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Project Preparation and Project Preparation and AdministrationAdministration
Bridge ModuleBridge Module
R1 Trails Project PreparationR1 Trails Project Preparation
Why are bridges part of this trainingWhy are bridges part of this training??
• Big cost.• Long
Process• Design is
complicated• Tough
Decisions
R1 Trails Project PreparationR1 Trails Project Preparation
But they are Fun!But they are Fun!
Trails do nothing more than connect the Bridges!
Proud crew!
R1 Trails Project PreparationR1 Trails Project Preparation
Training FocusTraining Focus
• Bridge Design Process Decisions to be
made. How to make those
decisions!
R1 Trails Project PreparationR1 Trails Project Preparation
Training FocusTraining Focus• Northern Region Standard Trail Bridge Plans
Intended uses Limitations, Inappropriate Uses Costs Maintenance
• Wilderness Bridges• Helicopter Usage• Preservative TreatmentsIf there is time – NP Wilderness Bridge Project
Presentation
R1 Trails Project PreparationR1 Trails Project Preparation
AuthoritiesAuthorities• All Decisions –
Line Office• Approval of
Bridge Design – Director of Engineering Unless using
Regional Standard Trail Bridge Designs – Forest Engineer.
• All Trail Bridges need to be designed!
Bridge in Bob Marshall Wilderness
R1 Trails Project PreparationR1 Trails Project Preparation
AuthoritiesAuthorities• Design Resources
Available. Forest Engineer Regional Bridge Group
John Kattell David Scovell
• Our job is to provide technical assistance to Forest personnel and complete and/or approve all bridge designs.
R1 Trails Project PreparationR1 Trails Project Preparation
Project Scope**
Location/Survey
Final Design
Construction
Preliminary Design
Bridge Design ProcessBridge Design Process•Function (To bridge or not? Replace or remove?)
•Who is User? ROS? TMO?
•Force Account/Contract?
•Where is best spot?
•Many decisions.
•Project Funding and Scope finalized.
•COR
•Plans, Specs, Estimates.
**Contact FE and /or RO during Project Scope
R1 Trails Project PreparationR1 Trails Project Preparation
Project Initiation and ScopeProject Initiation and Scope
• Function To Bridge or Not to
Bridge? Replace or remove? Preliminary Engineering
needed?• Factors?
TMO & ROS User Safety Resource Protection Others?
Funding FeasibilityAesthetics WildernessAlbino Trail Bridge Site - Gal
R1 Trails Project PreparationR1 Trails Project Preparation
Bridge Design ProcessBridge Design Process
• In general, more complicated than road bridges. Why? Defining the User Location
Access Wilderness
Size?
R1 Trails Project PreparationR1 Trails Project Preparation
Bridge Design ProcessBridge Design Process
• Dome Mtn. On Ktn. 24-foot span Wilderness 6-mile from TH but
4000 ft elevation gain.
Force Account Dangerous work.
R1 Trails Project PreparationR1 Trails Project Preparation
Bridge Design ProcessBridge Design Process
• Iron Springs on D-P 50-foot span Easy access Total cost -
~$35,000 Contract
Maah-Taah-Hey Trail
R1 Trails Project PreparationR1 Trails Project Preparation
Project Initiation and ScopeProject Initiation and Scope
Define the User (TMO & ROS) Pedestrians Stock ATVs Bicycles Administration
vehicles Outfitters / other
permittees User affects size, design
and cost. Bridge many times limits
the user!
R1 Trails Project PreparationR1 Trails Project Preparation
Project Initiation and ScopeProject Initiation and Scope• Force Account or Contract? (Effects design
decisions!) Design (in house or A/E)
Complexity of bridge project. Availability of Forest or RO Engineers Funding Typically, R1 designs are done in house.
Construction Safety Force Account capability, skill level, and availability. Complexity of bridge. Funding Pros and Cons
R1 Trails Project PreparationR1 Trails Project Preparation
Force Account or Contract?Force Account or Contract?
• Remote site required packing all materials.
• Simple construction
• NP has trained Crews.
• Force Account
Goat Creek on NP
R1 Trails Project PreparationR1 Trails Project Preparation
Force Account or Contract?Force Account or Contract?
• Bridge part of a larger trail construction project.
