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Title CP Rejuvenates Century Old River Bridge on Important Coal Route Authors Mordechai Ludmer, P. Eng Kristi Morgan, E.I.T. Railway Project Engineer Project Manager Stantec Consulting Services, Inc. Canadian Pacific Railway 110-100 Alexis-Nihon Boulevard Building #1, 7550 Ogden Dale Road SE Saint-Laurent, QC H4M 2N6 Calgary, AB T2C 4X9 Office: +1 (514) 340-2155 Office: +1 (403) 319-7498 Mordechai.Ludmer@stantec.com Kristi_Morgan@cpr.ca Richard Lanyi, P. Eng Railway Practice Lead Stantec Consulting Services, Inc. 10160 – 112 Street Edmonton, AB T5K 2L6 Office: +1 (780) 917-7119 Richard.Lanyi@stantec.com Number of Words MS – Word Count: 4,235 Number of Pictures: 8 @ 250 words per picture = 2,000 words Total Word Count: 6,235 Table of Contents Abstract  Introduction Existing Conditions Bridge Replacement verses Rehabilitation Evaluation Bridge Span Replacement Options Analysis Span Replacement Stabilization of both abutments with soil anchor tie back systems Jacketing of Piers and Abutments Conclusion

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Figure 1 - Berm Plan Figure 2 - Typical Section Figure 3 - Gantry Crane Positioned For First Lift Figure 4 - New TPG Temporarily Seated Next To The 1913 HDPG Until The Next Track Block Figure 5 - Bridge Girder Removed From Span 8 Figure 6 - Existing Span Removal: South Elevation View ABSTRACT Renewal of an in-service, single track, eight span, 100-year-old railway bridge is not an easy task for any Railroad, especially when that bridge crosses the powerful Kootenay River and carries 160 car unit coal trains with up to 20 trains a day. Constructed in 1913, this bridge consists of eight open deck steel half deck plate girder (HDPG) spans and forms part of CP Rail’s Coal Route between Sparwood and Golden, in Southeastern British Columbia. From Golden, coal trains connect to CP’s mainline heading westbound to the Port of Vancouver. This project was the crowning achievement on what has been a multi-year initiative to upgrade infrastructure and capacity along this 260-mile corridor through the Columbia and Kootenay River valleys. With train volumes expected to increase and operating speeds of 35 MPH over the bridge, safety was of utmost concern. Developing work plans and span replacement schemes which minimized the impact to CP’s normal operations as well as construction activities was the greatest challenge. Two schemes were developed and evaluated, one involving river berms and conventional crane installation, the other involving innovative overhead gantry systems with roll-in/roll-out installation schemes. This paper will discuss each option and the decision making process leading to the selection of the overhead gantry system. It will also discuss other significant project aspects involving design of the new open deck steel TPG spans, stabilization of both abutments with soil anchor tie back systems, and the jacketing of all seven of the existing concrete piers. Overall schedule and cost information will also be presented. INTRODUCTION Bridge 14.58 on CP’s Windermere Subdivision consists of 8 – 75 foot steel spans crossing the Kootenay River in southeastern British Columbia (BC), Canada. The Windermere Subdivision is a major component of CP’s BC Coal Route linking the coal mines of southeastern BC to Golden, BC; CP’s terminal along their east/west mainline providing coal service to major international ports on Canada’s west coast. Coal trains consist of up to 120 – 286 kip capacity cars. The Windermere Subdivision carries between 15 to 18 trains per day, with 10 to 12 consisting of heavy coal traffic. The original bridge was constructed in 1913, over 100 years ago. The superstructure consists of 8 identical 75 foot HDPG open deck steel spans designed to Cooper E50 live load. Spans are supported on 2 cast in place concrete abutments and 7 concrete piers; all founded on 12” diameter (nominal) timber piles. Abutments are over 30 feet in depth from underside of concrete to top of backwall. Original fixed bearings consisted of steel pedestals and expansion bearings consisted of steel roller nests. The Kootenay River is a major watercourse flowing through southeast BC. It is over 600 feet wide in the vicinity of this bridge. At low water levels, water flows below only 5 of the existing 8 spans. High water can over top the existing banks of the river. In 2013, one year before this bridge replacement commenced, an extreme flood event occurred with water rising to just inches below the bottom flange of the steel spans. Highest water typically occurs between the months of May and July as a result of a combination of snow melt in the nearby Rocky Mountains, and heavy spring rainfalls. EXISTING CONDITIONS HDPG steel spans involve the support of deep 16” to 18” timber ties supported on continuous steel shelf angles riveted (or bolted from repairs) to the webs of the 2 main steel girders. These spans may generate longitudinal cracks in the webs of the girders, along the length of these shelf angles, due to localized corrosion, section loss and flexing of the web plates under live load. The steel spans of Br.

