to deterioration of the segmental girders and tread plates, or a combination of the two. The existing pinions had 14 teeth, a circular pitch of 2 ½ inches and were cantilever supported using flange mounted cylindrical plain bearings. The pressure angle of the existing racks and pinions was 15 degrees and the pinion teeth were thicker than the rack teeth in order to increase the bending strength of the pinion tooth. There was an annular space of greater than inch between the bearing housings and the holes in the webs of the columns that supported the pinions. The original plans called out tightfitting holes but the pinion bearings and pinion shafts had been replaced. Fretting corrosion was observed between the bearing housing and the web of the verticals. The bushings were not protruding from the bearing housings which has been a common

8 inspection finding on many rolling lifts. This was most likely because the bearings were not original. The most significant prior repair was the replacement of the track plates in The original track plates were removed and thicker track plates were installed on top of the original track girders. The thicker track plates were 4 ½ inches thick, which was sufficient to satisfy the current AREMA guidelines. This raised the rolling lift span 2 ¾ inches requiring the rails on the rolling lift span to be aligned vertically with the rails on the other spans. The elevations of the pinions also rose by the same amount which required additional shims under the racks to maintain the radial alignment between the racks and pinions. PROJECT OBJECTIVE: The goals of this rehabilitation project were as follows: Provide a durable repair to the tread plate, track plate and segmental girder. Replace the racks and pinions, pinion shafts and bearings. Accommodate or correct if possible, existing misalignments and install new components in proper relation to existing components, in order to assure proper operation of the rolling lift span and avoid damage and wear. Design the repairs and establish an installation sequence so that the work could be broken down into small tasks which could be performed in short periods of time. Schedule construction operations so that both rail tracks were open during weekday morning and evening rushes and one track was open at other times. Also both tracks

9 were to be available in early morning hours and on two weekends with advanced scheduling. A permit was obtained from the USCG that allowed the rolling lift span to be inoperable January 1st 2008 through March 31st REHABILITATION OF THE SEGMENTAL GIRDER: While the tread plates and flange angles seemed to have had the most significant defects, replacing the tread plates and flange angles alone would have only temporarily ameliorated symptoms of other problems. It would have been very difficult to install new tread plates and obtain consistent bearing with the edges of the segmental girders without field machining. A durable repair could be achieved by replacing the flange angles and restoring the segmental girder web bearing surfaces, or by replacing both the bearing surfaces and flange angles. Replacing the tread plate with a thicker tread plate was desirable but is a more complicated rehabilitation because a thicker tread plate attached to the existing girder has a larger outside radius. The larger outside radius would raise the span and pinion further and cause the span to move further away from the navigation channel as it rolls open. This is a likely reason that the tread plates were not replaced during the rehabilitation work in To avoid these complications a repair scheme was considered and selected where the tread plate outside radius was maintained at the original value of 14 feet 6 inches and the inside radius was decreased to allow a thicker tread plate that conformed to AREMA guidelines. This necessitated reducing the outside radius of the segmental girder web

10 by cutting it in the field. To avoid time consuming and costly field machining to precise dimensions, the original webs were cut to a radius one quarter inch smaller than the new tread plate inside radius. This avoided the need for precision because the webs do not bear on the tread plates. The void created was filled with a polyurethane elastomeric sealant. In the existing configuration the web, side plates and vertical legs of the angles were in bearing on the tread plate and were capable of transferring load between the tread plate and the segmental girder web. Calculations using AREMA Part c, and d were performed to determine the participation of fasteners in transferring the loads into the segmental girder webs. The loads were transferred between the existing angles and existing side plates with four rows of rivets arranged in arcs of different radii. The web was cut to reduce its outside radius in order to provide space for a thicker tread plate. This resulted in the loss of the row of transverse web fasteners with the arc of the greatest radius. This row of fasteners offers a lesser contribution to the connection capacity than the rows with a lesser radius due to a fewer number of effective fasteners. In fact, only three fasteners at a time from this row, contribute to the calculation. To compensate for the loss of this row and reduction in fasteners, four additional rows of bolts were provided with a shorter radius from the center of roll to the arc of these rows of bolts than to the row of existing rivets with the shortest radius. Smaller diameter bolts were used due to smaller bolt spacing. Eight bolts in the added row with the greatest radius are effective in the calculation at any one time. The existing angles and existing side plates were removed and discarded. These were replaced by one piece angle weldments; One angle weldment was installed on each

