21 Structural Conceptual Design Report

7/28/2019 21 Structural Conceptual Design Report

1/12

CWMM CONSULTING ENGINEERS LTD.

Ministry of Transportation and InfrastructureHighway No. 2

Tupper 4 lane UpgradeProject No. 36845 and 36846

Structures Conceptual Design Report

Prepared for:

R.F. Binnie and Associates Ltd.103-7382 Winston St.

Burnaby, B.C.V5A 2G9

Prepared by:

CWMM Consulting Engineers Ltd.200 - 1854 Kirschner Road

Kelowna, B.C.V1Y 4N6

Tel: 250-868-2308Fax: 250-868-2374

Contact: Donald D. Bergman, P.Eng.

Email: [email protected]

Job No. K3952 July 6, 2012


2/12


Ministry of TransportationHighway No. 2

Tupper 4 Lane Upgrade

Table of Contents

1.0 GENERAL ............................................................................................................ 11.1 Introduction ................................................................................................ 11.2 Design Criteria ........................................................................................... 1

1.2.1 General Design Criteria ................................................................... 11.2.2 Site Specific Criteria ........................................................................ 2

2.0 CONCEPTUAL DESIGN CONSIDERATIONS ..................................................... 22.1 General ...................................................................................................... 22.2 Factors Influencing Structure Type ............................................................ 3

2.2.1 Environmental Impact ...................................................................... 32.2.2 Hydrotechnical Issues ...................................................................... 42.2.3 Geotechnical Issues ........................................................................ 42.2.4 Constructability and Schedule ......................................................... 42.2.5 Maintenance .................................................................................... 5

3.0 RECOMMENDED CONCEPTS ............................................................................ 53.1 General ...................................................................................................... 53.2 Structure Details ........................................................................................ 6

3.2.1 Four Mile Creek at Station 111+52 .................................................. 63.2.2 Tupper Culvert Channel at Station 139+40 ..................................... 73.2.3 Tupper Creek Bridge Widening at Station 140+43 .......................... 7

Appendix A - Conceptual Design Option Drawings and Cost Estimates


3/12

Ministry of Transportation and InfrastructureHighway No. 2, Tupper 4 Lane Upgrade

Structures Conceptual Design Report Page 1


1.0 GENERAL

1.1 Introduction

The BC Ministry of Transportation and Infrastructure Project No. 36845 and 36846 -identified as Highway No. 2, Tupper 4 Lane Upgrade, will improve safety and traffic flowalong this stretch of highway. The proposed length of the upgrade is approximately 5.2kilometres, starting at km 1.5 from the Alberta border. There are three separatestructures that will be affected within the project extents Tupper Creek Bridge No.7144 at km 3.0, Little Tupper Culvert No. 6465, and Four Mile Creek Culvert No. 6466at km 5.9. There are a number of other smaller diameter culverts within the projectlimits that are less that 3.0m diameter, and therefore are not considered as structures.These include a 2.6m diameter culvert located directly adjacent to the Little TupperCulvert No. 6465.

The firm of CWMM Consulting Engineers Ltd. as a member of R.F. Binnies highwaydesign team, is responsible for carrying out Conceptual and Detailed Design on theabove noted structures. This report summarizes the conceptual phase and presentsthe preferred arrangement for the three noted sites, considering environmental andhydrotechnical requirements, costs and constructability, and geotechnical issues.

The overall project conceptual design presents three alignment options; Option 1 widening on both sides, Option 2 widening on west side, and Option 3 widening oneast side. For highway design and environmental reasons, it is understood thatwidening on both sides is preferred, hence this Structures Conceptual Design Report is

generally focused on the Option 1 alignment.

1.2 Design Criteria

1.2.1 General Design Criteria

Design shall be to the current Canadian Highway Bridge Design Code CAN/CSA S6-06,including CAN/CSA S6S1-10, and the Ministrys Supplement to CSA S6-06. Designshall be by a Professional Engineer registered in BC.

Design of the structures will be based on the current Canadian Highway Bridge Design

Code CAN/CSA S6-06, including CAN/CSA S6S1-10, and the Ministrys Supplement toCSA S6-06, with reference as applicable to the climatic information in the 2005 NationalBuilding Code of Canada. Where applicable, design for the new works will alsoincorporate the requirements of the various BC MoT documents, including the BridgeStandards and Procedures Manual, the Standard Specifications for HighwayConstruction, the Major Works Construction Agreement, the Proprietary StructureDesign Process, and the B.C. Supplement to TAC Geometric Design Guide, as well asthe Geometric Design Guide for Canadian Roads.