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14.58 Windermere were no exception to this problem. Further, the existing deep timber ties were experiencing a fair amount of longitudinal splitting due to the heavy cyclical loading for the relatively long 13 foot span between girders. To temporarily mitigate these problems, CP had installed vertical timber blocking between the underside of the bridge tie ends and the top of the girder bottom flanges, at both ends, for all ties in all spans. Additionally, blocking between ties was also installed to prevent the bridge ties from moving longitudinally under load. Pending superstructure replacement, attempts had been made to repair split ties with bolting and tie filling compound. Prior to span replacement, the bridge had a slow order of 30 MPH to reduce impact loading on the steel spans and provide safe passage of trains. Both concrete abutments had rotated forward about their piled bases causing them to lean against the top flanges of the girder ends. Over time, these end spans have translated horizontally to impact the adjacent spans and to eliminate the potential movement due to thermal expansion and contraction. Attempts had been made to chip away at the backwalls; however, further movements just closed these gaps as well. The existing concrete piers were in relatively good to fair condition, with some evidence of minor cracking and areas of scaling near water level, and closer to pier tops due to the collection of moisture. BRIDGE REPLACEMENT VERSUS REHABILITATION EVALUATION The need for higher speed to accommodate the growing coal business in BC, and the need to replace the existing steel spans which had reached the end of their service life, compelled CP to commission a study to evaluate the options of rehabilitating and replacing the existing bridge. The study was completed by AECOM in 2011. Replacement options investigated options to rebuild the bridge on an adjacent alignment, as well as, along the existing alignment. This would include new substructures and superstructure. Rehabilitation options involved replacing all steel spans, stabilizing the existing tilted abutments and jacketing all existing piers and abutments. They also included an evaluation of the condition of the existing substructures and foundations to perform for an extended period of time beyond their originally anticipated 100-year design life. Both replacement and rehabilitation options considered ballasted and open deck span configurations. In 2012, CP decided to move forward with a span replacement and bridge rehabilitation plan involving reuse of the existing substructures and foundations. This decision was based on the following:

Overall project economics Avoiding impact to natural environment Reduced construction timelines Not having to realign the track for a full replacement option or a new highway crossing Favorable results of their analysis of the existing substructures and foundations to handle an

extended service life

As such, this project included the following components:

Replacement of the existing HDPG open deck steel spans with open deck TPG spans, including new bearings

Stabilization of both abutments with a soil anchor tie back system Jacketing of all piers and abutments Modifications to abutments and approaches to accommodate walkways on both sides of the track New riprap scour protection on all substructures

CP completed the design of the new spans, new spherical bearings and substructure jackets in house. Stantec Consulting Ltd. completed the remainder of the design, including the preparation of tender documents, and construction administration and supervision services.

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BRIDGE SPAN REPLACEMENT OPTIONS ANALYSIS Two options for removal and replacement of these 8 spans were evaluated, they included:

A. Construction of a berm in the Kootenay river for the use of conventional heavy lift cranes B. Launching techniques from track level using an overhead gantry system

Evaluation criteria for selection included the following:

Impact to train operations – maximum available work block was 8 hours Risk to operations and construction Cost Schedule

