Chapter Design ConsiderationsTrestle ComponentsTrestle Civil DesignTrestle600.06600.07600.08600.09Trestle Structural DesignBulkhead Structural DesignVTS Bridge Seat Structural DesignTrestle Utilities600.01 GeneralThis chapter provides guidance on the design of trestles, bridge seats, and bulkheads.GeneralThe trestle is a pile-supported structure, as shown in Exhibit 600-1, which serves as aroadwayfrom theonbulkheadvehicletransfer(VTS). ForThesomeThischapterconnectionprovides guidancethe designtoofthetrestles,bridgeseats,spanand bulkheads.trestleisterminals,a pile-supportedstructure,as shownwhichservesonas thea roadwaythe vehicleholdingarea inis Exhibitfully romthe bulkheadto the vehicletransfer(VTS).For maysomealsoterminals,the rtareasbe locatedon hibit 600-2 and Exhibit 600-3 show an example layout of a trestle in plan andandcrosssupportareasmay also beInlocatedon the trestle.Exhibitholding600-2 andExhibit600-3 showansection,respectively.this example,the vehicleareais exclusivelylocatedonexample layout of a trestle in plan and cross section, respectively. In this example, the vehiclethe trestle.600.01holding area is exclusively located on the trestle.The trestle may also provide a pedestrian access path from the bulkhead to the terminalThe trestle may also provide a pedestrian access path from the bulkhead to the terminal building.building. Further, the trestle may serve as the support structure for the overheadFurther, the trestle may serve as the support structure for the overhead loading (OHL), VTS,loading (OHL), VTS, terminal buildings, and various utilities, related equipment andterminal buildings, and various utilities, related equipment and structures. Use the trestle to runstructures.the trestleto run transferutilitiesspans.from Forthe landto the vehiclespans. Forutilitiesfrom Usethe landto the vehiclerecommendationsontransferrouting posts and trench drains, refer tolocatinglight posts anddrains,referlocatingto Sectionlight600.09.Section 600.09.ClintonClinton TrestleTrestle SubstructureSubstructureExhibitExhibit 600-1600-1For additional information, see the following WSF Terminal Design Manual M 3082.05320Environmental ConsiderationsApril 2016330MarinePage 600-1

TrestleChapter 600For additional information, see the following 70610620Page 600-2SubjectAccessibilitySecurityEnvironmental ConsiderationsMarineCivilElectricalMaintenance Buildings, Enclosures and Support AreasAccess, Approaches, and ExitsToll PlazaVehicle Holding and Support AreasSite UtilitiesSignage and WayfindingVehicle Transfer SpanPassenger Overhead LoadingWSF Terminal Design Manual M 3082.05April 2016

Chapter 600TrestleChapter 600TrestleExample Trestle PlanExhibit 600-2Example Trestle PlanExhibit 600-2Terminal Design Manual M 3082WSF TerminalDesign Manual M 3082.05August2015April 2016Page 600-3Page 600-3

TrestleChapter 600TrestleChapter 2ReferencesUnlessnoted,otherwisenoted,any code,standard,or otherpublicationhereinUnless otherwiseany code,standard,or otherpublicationreferencedhereinreferencedrefers to thereferstothelatesteditionofsaiddocument.latest edition of said document.(1)(1) 28 CFR Part 35 Nondiscrimination on the Basis of Disability in State and Local28 Code of Federal Regulations (CFR) Part 35, Nondiscrimination on the Basis of Disability inGovernmentServicesState and LocalGovernmentServices49 CFR Part 39 Transportation for Individuals with Disabilities – Passenger Vessels49 CFR Part 39 Transportation for Individuals with Disabilities – Passenger VesselsWAC 296-24 General safety and health standardsWashington Administrative Code (WAC) 296-24, General safety and health standardsWAC 296-56 Safety Standards - Longshore, stevedore and waterfront relatedWAC 296-56,Safety Standards - Longshore, stevedore and waterfront related operationsoperationsWAC Ladders,and fixedDesignCodesSpecifications(2)(2) DesignCodesandandSpecificationsAASHTO AASHTOLRFD BridgeDesignSpecifications(AASHTO LRFDSpecification),LRFDBridgeDesign sociationAmericanof State Highwayand TransportationOfficials,Washington DCOfficials, Washington DCAssociationof State Highwayand TransportationAASHTO AASHTOGuide Specificationsfor LRFD SeismicBridgeSeismicDesign Bridge(AASHTOGuideGuide Specificationsfor LRFDDesign(AASHTO ion), American Association of State Highway and TransportationOfficials,DCWashington DCBridge DesignManualLRFD,M 23-50,WSDOTBridgeDesignManualLRFD,M 23-50ASCESeismicDesignPiers andWharves, ASCE/COPRI61-14, 2014,ASCE SeismicDesignof Piersand ofWharves,ASCE/COPRI61-14, 2014, AmericanSocietyAmericanofCivil Engineers,Reston,VA.Society of Civil Engineers, Reston, VA.GeneralSpecial WSDOTProvisionsGeneral SpecialProvisions,HighwayRunoffManualM 31-16Highway RunoffManual(HRM),M 31-16,WSDOTReference Drawings, WSFPage 600-4Page 600-4Regional General Special Provisions, WSFTerminal Design Manual M 3082August 2015Standard Specifications for Road, Bridge, and Municipal Construction M 41-10WSF Terminal Design Manual M 3082.05April 2016