4/12




The design service life of the structures will be 75 years, with a corrosion designrequirement of 100 years for new structures. The design live load will be based on theBCL-625 truck loading or the comparable BCL-625 lane loading.

1.2.2 Site Specific Criteria

The project is located in Seismic Performance Zone 1 where detailed seismic analysisis not required, including the foundations and abutments. For bridge structures themain seismic requirements will be provisions of adequate seat lengths for thesuperstructure and provisions of adequate connections between the superstructure andthe substructure to resist seismic forces.

The Bridge Standards and Procedures Manual indicates the maximum transport weightlimit for bridge stringers to be the standard 64 tonnes, resulting in permissible girder

piece weights of approximately 43 tonnes. Discussions with Rapid-Span StructuresLtd. indicate that larger stringers can be shipped, up to approximately 56 tonnes, withthe appropriate overload permits.

A 50mm thick future wearing surface in concrete or asphalt has been allowed for in theconceptual design of all structure options.

The proposed highway cross section width of 22 metres clear between barriers is to bemaintained over the structures. Bridge barriers are the standard New Jersey type cast-in-place bridge parapet, with a galvanized parapet railing meeting the heightrequirements for a bicycle railing, per MoT standards. Barrier railings/parapets are

designed to satisfy the required PL-2 Performance level. For buried CSP structures,conventional CRB highway barriers will be continuous over the structure.

DWB Consulting Services Ltd. are be providing hydrotechnical and environmentaldesign for the project. Preliminary environmental recommendations have been putforth by way of email correspondence, and a Preliminary Hydrotechnical Design Brief,dated April 22, 2012, was received on April 25, then amended and re-issued on April26, 2012. The Preliminary Hydrotechnical Design Brief was further amended and re-issued on June 15, 2012.

AMEC - Environment & Infrastructure will be carrying out the geotechnical

investigations at the sites, and will carry out geotechnical design concurrently with thebridge and detailed highway design. To date some preliminary geotechnicalinformation and basic design parameters have been provided by way of email andtelephone correspondence.


5/12




2.0 CONCEPTUAL DESIGN CONSIDERATIONS

2.1 General

The existing bolted multi-plate culverts at Four Mile Creek and the Tupper culvertchannel are generally considered to be in good to fair condition with some localizedareas of deterioration as noted in our SPCSP Structures Condition Report, howevergiven their age of approximately 50 years, there can be no assurance or expectationthat they would be able to continue functioning throughout the full 75 year design life ofthis project. In addition, both of these structures are undesirable from an environmentaland hydraulics perspective, therefore replacement appears to be necessary. Theexisting bridge structure at Tupper Creek is only a few years old and is in very goodcondition, so widening it to accommodate the proposed four lane template is theobvious and logical solution.

The existing conditions at the Four Mile and Tupper culvert channel sites are quitesimilar, and there are a number of clear span bridge structure types that have beenconsidered, as well as an open bottom arch type structure. For bridge options theseshort to medium length single span structures are best suited to simple beam typesuperstructure components, such as prestressed concrete box stringers, prestressedconcrete I-stringers, and steel plate stringers. Brief consideration was given to morecomplex superstructure systems, such as cast-in-place concrete girders, trapezoidalconcrete box girders, trapezoidal steel box girders, and steel tied arch construction.These were eliminated as viable options as the structure size and site conditions do notwarrant the higher costs and constructability issues associated with these systems.

At the Tupper Creek Bridge site the use of prestressed concrete box stringers to widenthe existing bridge is the most logical and economical solution, by adding onto theexisting structure with the same components as the original construction.

2.2 Factors Influencing Structure Type

2.2.1 Environmental Impact

While early discussions considered leaving the existing culverts in place, with thenecessary modifications for the widened roadway, environmental recommendations

highly favour the replacement of the culverts with either clear span bridge structures oropen bottom arch structures at both the Four Mile site, and the Tupper culvert channelsite. There are a number of reasons for this recommendation including, the provision offish passage and improved habitat, and less restrictive environmental permittingrequirements. The area is noted as being heavily impacted by beaver activity, and therecommendations indicate that clear span bridge structures will provide the best beaverdam deterrent. It is recommended that wildlife crossings be introduced into the projectdesign where feasible, and beneath clear span bridge structures a flat bench can beincorporated into the embankment slope, adjacent to the stream for this purpose.