RIVER BERM AND CRANES Stantec completed a bathymetric survey of the Kootenay River upstream and downstream of the bridge. From this and existing river data, Stantec completed a hydrotechnical evaluation for the construction of a river berm, as well as for the design of riprap scour protection of the substructures. Regarding berm construction, Stantec defined the requirements for berm material, the size of the edge scour protection and the extent of berm to maximize span replacement efficiency. To satisfy local regulators, berm material was defined as existing riverbed materials CP had been stockpiling from channel management operations in the vicinity of the project. The construction window for low water was defined from September to April. During this period, a berm could be constructed across 6 of the 8 spans, high enough to provide 1.5 meters of freeboard. The berm would be wide enough to hold delivery of the new spans, which would be offloaded by a crane off flatcars from the existing bridge deck. It would also hold room for placement of the old spans, as well as a clear runway for the movement of the berm crane. For replacement of the end span over water, a lighter crane would be required on the bank adjacent to the abutment with support from the berm crane.It was conservatively estimated that only 2 spans would be replaced within an 8-hour workblock, therefore a maximum of 4 workblocks would be required. These workblocks would allow for removal of old spans and bearings, preparation of the concrete bearing seats to receive new bearings, installation of the new spans, and installation of the track.

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Figure 1 - Berm Plan

SPAN LAUNCHING Similar span replacement by span launching projects had recently been completed in Canada under similar working restrictions. The ability to reduce risk by staying out of the river was one of the main advantages of this approach. It involved the staging of new spans stored at the Wasa Siding, about 3 miles south of the bridge. New spans would be loaded onto double axle “buggies” fabricated exclusively for this type of work. One buggy was placed at each end of the new span. The new spans were then pulled to the bridge, along with the overhead gantry truss and empty buggies for the removal of the old spans. The gantry truss was long enough to support the existing or replacement spans and allow for placement of end supports on the existing adjacent girders. The gantry would remove the old span and place it on the empty buggies, then place the new span (with bearings attached). The old spans would be transported back to the Wasa siding where they would be dismantled, loaded on an empty flatcars and removed from the site to be sold for scrap metal. These workblocks were conservatively estimated to involve the replacement of one span per block, resulting in the need for 8 workblocks overall.

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SPAN INSTALLATION EVALUATION Both span installations involved the pre-decking of the spans prior to installation with the ties and rail. Tenders were initially let in October 2012. Two issues arose which both involved scheduling concerns. First, it became apparent that a quick award would be required in order to get a contractor mobilized as soon as possible to get the berm constructed allowing enough time for replacement of all spans prior to the end of March 2013, otherwise the berm option would have to wait until September 2013 to begin once the water level subsided. Second, fabrication of the eight new spans was beginning to fall behind and delivery schedules were being pushed back, also jeopardizing the early installation of new spans. When the tender closed the launching option came in at a higher price and a December 2013 completion date. The window of opportunity for an early berm construction was fairly narrow, and it would also require the balance of the year to complete. Upon careful evaluation, CP decided to select the launching option for the following reasons:

It avoided the risks of working in the river and the unpredictability of fluctuating water levels The additional cost was considered insurance against the river work risks Delays in span delivery would not impact the overall project There was no schedule advantage in going with the berm option

SPAN REPLACEMENT Discussion and planning for the launch began in Barrie, Ontario at the headquarters of Western Mechanical in June 2013. Western Mechanical designed, built and customized the gantry crane for this project. Engineered drawings for all components of the lifting system were approved by the General Contractor, the Owner’s Engineer (Stantec) and CP. Particular attention was given to the connections between the gantry crane and the existing bridge girders. High strength steel clamps were used to lock down the gantry to the bridge girders as a precautionary measure. The existing HDPGs and the new TPGs were also temporarily strengthened for installation with Douglas fir timbers, which were forced into position between the top and bottom flanges, both on the outside and inside of the webs at the location where gantry legs would be resting. The meeting in Barrie was an opportunity to plan out the task of changing out a 180 000 lbs. steel bridge in less than 8 hours. Furthermore, this same task needed to be repeated 8 times without fail. The existing bridge piers and abutments had settled differentially over the past 100 years. CP records indicate the majority of this settlement occurred shortly after construction. Given the fact that the bridge was open deck, the top of rail elevation was directly related to the bearing height on the piers and abutments. The size of shims were specified on the construction drawings for every bearing under every bridge span. However, the quality of the bearing seat on the existing piers and abutments was unknown. After 100 years, it was anticipated that the concrete on the bearing seat would be in a fair to poor condition. Provisions were made to remove unsound concrete from the existing bearing seat and replace it with a fast setting, self levelling grout during the work block.