Chapter 600(3)TrestleSupporting InformationLife Cycle Cost Model (LCCM), WSF600.03 Design Considerations(1)AccessibilityWherever pedestrian facilities are intended to be a part of a transportation facility,28 CFR Part 35 requires that those pedestrian facilities meet ADA guidelines. Federalregulations require that all new construction, reconstruction, or alteration of existingtransportation facilities be designed and constructed to be accessible and useable bythose with disabilities and that existing facilities be retrofitted to be accessible.Additionally, 49 CFR Part 39 prohibits owners and operators of passenger vessels fromdiscriminating against passengers on the basis of disability, requires vessels and relatedfacilities to be accessible, and requires owners and operators of vessels to take steps toaccommodate passengers with disabilities.Design pedestrian facilities to accommodate all types of pedestrians, includingchildren, adults, the elderly, and persons with mobility, sensory, or cognitivedisabilities. Refer to Chapter 300 for accessibility requirements.(2)SecurityChapter 310 includes a general discussion of the United States Coast Guard(USCG) three-tiered system of Maritime Security (MARSEC) levels, vessel securityrequirements, and additional information pertaining to terminal design. Below are linksto relevant sections by topic. Coordinate with the WSF Company Security Officer(CSO) regarding design issues pertaining to security. In addition, coordinate with theUSCG and Maritime Security for all terminals, the United States Customs and BorderProtection (USCBP) for international terminals, and the Transportation SecurityAdministration (TSA) for Transportation Worker Identification Certification (TWIC)and Sensitive Security Information (SSI). MARSEC Levels: 310.04 Vessel Security: 310.05 Waterside Structures: 310.09 Access Control/Restricted Areas/TWIC: 310.10(3)Environmental ConsiderationsRefer to Chapter 320 for general environmental requirements and design guidance.Refer to the project NEPA/SEPA documentation for project-specific environmentalimpacts and mitigation.WSF Terminal Design ManualApril 2016M 3082.05Page 600-5

Trestle(4)Chapter 600CivilRefer to Chapter 340 for general civil design criteria pertaining to the trestle. Beloware links to relevant sections by topic. Design Vehicles: 340.07(6) Vehicle Turning Analyses: 340.07(7)(5)MarineRefer to Chapter 330 for marine criteria pertaining to the trestle. Below are links torelevant sections by topic. Operations and Maintenance: 330.04(4) Proprietary Items: 330.04(6) Long Lead Time Items: 330.04(7) Corrosion Mitigation: 330.04(9) Scour and Mudline Elevations: 330.04(10) Geotechnical Requirements: 330.04(11) Materials Specification: 330.04(12) Miscellaneous Considerations: 330.04(13) Tidal Information: 330.06 Wave, Flood, and Coastal Storm Loading: 330.09(1) Paving: 340.08(6)ElectricalRefer to Chapter 360 for general electrical design criteria pertaining to trestles. Beloware links to relevant sections by topic. Wiring and Protection: 360.04 Wiring Methods and Materials: 360.05 Equipment: 360.06(7)Design LifeDesign life is based on the current Life Cycle Cost Model (LCCM) as required by theWashington State Office of Financial Management (OFM). Refer to Table 1 for thedesign life of new structures (as of 2007) and Table 2 for design life of structures priorto 2007, in the 2010 Life Cycle Cost Model Update (2010 LCCM) for information onwhen existing marine structures and their systems are due for replacement. Confirmdesign lives given below are consistent with the current LCCM. Replacement life maybe reduced due to functional obsolescence. Trestle Substructure: 75 years Trestle Superstructure: 75 years Bulkhead: 75 yearsPage 600-6WSF Terminal Design Manual M 3082.05April 2016