6/12




From an environmental impact perspective, the replacement of the existing culverts withclear span bridges appears to be the best solution at both sites, with open bottom arch

structures being less desirable, but a considerable improvement over the existingconditions. It appears that the open bottom arch structures would provide the desiredimprovements in the fish habitat, but would not address the wildlife crossing issue, norbe as effective at deterring problematic beaver dam building activity.

The proposed widening of the existing Tupper Creek Bridge will have minimal impact onthe environment, as the existing creek channel does not require modification.

2.2.2 Hydrotechnical Issues

The required clearance above the Q200 design elevation has not been finalized at this

conceptual stage but is thought to be a minimum of 1.5 metres, although there is someindication that 2.0 metre clearance may be required to meet navigable watersrequirements. Due to the high levels of beaver activity in the area, it appears to bedesirable to provide the maximum clearance that can be reasonably achieved, in orderto prevent the accumulation of debris.

The Preliminary Hydrotechnical Design Brief (June 15, 2012) indicates that the existingculvert crossings at Four Mile Creek and the Tupper culvert channel do not meet thecapacity of a Q200 design storm, and therefore must be replaced with larger capacitysystems. The Design Brief discussion focuses on culvert replacement with either clearspan bridge structures or open bottom arch structures, with preference towards bridge

structures.

The two Tupper Creek crossings act as one system in terms of flood levels, so asignificant increase in the capacity at the Tupper culvert channel is necessary in orderto reduce the current Q200 design elevation to an acceptable level. For clearancereasons the installation of a bridge structure is greatly preferred, however, an openbottom arch will reduce the Q200 design elevation enough to allow approximately 0.76mclearance at the widened existing bridge, which may be considered adequate but doesnot meet Ministry standards. At the Four Mile Creek site it is our understanding that theQ200 clearance requirements are satisfied with either a bridge or open bottom arch, butthat a bridge is preferable due to presence of beavers.

The excavation for the new creek channels at the existing culvert sites is assumed to beperpendicular to the highway for the bridge structure concepts. If the detailedhydrotechnical or environmental design requires a channel to be aligned on a skewrelative to the highway, then the new bridge structure can be set on the same skewangle. For the open bottom arch options we are showing the new structures alignedwith the existing culverts.

At all three sites the channel banks will be armoured with the appropriate class of riprap


7/12




keyed into the bank at the toe, similar to the conditions at the existing bridge.

2.2.3 Geotechnical Issues

Although the geotechnical investigation has not been completed at this point in time,the use of driven steel pipe piles is considered to be necessary for support of thesubstructure elements at all three sites, based on the known conditions at the existingTupper Creek Bridge. The preliminary information indicates that permanent cut / fillslopes in the vicinity of bridge structures must not be steeper than 2H:1V. If thedetailed geotechnical design allows for steeper slopes, there is a possibility that theconceptual bridge lengths could be reduced slightly, from those presented. Thegeotechnical engineer has indicated that temporary cut slopes of 1.5H:1V may beallowed during construction.

2.2.4 Constructability and Schedule

As noted previously the overall project preferred option maintains the existing centerlineof highway, and is widened on both sides. The construction of the crossing structureswill likely be staged, and although the details of traffic flow requirements are not knownat this time, it is obviously desirable to choose structure types that can be constructedrelatively quickly in order to reduce the impact on traffic. Further, construction methodsand staging that will allow for the passage of vehicles without requiring major detourconstruction will be desirable from a cost perspective.

At both of the culvert replacement sites the excavation required to construct the piled

foundations for an open bottom arch structure will be very large, due to the much lowerelevation of the arch foundations as compared to bridge foundations. As a result, thebottomless arch structures will therefore likely require the construction of a detour roadand bridge offline, on the west side of the highway. For the clear span bridge structuresat both sites, it appears that two way traffic could likely be accommodated by building atemporary lane to the west of the existing shoulder, then constructing the east half ofthe bridge. Approximately 40% of the channel excavation and culvert removal could beaccomplished concurrently with the east half construction. Once completed traffic couldbe moved to the bridge, and the remainder of the excavation, culvert removal, andbridge construction could be completed.