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Figure 2 - Typical Section

The existing spans had moved and shifted by several inches over the course of 100 years. Eight (8) inch gaps between spans as specified on the As-Built from 1913 had been reduced to 1 to 3 inches due to inward rotation of the abutments. This posed an additional challenge for the replacement of the girders. The specified gaps between new girders could not necessarily be achieved with only one lift per span; temporary positions for the first few spans were planned for in order to ensure that all spans would fit across the 600 ft. crossing. Sequencing plans were scrutinized and all dimensions validated on site. In the final weeks before the launch, it was concluded that one lift per span would be sufficient. The gantry crane arrived at the siding in Wasa, BC by rail 1 week before the first launch. The Wasa siding and back track were used as the staging area, located 3 miles from the bridge site. In preparation for the launch, a 4 hour work block was granted to complete a trial run. The gantry crane was loaded onto the tracks by self-propelled heavy duty trailers. The gantry procession then travelled from the staging area to the bridge site where the gantry was set in position for the first lift. The procession then backed up to the staging area and cleared the tracks. The trial run was a success. The only adjustment required before the launch was a correction of the level crossing access ramp slopes at the staging area at the Wasa siding. This was to improve the maneuvering ability of the self-propelled trailers when loading the gantry crane on and off the tracks. The first launch was originally scheduled for September 20th, 2013 but had to be cancelled to accommodate railway operations at the last minute. The first launch was rescheduled to October 4th. The delay was well utilized enabling additional preparation to be completed including installing lifting lugs onto

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both the old and new spans, placing temporary stiffeners on the old and new bridge girders, installing rails on all 8 new spans, installing suspended scaffolding from the piers and placing the new TPG’s on concrete blocks to ensure the self-propelled trailers could load them onto the tracks as quickly as possible. The plan was to remove and replace one span during one 8-hour work block.

Figure 3 - Gantry Crane Positioned For First Lift

At 14h00 on October 4th, after the last northbound train cleared, two buggies were lowered onto the tracks with forklifts and span 1 was loaded onto the tracks and cinched down to the buggies. A 10-ton Hi rail boom truck was backed down the tracks from the bridge and hitched to span 1. The gantry crane was loaded onto the tracks and a track mobile was railed behind the crane to push the crane to the bridge. For the two end spans, track equipment (a tamper and ballast regulator) were added to the procession to re-surface the tracks at the approaches to match the new top of rail elevation of the new bridge spans. Once the gantry crane was positioned with legs firmly planted on the abutment and the top flange of span 2, the anchor bolts were cut out from under the old span 1. Chains were connected from the power dollies supported on the gantry truss to lifting lugs on the span and the lift began. After 10 minutes, the old span was suspended in the air. Within minutes, the old span was placed onto waiting buggies behind the crane and then moved to the staging area at the Wasa siding where it was off-loaded by the self-propelled trailers. Simultaneously, the old bearing seats were chipped away and forms for 4 new grout pads were installed. The new span was then lifted off the buggies in front of the crane and positioned. Slowly, the span was lowered into position and finally released once the grout hardened sufficiently to take the loads. New to old rail connections were made and tie plates under the rails on the span ahead were shimmed up to make up the difference in height between the new and old spans. After CP completed a track inspection, the tracks were reopened and the first span launch was completed within the 8 hour time limit. The remaining 7 spans were launched in a similar manner, all within the 8 hour time limit.

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Figure 4 - New TPG Temporarily Seated Next To The 1913 HDPG Until The Next Track Block