• Short distance from trailhead.
• Complicated construction
• Contract
Yellow Mule on Gallatin
R1 Trails Project PreparationR1 Trails Project Preparation
Force Account or Contract?Force Account or Contract?
• Site at trailhead.• Working over
large water penstock and tracks.
• Needed large equipment
Mystic on Custer
Contract
R1 Trails Project PreparationR1 Trails Project Preparation
Project Initiation and ScopeProject Initiation and Scope
• SummaryFunction (To bridge or not to bridge)Define Users.Force Account versus Contract Funding. Project a go or no go?May need some preliminary engineering
this early.
Who makes these decisions?
R1 Trails Project PreparationR1 Trails Project Preparation
Location / SurveyLocation / Survey• Location
Narrowest spot? Not necessarily
Stable stream reach. Where users want it! Good trail
approaches for user (function for hikers vs stock vs snomobiles vs ATV’s)
• Survey - Varies Simple small creek
Profile of trail and stream with few x-sections.
Sketches Complex
Full site survey of area.
Geotechnical (drilling) In general, experienced
bridge engineer may get by with less.
R1 Trails Project PreparationR1 Trails Project Preparation
Location / SurveyLocation / Survey
•Holter Cut on Btr.
•No survey done.
R1 Trails Project PreparationR1 Trails Project Preparation
Location / Location / SurveySurvey
•Little Salmon on Flathead in Bob Marshall.
•Full site survey completed.
•Needed for hydraulic analysis.
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design Determine
Span Height Width Bridge Type Foundations FA or Contract Cost
FactorsCrossing and heightFlood waters, Clearance UserSpan, location, aestheticsSite geologySee earlier slideAll of the above.
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
Two biggest problems in R1
Bridges too short.
Abutments scour and fail
Resource damage
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
Bridges are too low!
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Sill-Thru Configuration Little work in
water. Hydraulically
efficient. (less susceptible to scour).
More $ in superstructure, less in abutments.
No wingwalls needed.
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design• Vertical Wall
Configuration More work in
water. Hydraulically less
efficient. (more susceptible to scour).
Less $ in superstructure, more in abutments.
Need wingwalls
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Span Length Field Estimate (Rule of Thumb) typical spill-thru bridge.
Estimated Span Length (L) = BW + 3 x BH BW – Channel bottom width BH – Bridge height from channel bottom to trail tread.
Span Length (L)
BH
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design• Span Length
Field estimate must be verified on paper.Do not undersize.
Better to spend more on span than abutments.Evaluate existing bridge (did it function OK)
Iterative process with what? Bridge height
What controls bridge height?
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• What controls bridge height? Trail height Bridge structure
depth Rule of thumb
1/20 x span Clearance for debris
Minimum 2 feet above high water (100 yr flood) to bottom of bridge.
Little Salmon on Flathead
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Span Length – Vertical Wall abutment
Span Length = Bankfull +. Must be able to pass flood without damage to bridge or stream.
Footings must be ‘below stream bed as minimum unless on bedrock.
Span Length (L)
BH
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
Factors for Bridge Width - Users - Railing
Bridge w/o railing
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
Variable widths• Single log – 14”• Stock w/railing – 8’• Snowmobile –
16’+• Manual guidance
but can be anything.
Bridge with railing
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design• Bridge Types
Single Log Timber stringer Glu-lam stringer Truss Suspension Packable
• FactorsSpan Access
Aesthetics Materials
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Foundations Spread footings Gabions Geocell Walls
• Generally we use spill-thru configuration with timber sill on gabion or geocell.
• Factors Site geology Site materials Access Scour Potential
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• CostsVery difficult to estimate.No rules of thumb.Procedure
Take off and price materials (variable) Crew up labor.
$2500/day for crew of 4 with misc.tools/equipment Or use Davis Bacon rates
Estimate Equipment needed (cranes, backhoe, helicopter)
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design• Costs - continued
Materials Sawn Timber $1350/mfbf GL timber $2500/mfbf Bolts/hardware $3.00/lbs. Concrete $600 - $1000/cy Reinforcing Steel $1.25/lb Gabions $125/cy Geocell $15/cy Geocell fill $25-$75/cy
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design• Costs - continued
Equipment Excavator $130/hr Backhoe $80/hr Dump Truck $75/hr Crane (Light) $350/hr Crane (medium) $650/hr Helicopters See later slides
Packing $225/mule trip (180 lbs per mule)
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Typical work items to accomplish for labor.