Bridge substructure components and construction methods are essentially the sameregardless of the superstructure type selected, and there will be little difference in thetime to construct. Depending on the type of superstructure, the time to construct variesconsiderably with the formed cast-in-place deck on individual stringer types requiringthe longest time. These include both steel plate stringers and prestressed concrete I-stringers. Prestressed concrete box stringers will have a clear advantage over the otheroptions in terms of the length of construction time, as once the stringers are in place thedeck is nearly completed.


8/12




At the existing bridge site the traffic will remain on the bridge, shifted to one side as oneopposite side is widened, then moved over and the remainder of the widening will becompleted. There will likely need to be a relatively short temporary retaining wall

constructed to support the roadway adjacent to the first phase abutment excavations,possibly utilizing battered lock-blocks.

2.2.5 Maintenance

In general, bridge structures without deck joints incur less maintenance than those thatutilize deck joints, and for these single span structures deck joints could be eliminatedregardless of the superstructure type chosen. Bridge stringers with exposed bottomflanges tend to collect debris and attract nesting birds which can be a maintenanceitem, and in this regard the prestressed concrete box stringers have an advantage.Open bottom arch structures generally have very low maintenance requirements.

3.0 CONCEPTUAL DESIGN OPTIONS

3.1 General

Of the bridge superstructure options that were considered, the prestressed concretebox stringers are most favourable due to the streamlined construction. There shouldalso be some economy of scale by selecting similar structure types for all threelocations, and the concrete box stringers are clearly the obvious choice for widening theexisting bridge. Proprietary structural plate corrugated steel arch structures are alsoconsidered as options for the Four Mile and Tupper culvert channel sites.

In determining costs, representative data from other past projects have beenincorporated as applicable, including the existing Tupper Creek Bridge which wasconstructed in 2008. The prestressed concrete box stringers for the existing bridgewidening and the new proposed bridges can be sourced from several suppliers, theclosest being located in Edmonton AB. Preliminary cost data for the proprietary archstructures was obtained from Atlantic Industries Ltd., and these products can besourced from other suppliers.

The conceptual drawings and conceptual cost estimates are appended to this report.

It should be noted that these conceptual cost estimates for the arch structures donot include any materials above one metre beneath finished highway grade. For

direct cost comparison between arch options and bridge options the cost of the

roadway aggregates, asphalt, and concrete roadside barriers over a given bridge

length will need to be added to the corresponding arch cost estimate.


9/12




3.2 Four Mile Creek at Station 111+52

3.2.1 Bridge Structure Details

Currently Four Mile Creek traverses Highway No. 2 through a non-embedded 3.2mdiameter multi-plate culvert, with the inlet invert located at approximately 7 metresbelow the highway elevation. The culvert lies at approximately a 3 degree skew relativeto the highway centerline.

The proposed new bridge will be a single span structure positioned approximatelycentred over the centerline of the culvert, and have an overall length of 30 metres. Thebridge abutments consist of a single row of cantilever steel pipe piles topped with aconcrete cap, which will incorporate 90 degree return wing walls to retain the roadwayfills. The superstructure elements are 1100mm deep prestressed concrete box

stringers, with a composite 150mm thick (nominal) reinforced concrete deck slab. Theelastomeric bearings will be fixed at both ends, and will incorporate galvanized steeldowels for fixity and to provide lateral restraint. We have made allowance under deadloads for a future 50mm thick asphalt overlay and membrane, however these are notassumed to be installed at this time.

The estimated construction cost for the structure is $2,610,000, and includes thechannel excavation and riprap embankment protection, and the traffic managementcosts for the bridge construction.

Refer to drawing C-S1 for the general arrangement of the proposed bridge structure.

3.2.2 Arch Structure Details

The proposed new structure is a high profile arch with a bottom span dimension of6.045m, a total rise of 4.445m, and an end area of 26.41 square metres. The overallhorizontal length of the arch is 56m The arch foundations consist of a single row ofdriven steel pipe piles topped with a concrete pile cap.

The estimated construction cost for the structure is $2,349,000 and includes all itemsup to one metre beneath finished grade, including channel excavation, riprapembankment/foundation protection, and the traffic management costs.

Refer to drawing C-S1A for the general arrangement of the proposed arch structure.


10/12




3.3 Tupper Culvert Channel at Station 139+40

3.3.1 Bridge Structure Details

Currently this channel of Tupper Creek traverses Highway No. 2 through a non-embedded 3.2m diameter multi-plate culvert, with the inlet invert located atapproximately 6.5 metres below the existing highway elevation. A 2.6m diameterculvert is located alongside with the inlet invert approximately 1.7 metres higher thanthe larger culvert. The culverts lies at approximately a 5 degree skew relative to thehighway centerline.