Figure 5 - Bridge Girder Removed From Span 8

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Figure 6 - Existing Span Removal: South Elevation View STABILIZATION OF BOTH ABUTMENTS WITH SOIL ANCHOR TIE BACK SYSTEMS  Monitoring of the two abutments of Br. 14.58 Windermere over the course of ten years indicated slow but gradual rotation of the abutments about the toe, away from driving earth forces. The exact cause of the movement was difficult to establish. Likely causes were: inadequate pile capacity of the initial design, high lateral earth loads due to a high water table in recent years and increases in live load surcharge. Also, it is worth mentioning, the river occupies the valley between the Purcell Mountains and Kootenay Ranges in a wide alluvial plane varying between 1 and 5 km wide. Soil underlying the abutments at the bridge crossing was found to be silty sands. It is suspected that the high permeability soils were subject to some heaving and washing behind the abutment with fluctuating river levels and water tables. It is common knowledge in the Wasa area that the ground water table would rise and fall with the level of the Kootenay River and Wasa Lake. The abutments at Br. 14.58 Windermere had sustained lateral movement – driven by lateral earth and surcharge pressures. The consequence of this movement was an encroachment of the abutment into the gaps separating the bridge girders and the ballast walls. In some cases, the ballast wall had been cut away to prevent contact with the steel girders. Any further aggravation of the situation could result in built up stresses and eventual deformation of the flanges and webs of the main girders at the ends of the bridge. Tie back anchor systems were designed to prevent any further movement of the abutments. The tie backs would anchor the abutment to subsoils behind the active failure zone of the retained earth. This would provide additional resistance against lateral earth and surcharge forces and compensate for reduced bearing capacity of insufficient piles founding the abutment. To install the tie back anchors the backwall was drilled through and boreholes were continued back to a maximum length of 25 meters behind the wall. Steel casings were used to prevent collapse of the drill holes. The installation of the tie back anchors on the South abutment went according to plan and design. White sand was consistently encountered behind the wall and 9 soil anchors were processed in a matter of days.

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Figure 7 - Processing tie back anchors

The installation of the tie back system proved to be much more difficult on the North abutment. Cuttings from the boreholes were wrought with pebble stones. The geotechnical field investigation had warned of boulders and cobbles but seams of pebbles were not expected behind the wall. These pebbles caused binding between casing and drill steel; on several occasions, high strength steel casing snapped. Close to ten 8 foot long steel casings were lost in the drill holes rendering the boreholes unusable. The designers then had to recalculate the drill pattern on the backwall and resubmitted the design. The drilling contractor continued working during the redesign period. A number of methods were attempted over the course of the next months to resolve the problem. Substantial quantities of lean concrete were pumped into boreholes only to realize that the volume of lean concrete that set in the holes was negligible. On one occasion, sinkholes developed beneath the tracks after intensive re-drilling of a borehole. Grout socks were then employed to limit grout losses in high void ratio soils (pebble stone pockets). Grout mobility limiting modifiers were introduced into the grout mix to coagulate the grout once injected into the bond zone. Pre-injection of the bond zone of problematic anchors from the embankment slopes above was also used to fortify the pebble seams into a unified mass. This finally yielded some useful results for the 2 lower rows of anchors. Finally, the top row of anchors was attempted – these proved to be the most trying. Heaving sands / underground water pressure filled the void created by drill holes and consistently pushed pebbles inside the end of the drill head and the casing. This made it impossible to remove the equipment without compromising the hole. The answer was a water pressure equalization strategy. This was done by means of high pressure water injection down the hole. This countered the reverse water flow that was naturally occurring. The equalization of the water pressure prevented the previously seen backflow and allowed for retraction of the casing once the tie back anchor was grouted in place without binding. After months of trial and error, and without interruption to railway operations, the final anchors were set in place, grouted and eventually locked off.

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Figure 8 - Tie back anchor design

JACKETING OF PIERS AND ABUTMENTS  To complete the full rehabilitation of the railway bridge, all substructures and superstructures needed to be renewed. The renewal of the foundations for a 100 year service life required the jacketing of all piers and abutments. Therefore all piers were scabbled down to sound concrete. Due to their unusual shape, pier noses consistently displayed the most spalling and scaling. Steel anchors were connected to the existing pier and abutment faces with polymeric quick setting grout. Reinforcing steel cages were then constructed around the entire structure, connected via the anchor bars. Finally, formwork was built up and fresh concrete was poured through the bridge deck from a Hi Rail concrete truck down into the formwork. After the formwork was stripped, the centenary piers and abutments looked just like new. CONCLUSION  The bridge project was completed in June 2014. Once the new bridge spans were in place, new CWR was installed and the track profile over the bridge and at the approaches was completely restored. The environmental impact of the bridge rehabilitation work on the Kootenay River was minimal due to the successful implementation of the overhead gantry crane. Impact on train operations was also minimal during the 12 months of construction. Slow orders have been removed from the tracks and trains have resumed maximum operating speeds on the new Br. 14.58 Windermere in Southeastern British Columbia.