Project Management Mobilization Excavation Build Abutments Install Superstructure Build Approach walls Build Approach fills
• Less Common Work Items Helicopter use. Packing Materials Supply Camp Install Falsework.
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• Nail Lam built 15 years ago.
• Replace with glu-lam stringer bridge.
• On sills.• Wilderness• Use Helicopter to fly
in stringers.• Estimate based on
Contract Construction
Flood Creek – Custer
R1 Trails Project PreparationR1 Trails Project Preparation
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary DesignWhose Responsibility / Authority for
preliminary decisions?
Forest!• However, Engineering must assist! • Why?• Call FE and or RO during Project Scope for
assistance with alternatives and options. Meet with Rec staff and Ranger to discuss
preliminary design options and alternatives.
R1 Trails Project PreparationR1 Trails Project Preparation
Preliminary DesignPreliminary Design
• At this pointRe-evaluate Project Scope!Re-evaluate Funding!
• Why?Many times each site has several
alternatives being evaluated.Must select Final Design Alternative.
R1 Trails Project PreparationR1 Trails Project Preparation
Final Design, PS&EFinal Design, PS&E
Typically done by Engineering• Plans (as a minimum)
Title Sheet (signatures)Bridge Layout (Plan and Elevation)
On site plan from survey.Abutment/foundation detailsSuperstructure detailsMiscellaneous details
R1 Trails Project PreparationR1 Trails Project Preparation
Final Design, PS&EFinal Design, PS&E
• SpecificationsFP-03, Standard Specifications for
Construction of Roads and Bridges on federal Highway Projects.
Special Project Specifications as needed.
R1 Trails Project PreparationR1 Trails Project Preparation
Final Design, PS&EFinal Design, PS&E
• EstimatesEstimated Construction Costs
Update of preliminary estimateEstimated Schedule for Construction
R1 Trails Project PreparationR1 Trails Project Preparation
Final Design, PS&EFinal Design, PS&E• Plans, Specs and Estimates
All 3 required.Any difference for Force Account vs
Contract? Shouldn’t be!
Authorities Regional Engineer must approve PS&E
package, UNLESS Using Standard Plans, then FE has authority
to approve PS&E package.
R1 Trails Project PreparationR1 Trails Project Preparation
ConstructionConstruction• All Trail Bridge Construction is to be
administered and inspected by Certified COR, Level IIIWith appropriate technical endorsements.Any difference for Force Account vs
Contract? NO!
RO will assist as needed or requested.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans
• Pre-designed and detailed drawings for: Typical Trail
Bridge Superstructures
Typical simple substructures (sills).
Iron Springs on Maay-Daay-Hey Trail
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Intended Uses
Simple, single spans Spans less than 60 feet Adapted for each site. FE can approve.
• Limitations At discretion of FE only. Not for complex bridges. Not for difficult
abutments. Still requires, survey,
hydraulic analysis, soils, etc.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansTypical Superstructures: Drawing #
Solid Sawn Timber Stringer R1920 Log Stringer R1921 Glu-lam timber stringer R1922 Glu-lam longitudinal slab R1923 Single log R1924 Nail-lam longitudinal slab R1925 Prefabricated steel truss R1926 Packable spliced stringer R1927
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansTypical abutment details Drawing #
Various types of sills used R1930-34
Will need to be customized for each site.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Sawn Timber Stringer
Spans 10 to 40 feet Any width Stringers 3x10 to 8x24 ROS - ??? Economical if you have
used stringers. But stringer quality large
than 4x10 gets iffy. Costs increase
significantly with larger stringers.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansSawn StringerSawn Stringer
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Log Stringer
Spans 10 to 45 feet. Any width. Diameter from 8” to
22” ROS – ??? Costs are higher
Than other types for similar spans.