11 side of the segmental girder web. The new angle weldments transfer all of the dead load from the tread plate through bearing on the tread plate and through a friction bolted connection to segmental girder web. The new angle weldments were fabricated as follows: A curved plate with a radius matching the inside radius of the new tread plates was used to form the outstanding leg of the new angle weldment. This curved plate was welded with a complete joint penetration (CJP), to a flat plate with a curved edge with the same radius. This flat plate becomes the upstanding leg of the angle weldment. After stress relief the flat plate was machined to create a flat surface to bear against the web and to create a reference surface for additional machining. The flat surfaces of the two angle weldments for one segmental girder were placed against each other in the orientation in which they were to be installed. Alignment holes were located and drilled in the webs. Pins that fit tightly in the holes were inserted into the holes. Then the curved surfaces of both angle weldments were machined in the same operation to provide a smooth surface and a precise radius to bear on the tread plate. The flat legs of the angle weldments were bolted to the segmental girder. The thickness of these flat upstanding legs was chosen so that together these two plates satisfy the AREMA c and d guidelines for the thickness of the segmental girder web bearing surface. (See Figure 4.) In order to ensure that the two angle weldments on each segmental girder were aligned with each other and to the pair on the other segmental girder, the Contractor was required to fabricate and use radial and chordal templates to locate alignment holes in the segmental girder webs. These holes were located and drilled in the segmental girder webs at a precise distance from the center of roll, a vertical line through the

12 center of roll, and each other. The locations of these alignment holes also matched the location of previously drilled alignment holes in the angle weldments. All of these alignment holes were drilled to a size that would be tight fitting around pins that would be inserted in them. (See Figures 5 and 6.) Stiffeners were provided at the location of the tread plate joint to transfer the load into the web with additional fasteners. Due to the discontinuity of the tread plate and side plate at this location half of the web fasteners can be ineffective when the contact point on the tread is near the tread plate joint. Bearing stiffeners were provided to transfer live load at the location of the tread to track contact point with the span fully lowered. TRACK AND TRACK GIRDER REPLACEMENT: The existing track teeth were cast integral with the track. A forged rather than a cast material was preferred for the replacement track. Fabricating a replacement track from a forging would require starting with a plate that was thicker by one and one half inches and machining that thickness away everywhere except where the teeth were to be located. An alternative to integral teeth was to provide separate teeth attached to the track and track girder flange with bolts. The separate teeth offered numerous advantages. The initial thickness of the track plate forging was reduced and the quantity of material removed by milling was reduced. The tread and track plates could be moved in the bridge longitudinal direction with the teeth removed facilitating installation. Transverse adjustment of the apparent track position after final positioning of the track girder could be accomplished with differently sized teeth. During the service life of the structure, worn or broken teeth could be replaced. The track was provided as a forging

13 with separate track teeth that were attached with two bolts in line with the longitudinal row of bolts that connect the track plate to the track girder. The teeth fit into the track with a locational tolerance fit. Details for teeth with larger and smaller transverse dimensions were provided on the contract drawings in order to provide an additional method of adjustment. It was not necessary to utilize this method of adjustment at the time of construction. The spacing and locations of the track teeth and pockets in the tread plate were kept the same as the existing so that the construction sequence would allow the new tread plates to roll on the existing track girders or vice versa. There was one bolt in each tread plate pocket in line with the longitudinal row of bolts that connected the tread plate to the angle weldment. New track girders were provided with a top flange that was machined to provide a flat smooth surface for bearing with the track plate. During installation the track girders were to be aligned to the apparent path of the segmental girder tread as the leaf opens to compensate for the lack of parallelism of the segmental girder webs. REPLACEMENT OF RACK AND PINION SHAFT AND BEARING: Replacement of the pinion bearings with flange mounted spherical roller bearings provided the self-aligning capability between each pinion bearing and the mounting structural steel. This self-aligning capability functions to compensate for the lack of precise parallelism of structural members under no load but also deflection of those members when the pinion shaft applies load to the members. The pinion shaft rotates more than three times during a normal opening which is more than sufficient to avoid