The proposed new bridge will be a single span structure positioned approximatelycentred over the centerline of the 3.2m diameter culvert, and have an overall length of33 metres. The bridge abutments consist of a single row of cantilever steel pipe piles

topped with a concrete cap, which will incorporate 90 degree return wing walls to retainthe roadway fills. The superstructure elements are 1300mm deep prestressed concretebox stringers, with a composite 150mm thick (nominal) reinforced concrete deck slab.The elastomeric bearings will be fixed at both ends, and will incorporate galvanizedsteel dowels for fixity and to provide lateral restraint. We have made allowance underdead loads for a future 50mm thick asphalt overlay and membrane, however these arenot assumed to be installed at this time.

The estimated construction cost for the structure is $2,912,000, and includes thechannel excavation and embankment protection, and the traffic management costs forthe bridge construction.

Refer to drawing C-S2 for the general arrangement of the proposed bridge structure.

3.3.2 Arch Structure Details

The proposed new structure is a low profile arch with a bottom span dimension of11.680m, a total rise of 4.800m, and an end area of 45.51 square metres. The overallhorizontal length of the arch is 52.2m. The draft Preliminary Hydrotechnical DesignBrief recommended a structure with significantly less end area, but subsequentdiscussions with the hydraulics engineer led to the structure being revised to the currentcross sectional dimensions. The arch foundations consist of a single row of driven steel

pipe piles topped with a concrete pile cap.

The estimated construction cost for the structure is $2,579,000 and includes all itemsup to one metre beneath finished grade, including channel excavation, riprapembankment/foundation protection, and the traffic management costs.

Refer to drawing C-S2A for the general arrangement of the proposed arch structure.


11/12




3.4 Tupper Creek Bridge Widening at Station 140+43

The existing bridge is a single span structure with a 22.6 metre overall length,

comprised of 800mm deep prestressed concrete box stringers, a 100mm thick un-reinforced concrete slab on top of the boxes, overlain with 75mm of asphalt. Theexisting abutments consist of a cast-in-place concrete footing and abutment wall,bearing on staggered 406mm diameter steel pipe piles.

The new abutments will be constructed with driven steel pipe piles supporting theconcrete footings, abutment walls, and wing walls. 800mm deep prestressed concretebox stringers will bear on elastomeric bearing pads, and a concrete slab with asphalttopping will cover the box stringers, all similar to the existing structure.

There will be some variation on the extent of demolition required at the interface

between the existing and new components, as well as the outer edge details,depending on the final alignment chosen. With the preferred centerline widening theexisting bridge parapets and wing walls will be removed on both sides, whereas with thewest side widening they only need to be removed on one side.

The estimated construction cost for the widening of this structure is $1,348,500, andincludes the embankment protection, the traffic management costs for the bridgeconstruction, and the demolition of the existing bridge parapets and wing walls on bothsides.

Refer to drawing C-S3 for the general arrangement of the proposed structure.

4.0 RECOMMENDATIONS

The initial proposal to retain the existing multi-plate culverts at Four Mile Creek and theTupper culvert channel does not appear to be acceptable for reasons of longevity aswell as hydraulics and environmental issues, so these structures must be replaced.

The installation of clear span bridge structures at both sites is preferred over the openbottom arch option by both environmental and hydrological recommendations, and thebridge options appear to be better suited to staged construction and accommodation oftraffic, due to the prohibitively large excavations required for open bottom arch

construction. It is possible that the structures may be able to be made shorter withconsideration of steepened fill slopes (ie, steeper than 2:1) if deemed acceptable froma geotechnical perspective, thus reducing costs.

For the widened bridge structure at Tupper Creek, the box stringer superstructuremimicking the existing bridge is the obvious and preferred solution. As noted, the Q200clearance is found to be inadequate based on the bottomless arch structure concept atthe Tupper culvert channel, however a bridge structure at this location appears toalleviate this issue.


12/12




Upon considering all of the factors that influence the recommended structure type forthese crossings, we believe that a clear span bridge utilizing prestressed concrete box

stringers will provide a cost effective solution that can be constructed relatively quickly,and will best satisfy the environmental concerns of the local stakeholders.

Report Submitted by:

CWMM Consulting Engineers Ltd.

Per: Don D. Bergman, M.Eng., P.Eng., Principal

Documents

21 Structural Conceptual Design Report