More difficult to build and maintain.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansLog StringerLog Stringer
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Glu-laminated Stringer
Spans 25 to 60 feet. Any width. Stringers 3.125 x 15 to
8.75 x 39. Requires diaphragms. ROS - ???? Most ecomomical for
spans 40 feet or longer. Easy construction but
requires larger equipment. Low maintenance.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansGL StringerGL Stringer
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• GL Longitudinal Slab
Spans 10 to 35 feet. Best for widths < 8’. Come in panels, max
4’ width. ROS - ??? Very ecomomical Easy to build. Low maintenance Handrail more difficult
to attach.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansGL Longitudinal SlabGL Longitudinal Slab
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans
• Single Log Stringer User is hiker only. Spans 10 to 45 feet. Diameters 16” to 24” ROS – ???. Handrail is hard to
attach and align. Handrail may be
maintenance problem.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansSingle LogSingle Log
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansNail-Lam Longitudinal Slab
Spans 12 to 30 feet. Best for widths < 8’. Materials 2x6 to 2x14. ROS - ??? Labor intensive. Materials less expensive but
labor is higher. Good for sites short
distance from trailhead but not accessible for equipment
Moderate maintenance. Handrail difficult to attach.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansNail Laminated SlabNail Laminated Slab
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Prefabricated Steel
Truss Spans > 60’ (Standard
Plans limited to 100’) Any width. ROS – ??? Requires heavy
equipment. Too heavy for economical
use of helicopters. Requires manufacturer
design and shop drawings.
Low maintenance.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansPrefabricated TrussPrefabricated Truss
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Packable Bridge
Span 36 feet or less. Any width. ROS - ??? Alternative to
helicopter use. Expensive materials. Labor intensive. More difficult to build. Increased
maintenance.
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard PlansPackable BridgePackable Bridge
R1 Trails Project PreparationR1 Trails Project Preparation
Trail Bridge Standard PlansTrail Bridge Standard Plans• Abutment Details
Sill designs - Spill-thru Keep away from stream
edge. Not applicable if scour
issues. Do not stack sills to gain
height. Place on geocell, gabion,
or concrete pad. Need to be site adapted.
R1 Trails Project PreparationR1 Trails Project Preparation
Timber Cribbing & Rock GabionsTimber Cribbing & Rock Gabions
Sill on Gabion
Sill on Timber crib on geocell
R1 Trails Project PreparationR1 Trails Project Preparation
Others Trail Bridge TypesOthers Trail Bridge TypesTimber Truss
Spans 50 to 100+ feet.
Any width ROS – ??? Labor intensive. Difficult to build Moderate
maintenance. Can be built with
semi- primitive tools or heavy equipment.
R1 Trails Project PreparationR1 Trails Project Preparation
Others Trail Bridge TypesOthers Trail Bridge TypesTimber TrussTimber Truss
R1 Trails Project PreparationR1 Trails Project Preparation
Others Trail Bridge TypesOthers Trail Bridge Types• Suspension
Bridges Spans > 100 feet Up to 8 feet. ROS – ??? Very difficult to
build. Very high
maintenance. Very high cost
R1 Trails Project PreparationR1 Trails Project Preparation
General GuidanceGeneral Guidance
Trail Types Clear width Rail HeightHiking 4’ 42”
Mountain Biking 4’ 54”
Pack and Saddle 5’ w/o rail6’ w/rail
54”
Cross Country Skiing 6’ 42”
Snowmobile 6’ Site specific
Motorcycle 42” 42”
ATV 50” 27”
R1 Trails Project PreparationR1 Trails Project Preparation
General GuidanceGeneral GuidanceRailing – Are they needed?
Proposed manual direction says: In general, rails shall be required for all trail and pedestrian
bridges. However, railings may be eliminated and potentially curbs substituted for rails when an appropriate analysis as described below has been completed:
An analysis has identified and evaluated the potential users and determined that the potential hazards along the trail are the same or greater than that of a bridge without a rail. The analysis shall include the possibility of using a rail on only one side of the bridge. In general, rural and urban ROS settings are likely to have small children and less experienced users. Thus, a railing is warranted in most instances. In backcountry or wilderness settings, where users are normally more experienced, rails may not be needed.
R1 Trails Project PreparationR1 Trails Project Preparation
General GuidanceGeneral Guidance Pettibone to left, Goat to
below on NP. Selway wilderness.