14 only loading a portion of the races and rollers. An additional benefit of the roller bearings is reduced friction. The starting coefficient of friction of the cylindrical bearings is 0.18 compared to of the spherical roller bearings. This reduction in friction allows a greater percentage of the torque delivered to the input of the pinion shaft to be used to move the rolling lift span. The modern AREMA guidelines recommend that the minimum number of teeth on any gear be 17. The practical advantages of 17 teeth or greater include greater allowable tooth load compared to fewer teeth with constant circular pitch and avoidance of undercutting the roots of the gear teeth to prevent interference between the tips and roots. An increase in the number of teeth while maintaining the same circular pitch will increase the pitch diameter of the gear. The ratio of the pinion and rack is effectively the tread plate radius divided by the pinion radius. As the pinion radius increases due to increasing the number of teeth, the torque available to operate the bridge decreases. Also the force required to create the torque to move the bridge increases as the pinion pitch radius increases, which must be compensated for by increasing the available torque. Additionally the rack must be lowered to compensate for the increased pinion pitch diameter. A large increase would require lowering or replacing the rack support, increasing the number of tasks that must be completed in the critical time periods. In order to avoid altering the ratio the circular pitch of the rack and pinion can be decreased to minimize the increase in pitch diameter of the pinion. However as the circular pitch decreases, the allowable tooth load decreases necessitating a greater face width or stronger material. The face width that is allowed to be used to calculate

15 the strength can be no greater than three times the circular pitch which actually required a slight reduction compared to the existing teeth. The replacement rack and pinion had a circular pitch of inches and a more modern pressure angle of 20 degrees. The increase in available torque due to the antifriction bearings was used to compensate for the effect of the increase in the pinion radius reducing the torque. A balance was achieved by selecting a pitch diameter and resulting ratio that delivered a torque reduction that was less than the torque increase provided by the switch to antifriction bearings. The material selected for the pinion was an alloy steel that suitably compensated for the smaller size of the gear teeth. The actual selection was based on the motor and brake torques, intermediate gearing ratios and losses. SEQUENCE AND SCHEDULE: To achieve the aforementioned alignment goals a detailed set of procedures was developed and executed in the following sequence: 1. Level the rolling lift span in both the longitudinal and transverse directions by shimming at the tread contact point and at the live load bearings at the toe. 2. Remove the pinion shafts and bearings, determine the center of roll and line bore the pinion bearing holes. 3. Install the new pinion bearings and pinion shafts. 4. Measure the position of all webs relative to the center of roll. Locate and drill reference holes in the segmental girders using radial and chordal templates.

16 5. Locate and drill reference holes in the angle weldments and machine the curved surfaces with respect to those holes. 6. Replace the rivets in the segmental girder with temporary bolts. 7. Remove the tread plates, temporary bolts, angles and side plates. 8. Remove the track girders with track plates. 9. Install the angle weldments and tread plates and align with pins. 10. Drill new holes and ream existing holes in the segmental girder webs and install permanent bolts. 11. Install the track girders with track plates and align to the segmental girders. 12. Install the track plate teeth. 13. Install the new racks and pinions and align the rack segments to the pinions. The most demanding field work was planned to occur during a three month closure of the navigation channel during January February and March. During this time period the span did not have to be opened for marine traffic and could be immobilized and disassembled once alternate load paths were established with temporary supports. (See Figures 7 through 10.) In order to replace the tread plate and the track plate and girder, the leaf was supported by an alternate means in a manner that transmitted the dead and live loads to the pier as well. A jacking system was developed that lifted the span and lowered it onto temporary supports on the end of the track girder at the location of the heel of the leaf. (See Figure 11.) Also a support for the counterweight, near the end of the track girder furthest from the navigation channel was necessary to remove the load from the segmental girder while the side plates and angles were removed. While the leaf was

