MORGAN DRAW ROLLINGLIFT TREAD AND TRACK ......MORGAN"DRAW"ROLLING"LIFT"TREAD...

MORGAN DRAW ROLLING LIFT TREAD AND TRACK PLATE REPLACEMENT

By: Jeffrey D Keyt PE

Director of Mechanical Engineering

Parsons

100 Broadway New York, NY, 10005

Phone: 212 266 8487 Fax: 212 571 6824

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

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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

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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

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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

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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 6.5.35.5 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

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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.

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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 0.025 inch between the bearing housings and the holes in

the webs of the columns that supported the pinions. The original plans called out tight-

fitting 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

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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 1984. 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

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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 2008.

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 1984.

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

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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 6.5.35.5 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

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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 6.5.35.5 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

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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

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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

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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 0.004 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 under-

cutting 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

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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 2.125 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.

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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

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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.

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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

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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.

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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.

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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.

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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.

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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.

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Figure 7: Construction sequence: Phases I and II

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Figure 8: Construction sequence: Phases III and IV

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Figure 9: Construction sequence: Phases V and VI

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Figure 10: Construction sequence: Phases VII and VIII

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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.

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September 16-19, 2012 Chicago, IL

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

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MORGAN DRAW

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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

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ROLLING LIFT AND TRACK GIRDER SPANS - ELEVATION

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ROLLING LIFT AND TRACK GIRDER SPANS - FRAMING PLAN

•  LEFT Rolling lift span RIGHT Track Girder Span

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SEGMENTAL GIRDER - VIEW

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SEGMENTAL GIRDER - FUNCTIONS

•  Provides curved surface for rolling

•  Supports leaf dead load

•  Acts in Bending

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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

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TREAD PLATE CONDITION

•  Cracks •  Loss of section

due to repeated high loads and corrosion

•  Insufficient thickness for loads applied

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TREAD PLATE CONDITION

•  Wear •  Loss of thickness

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SEGMENTAL GIRDER

•  Deformed and cracked flange angles

•  Stiffeners added to mitigate crack

•  Loss of web bearing surface

•  Reduced height from track to pinion

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TRACK PLATE CONDITION

•  Thickness 4 ½ inches

•  ¼ inch Plates added

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TRACK AND TRACK GIRDER •  Track surface and top flange not

level

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PINION AND PINION BEARING •  Fretting corrosion at bearing flange •  Axial misalignment – varied as leaf

rolled

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PINION AND PINION BEARING

•  Pinion elevation varied as leaf opened

•  Spiral grooves •  Clearance in

pinion bearing mounting holes

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RACK CONDITION

•  Spiral Grooves on Tooth flanks

•  Evidence of contact on top and bottom lands

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TREAD AND TRACK ALIGNMENT

•  Plumb bob hung from center of track near the counterweight

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TREAD AND TRACK ALIGNMENT •  Plumb bob lands 2 ¼ inches from

the track center

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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

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PROJECT OBJECTIVES

•  Maintain railroad traffic except for weekend closures

•  Accomplish work during three month winter closure of the navigation channel

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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

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SEGMENTAL GIRDER AND TREAD PLATE CROSS SECTION

•  Before After

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SEGMENTAL GIRDER ALIGNMENT •  Locate center

of roll on both girders

•  Line bore pinion mounting holes

•  Radial and chordal templates

•  Alignment holes

© 2012 AREMA



SEGMENTAL GIRDER RECONSTRUCTION

•  Top flange reinforced

•  New angle weldments aligned to the center of roll with alignment holes and templates

© 2012 AREMA



CONSTRUCTION SEQUENCE I AND II •  Reinforce

segmental girders

•  Remove existing and install new track plates and girders

•  Secure leaf at toe

© 2012 AREMA



CONSTRUCTION SEQUENCE III AND IV

•  Install jacking column at counterweight

•  Remove rivets in side plates and install temporary high strength bolts

© 2012 AREMA



CONSTRUCTION SEQUENCE V AND VI

•  Disassemble segmental girder webs, side plates

•  Install new angle weldments

•  Remove support column at counterweight

© 2012 AREMA



CONSTRUCTION SEQUENCE VII AND VIII •  Install new

tread plate lower segments

•  Install new tread plate upper segments

© 2012 AREMA



SPAN JACKING •  Bascule girder-Left

Segmental girder-right

•  New stiffening bearing splice plates

•  Jack under splice •  Fixed Bearing on

reinforced track girder web

© 2012 AREMA



ACKNOWLEGEMENTS

Owner: NJ Transit Contractor: KISKA Construction Designer: PARSONS

© 2012 AREMA

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