R1 Trails Project PreparationR1 Trails Project Preparation
General GuidanceGeneral Guidance
Dome Mtn. Kootenai. Cabinet Wilderness
No Handrail!
R1 Trails Project PreparationR1 Trails Project Preparation
Type ROS Spans Equipment Maint. CostSawn Stgr. 10’ to 40’ Light Low Low/Med
Log Stgr. 10’ to 45’ Light/Med Low Low/Med
GL Stgr. 25’ to 60’ Medium Low Low/Med
GL Slab 10’ to 35’ Light Low Low
Single Log 10’ to 45’ Primitive/Light Low Low
NL Slab 12’ to 30’ Primitive/Light Moderate Medium
Steel Truss > 60’ Heavy Low High
Packable < 36’ Primitive/Light Moderate High
Tbr. Truss > 60’ Light/Heavy Moderate High
Suspension > 100’ Medium High High
General GuidanceGeneral Guidance
R1 Trails Project PreparationR1 Trails Project Preparation
Wilderness Trail BridgesWilderness Trail Bridges
• Unique What is
appropriate? What can you
build? Is a bridge
needed?
Bob Marshall Wilderness
R1 Trails Project PreparationR1 Trails Project Preparation
Wilderness Trail BridgesWilderness Trail Bridges
• Design Process• Add conceptual
design before Project Scope
• Need alternatives Bridge Type Construction methods Materials Costs
Conceptual Design
Project Scope
Location/Survey
R1 Trails Project PreparationR1 Trails Project Preparation
Wilderness Trail BridgesWilderness Trail Bridges
• Minimum Tool analysis.• Use of helicopters• Force Account or Contract.• Logistics!!
Wilderness bridges are the most complicated and expensive. Need special attention.
R1 Trails Project PreparationR1 Trails Project Preparation
Helicopter UsageHelicopter Usage• Helicopter contracts
Type I – (Heavy) Sky cranes, etc Can pick up to 25,000 lbs. On call contract $9000/hour Must come out of West Coast. Mob costs prohibitive.
Type II – (Medium) 5000 to 12,000 lbs. On call contract $4500/hour Several in Montana, but not readily available.
R1 Trails Project PreparationR1 Trails Project Preparation
Helicopter UsageHelicopter Usage
• Helicopter contractsType III –( Light)
Can pick up to 5000lbs. On call contract $1800/hour For up to 3000 lbs, readily available.
Need to plan ahead and try to coordinate with other work in the area to lower costs.
R1 Trails Project PreparationR1 Trails Project Preparation
Helicopter UsageHelicopter Usage
• Helicopter Use - best value?Small helicopter
More trips More on-site labor (fly one stringer at a time)
Big Helicopter Less trips. Less on site labor (fly in entire bridge
superstructure)
R1 Trails Project PreparationR1 Trails Project Preparation
Preservative TreatmentsPreservative Treatments
• What is life expectancy of permanent bridge?
• Life of untreated material? 15 to 20 years
• Life of treated material? 50 + years
R1 Trails Project PreparationR1 Trails Project Preparation
Preservative TreatmentsPreservative Treatments
• Treated vs Untreated. Manual Direction fpr
permanent structures design life of 50 yrs
However, exceptions are made.
Who decides? Forest
Treated material is strongly recommended.
Papoose Creek on Clwt NF
R1 Trails Project PreparationR1 Trails Project Preparation
Preservative TreatmentsPreservative Treatments
• Protect the integrity of Treatment. Cutting ends, drilling
holes, all ruins treatment.
• Field treatments have limited success.
• To apply field treatments, person needs training and certification. Hassle!Blue Sky Bridge on Ktn NF
R1 Trails Project PreparationR1 Trails Project Preparation
Preservative TreatmentPreservative Treatment• Any laws against
Treatment? Only 1 by EPA Can not use CCA in
members in direct contact with peoples skin.
No others.• However, do we
want oily treatment on handrails?
R1 Trails Project PreparationR1 Trails Project Preparation
Preservative TreatmentPreservative Treatment• Options
Substructure, stringers, deck, curbs
Penta, Copper Naphthenate
Handrail Treated – many
choices Untreated –
redwood or Red Cedar
• Changing constantlyIron Springs - DPGL