17 lifted and supported by the jacks, the track girders were removed and replaced. The bridge was closed to rail traffic during this phase and it was accomplished during a weekend closure. While the leaf and counterweight were supported on the temporary supports, the bridge was available to rail traffic and the tread plates were removed, the segmental girders were disassembled and the new angle weldments and tread plates were installed. CONCLUSION: The components replaced included the track girder and track, the tread plates, the side plates and the flange angles attaching the segmental girders to the tread plates, the racks, pinions, pinion shafts and pinion shaft bearings. The thickness of the tread plates was increased to conform to modern AREMA guidelines. The angle weldments attaching the tread plates to the segmental girders were designed to bear on the tread plates and transmit all loads to the segmental webs using a high strength bolted connection. Spherical roller bearings in place of the original solid plain bushings reduced the friction in the machinery system and allowed the pinion shafts to be aligned to the centerline of roll and to the racks without being constrained by the planes of the structural steel supporting the bearings. Alignment procedures were required to maintain and improve the alignment of the rolling lift span to the track girder span. The span was returned to service with all repaired and replaced components suitable for a long life. The rail traffic was not disrupted other than what was allowed by the Contract. The leaf was operable by March 31, 2008 and marine traffic was not interrupted beyond what was allowed by the Coast Guard permit.

18 ACKNOWLEDGEMENTS: Owner: New Jersey Transit Director of Infrastructure Design - James Galvin PE Contractor: Kiska Construction Designer: Parsons FIGURES: Figure 1: Aerial photograph: Elevation of the Morgan Draw Figure 2: Photograph: Elevation of the segmental girder Figure 3: Photograph: View of tread plate and track plate contact point Figure 4: Cross sections of existing and new segmental girder configurations Figure 5: View of segmental girder in existing configuration Figure 6: View of segmental girder shown after rehabilitation Figure 7: Construction sequence: Phases I and II Figure 8: Construction sequence: Phases III and IV Figure 9: Construction sequence: Phases V and VI Figure 10: Construction sequence: Phases VII and VIII Figure 11: Rolling lift span jacking system

19 Figure 2: Photograph: Elevation of the segmental girder. Additional stiffeners that had been welded to the flange angle were visible. The longer riveted stiffeners were original.

20 Figure 3: Photograph: View of tread plate and track plate contact point. The tread plate had reduced thickness at the contact point and was cracked.

21 Figure 4: Cross sections of existing and new segmental girder configurations. Cross section of existing segmental girder web, side plates, flange angles and tread plate shown on left. Cross section of new angle weldments and tread plate with existing web shown on right.

22 Figure 5: View of segmental girder in existing configuration. There were four rows of rivets through the side plates. The templates were used to align the new angle weldments to the center of roll.

23 Figure 6: View of segmental girder shown after rehabilitation. There are seven rows of high strength bolts through the angle weldments. The three rows of bolts closest to the tread plate pass through existing rivet holes for the existing side plates that have been removed.

24 Figure 7: Construction sequence: Phases I and II

25 Figure 8: Construction sequence: Phases III and IV

26 Figure 9: Construction sequence: Phases V and VI

27 Figure 10: Construction sequence: Phases VII and VIII

28 Figure 11: Rolling lift span jacking system: The bascule girder is shown to the left of the jack and the track girder is shown to the right. The jack was located under the splice between the bascule girder and the segmental girder. The temporary support for the rolling lift span was through the track girder to the grillage to the pier.

29 2012 Annual Conference & Exposition MORGAN DRAW ROLLING LIFT TREAD AND TRACK PLATE Jeffrey D Keyt PE Director of Mechanical Engineering PARSONS 100 Broadway New York, NY, 10005

30 2012 Annual Conference & Exposition MORGAN DRAW

31 2012 Annual Conference & Exposition MORGAN DRAW ELEVATION Three through girder spans Rolling Lift Span Track Girder Span Track Stringer Span provide clearance for counterweight as the leaf rolls open

32 2012 Annual Conference & Exposition ROLLING LIFT AND TRACK GIRDER SPANS - ELEVATION

33 2012 Annual Conference & Exposition ROLLING LIFT AND TRACK GIRDER SPANS - FRAMING PLAN LEFT Rolling lift span RIGHT Track Girder Span