Chapter 600(8)TrestleElevationThe trestle elevations are controlled by the bulkhead elevation at the onshore endof the trestle, the bridge seat elevation at the offshore end of the trestle and anyslope required for stormwater conveyance/treatment. Consider the following whenselecting the bridge seat elevation: (1) resulting vehicle transfer span slopes; (2) trestleconstructability; (3) trestle inspection needs; (4) anticipated sea level rise; (5) existingroad profile/grade at shoreline/bulkhead; (6) storm surge/wave exposure.Provide an elevation which is a compromise between keeping the trestle sufficientlyhigh out of the seawater to keep it constructible (to avoid floating pile cap forms athigh tide) and to minimize the potential for damage to the trestle/trestle utilities (fromwaves, sea level rise, storm surge and floating debris), and keeping it low enough tominimize the steepness of the vehicle transfer span at extreme low tides. It is advisableto provide adequate room beneath the trestle for post-seismic event inspections. Referto Section 330.06(3) for information on anticipated sea level rise.(9)Operational ClassificationWSF trestles are operationally classified per the AASHTO LRFD Specification Section1.3.5 as typical, not critical or essential, unless noted otherwise. The performanceobjective for “typical” bridges is life safety. See Section 600.06(1)(c) Limit States foruse of this classification.(10) Seismic DesignPerform seismic design of the trestle using a displacement-based design method inaccordance with the AASHTO Guide Specification and supplemented as describedherein. Design trestle for a design level earthquake (DLE) corresponding to a 7-percentprobability of exceedance in 75 years (approximately a1000-year return period) with alife safety protection/collapse prevention performance objective. It is expected that thetrestle will continue to support gravity loads after the DLE but may suffer significantdamage and that significant disruption to service is possible.Structures shall also be checked for an operational level earthquake event (OLE).This is an event in which no damage or only minor structural damage will occur,but a temporary interruption in service may occur.This event corresponds to a 50-percent probability of exceedance in 75 years(approximately a 100-year return event). Expansion joint design and locations wherethe relative displacement of different structures could cause damage shall be checkedfor this level earthquake event. Soil parameters for developing seismic responsespectra will be provided by the WSDOT Geotechnical Branch.The designer shall identify in the general structural notes of the contract drawings theanticipated structural failure mode and locations for both the OLE and the DLE.For seismic design of pile foundations, plastic hinging is limited to above ground andnear-ground locations. In-ground plastic hinging is not permitted.For geotechnical requirements, refer to Chapter 330.WSF Terminal Design ManualApril 2016M 3082.05Page 600-7

TrestleChapter 600(11) Accelerated Bridge ConstructionAccelerated bridge construction methods such as precast concrete or steel bridgeseat and trestle pile caps in the design are options where the duration of slip closuresmust be kept to a minimum. Use of these methods minimizes interruptions duringconstruction and can be cost effective at terminals with high traffic volume.(12) Expected Material PropertiesAssess member capacities for earthquake loads using expected material properties inaccordance with the AASHTO Guide Specification. Supplement expected materialproperties only where necessary by ASCE/COPRI 61-14.(13) Signage and WayfindingRefer to Chapter 570 for requirements.600.04 Trestle Components(1)Superstructure(a)Concrete DeckDesign the trestle deck to consist of precast prestressed concrete deck panels. A varietyof deck panel types have been used successfully at WSF terminals. Design deck panelend connections for moment continuity over the pile caps to resist seismic forcesand negative moments from super-imposed dead and live loads. Design the deck as acapacity-protected element, such that no inelastic deformations will occur. Yielding ofthe pile-to-cap connection is allowed.Adjacent deck panels should be locked together by means of shear keys to allow forload sharing.The depth of concrete deck members may be limited to prevent damage from floatinglogs