34 2012 Annual Conference & Exposition SEGMENTAL GIRDER - VIEW

35 2012 Annual Conference & Exposition SEGMENTAL GIRDER - FUNCTIONS Provides curved surface for rolling Supports leaf dead load Acts in Bending

36 2012 Annual Conference & Exposition DEFFICIENCIES Track plate misaligned, not level Tread Plate Cracks, loss of thickness Segmental Girder - loss of web bearing, cracked flange angles Rack and pinion - misalignment, worn surfaces Span Misalignment

37 2012 Annual Conference & Exposition TREAD PLATE CONDITION Cracks Loss of section due to repeated high loads and corrosion Insufficient thickness for loads applied

38 2012 Annual Conference & Exposition TREAD PLATE CONDITION Wear Loss of thickness

39 Deformed and cracked flange angles SEGMENTAL GIRDER Stiffeners added to mitigate crack Loss of web bearing surface Reduced height from track to pinion 2012 Annual Conference & Exposition

40 2012 Annual Conference & Exposition TRACK PLATE CONDITION Thickness 4 ½ inches ¼ inch Plates added

41 2012 Annual Conference & Exposition TRACK AND TRACK GIRDER Track surface and top flange not level

42 2012 Annual Conference & Exposition PINION AND PINION BEARING Fretting corrosion at bearing flange Axial misalignment varied as leaf rolled

43 2012 Annual Conference & Exposition PINION AND PINION BEARING Pinion elevation varied as leaf opened Spiral grooves Clearance in pinion bearing mounting holes

44 2012 Annual Conference & Exposition RACK CONDITION Spiral Grooves on Tooth flanks Evidence of contact on top and bottom lands

45 2012 Annual Conference & Exposition TREAD AND TRACK ALIGNMENT Plumb bob hung from center of track near the counterweight

46 2012 Annual Conference & Exposition TREAD AND TRACK ALIGNMENT Plumb bob lands 2 ¼ inches from the track center

47 2012 Annual Conference & Exposition PROJECT OBJECTIVES Correct Track plate alignment and levelness Install thicker Tread Plates Insure alignment of Segmental Girders and tread plates Replace rack and pinion Improve Span alignment Replace track and track girder

48 2012 Annual Conference & Exposition PROJECT OBJECTIVES Maintain railroad traffic except for weekend closures Accomplish work during three month winter closure of the navigation channel

49 2012 Annual Conference & Exposition SEGMENTAL GIRDER AND TREAD PLATE IMPROVEMENTS Tread plate 4 ½ inches thick New angle weldments Machined cylindrical surfaces on tread plates and angle weldments Seven rows of bolts

50 2012 Annual Conference & Exposition SEGMENTAL GIRDER AND TREAD PLATE CROSS SECTION Before After

51 2012 Annual Conference & Exposition SEGMENTAL GIRDER ALIGNMENT Locate center of roll on both girders Line bore pinion mounting holes Radial and chordal templates Alignment holes

52 Top flange reinforced New angle weldments aligned to the center of roll with alignment holes and templates 2012 Annual Conference & Exposition SEGMENTAL GIRDER RECONSTRUCTION

53 2012 Annual Conference & Exposition CONSTRUCTION SEQUENCE I AND II Reinforce segmental girders Remove existing and install new track plates and girders Secure leaf at toe

54 2012 Annual Conference & Exposition CONSTRUCTION SEQUENCE III AND IV Install jacking column at counterweight Remove rivets in side plates and install temporary high strength bolts

55 2012 Annual Conference & Exposition CONSTRUCTION SEQUENCE V AND VI Disassemble segmental girder webs, side plates Install new angle weldments Remove support column at counterweight

56 2012 Annual Conference & Exposition CONSTRUCTION SEQUENCE VII AND VIII Install new tread plate lower segments Install new tread plate upper segments

57 SPAN JACKING Bascule girder-left Segmental girderright New stiffening bearing splice plates Jack under splice Fixed Bearing on reinforced track girder web 2012 Annual Conference & Exposition

58 ACKNOWLEGEMENTS 2012 Annual Conference & Exposition Owner: Contractor: Designer: NJ Transit KISKA Construction PARSONS