Crossings : newsletter of the Wood in Transportation Program

10 Pages·2001·0.85 MB·English

by  National Timber Bridge Initiative (U.S.)

Historic, Archive Document
Do assume
not content reflects current
scientific knowledge, policies, or practices.

aTG365
C76
•
Issue 40 Summer 2001
Overview of the National Wood In
Transportation Program's Portable
Timber Bridge Activities
In This Issue One segment of the National Wood In Transportation (NWIT)
programhasbeentodeveloppartnershipsthatleadtothedevelopment
and demonstration ofsimple, dependable, and economical portable
OverviewoftheNationalWood In timber bridge designs used for timber harvesting operations and
Transportation Program'sPortable other temporary stream crossing applications. One ofthe primary
Timber Bridge Activities 1 purposes for these projects is to find solutions for minimizing the
environmentalimpactstostreamsduringtimesoftemporarycrossings.
Results oftheNinth National Timber Todate,theprogramhasfundedeightportabletimberbridgeprojects.
Bridge StudentDesign Competition 2 Threeoftheseprojectsarehighlightedbelow. Inaddition,theUSDA
Forest Service has developed a lightweight portable timber bridge
design for use on skidder trails. The enclosed fact sheethighlights
NewPublications: this effort.
Design ofWood Highway Sound Portabletimberbridgeprojects:
Barriers 3 R
TheDevelopmentandTestingofGlulamPortable Timber
—
FieldPerformanceofTimberBridges Bridge Designs Auburn University, Department of
21. Humphrey Stress-Laminated Agricultural Engineering, Auburn, AL
T-BeamBridge 4
The objective ofthe work at Auburn was to develop timber
bridge designs for temporary stream crossings such as those
Analysis ofThermal Change in Stress-
encounteredonloggingroadsandskidtrails. Cooperatingwith
LaminatedTimberBridgeDecks 4
the USDA Forest Service and with several industry partners,
Auburn developed and tested several different designs of
portablebridgesusingglued-laminatedtimbers. Thesebridges
include several prototypes for truck traffic and one for off-
Inserts: highwayvehicles like wheeled skidders. These bridges have
APortable SkidderTimberBridgeDesign been tested and monitored for performance and longevity in
typicalforestharvestingoperations. Inadditiontoconstructing
and monitoring the prototype designs, test data were used to
develop information that can be used to help in the design of
future portable timber bridges. Currently, at least one
manufacturer of glued-laminated timbers is fabricating and
Continued Page 2
Visit our website at www.fs.fed.us/na/wit
Overview of Portable Timber Bridge Results of the Ninth National
Activities . . . continuedfrom page 1 Timber Bridge Student Design
Competition
marketing these types of portable bridges. For
additional information about this project, contact:
Nine teams ofstudents from universities acrossthe United
SteveTaylor,AuburnUniversity,at334-844-3534,
States matched wits during the Ninth National Timber
or visit the following website: http://
www. eng. auburn.edu/users/staylor/ Bridge Student Design Competition. Open to student
chaptersoftheAmerican SocietyofCivilEngineers(ASCE)
timberJbridges.html.
and Forest Products Society (FPS), the competition was
M The Development and Testing of Stress- made possible by a grant from the USDA Forest Service,
LaminatedPortable TimberBridgeDesigns— Wood In Transportation program. The Southern Pine
WV Council ofthe Southern Forest ProductsAssociation, Unit
West Virginia University, Morgantown,
Structures LLC, and Willamette Industries provided
The objective ofthis project was similar to the additional financial support. Southwest Mississippi
Resource Conservation and Development (RC&D), Inc.,
project objectives listed previously, except the
basic design conceptused stress-lamination. An coordinated the annual competition.
effective bridge design was developed and
demonstrated. A business in Morgantown is Each team designed, constructed, and tested their bridges
on their home campus, then submitted documentation of
currentlymanufacturing and marketingthistype
their activities and results to a panel ofjudges for review.
of bridge in 30-foot and 40-foot lengths. For
The competition was conducted online via the Internet.
informationaboutthiseffort,contactCurtHassler,
ClearCreekCrossings,LLC, at304-291-3962. rEeasculhts,teaanmdpwroajsecrtehqiugihrleidghttsoonpotshteWdeesbigantwdwrwa.wimnsgrsc,d.toersgt
(www.msrcd.org/bridge.htm). To view details of
A publication titled, Portable Timber Bridges:
competition results andto access each entry in its entirety,
An Eco-friendly Solutionfor Stream Crossings,
clickon“2001 Competition Results.”
documentsthis effort. It is availablethroughthe
National Wood In Transportation Information Winner ofthe Best Overall Design Award sponsored by
Center at 304-285-1591 and request publication WillametteIndustrieswastheMississippiStateUniversity
number WIT-02-0038. The publication can be ASCE Chapter. Their design used multiple members in
viewed on the Web at http://www.fs.fed.us/na/
both tension and compression to minimize weight and
wit/pdf/portab-1.pdf. deflection. A 1-inch by4-inchtongueandgroovedeckwas
M supported bysevenglued-laminated longitudinal stringers.
New York City Wat—ershedForestry Temporary Four steel cable assemblies were added to limittension in
Bridge Program Watershed Agricultural the bridge. All wood members were southern pine treated
NY
Council,Walton, with bromated copper arsenate at 0.40 pounds per cubic
foot. This entry also placed second in Best Deck
The objective ofthis project was to encourage Performance andsecondin MostAesthetic Design. The
the adoption of temporary bridges as a timber Teamreceivedcashawardstotaling$2,350fortheirefforts.
harvest best management practice in the New
York City watershed. Emphasis was placed on TopmoneywinnerwastheUnitedStatesMilitaryAcademy
thedevelopmentand/ordemonstrationofbridges ASCE Chapter with awards totaling $2,500. Their entry
usedforskiddertrailsandhaulroadapplications. placedfirstin BestDeckPerformanceand Most Practical
To date, a skidder bridge design has been Design and second place in Best Support Structure
developed and demonstrated. Approximately PerformanceandtheWillamette Industries BestDesign.
three small businesses are currently Theirdesign featured atransversedeckof2-inch by6-inch
manufacturing and marketing these types of CCA-treated southern pine ship-lapped and edge-glued.
bridges. At least one stress-laminated portable The deck was supported by three longitudinal parallel
timber bridge for use on haul roads has been trusses builtofsouthernpine2-inch by4-inch lumberusing
demonstrated and promoted. For additional standard nail plates. Theirgoal was practicalityand speed
information about the program, contact Justin ofconstruction, combined with strength and lightweight.
Perry, Watershed Agricultural Council, at 607-
865-7790 or visit the following website:
http //www. nycwatershed. org/forest,htm.
:
Continued Page 3
2
Ninth National Timber Bridge Student Design Net deck deflection for the three bridges that met the
Competition continuedfrom page 2 maximumallowabledeflectionofdeckspandividedby400
. . . averaged 74percentofmaximumallowable. Percentnon-
wood materials in the bridges averaged 8.5 percent;
maximum percent non-wood materials allowed was 25
TheASCEChapterofWashingtonUniversityatSt. Louis percentbyweight. Atotalof68studentsspent 1,583 hours
was another bigwinner, receiving $2,000 forfirstplace in
Best Support Structure Performance, second in Most onthecompetition,competingfor$10,000 inprizes. Judges
forthecompetitionwereBertLovell,WillametteIndustries;
Practical Design,and thirdin Best Design and Best Deck Nelson Hernandez, USDA Forest Service; and Shannon
Performance. Theirtwincomposite I-beamstructureused McCarty, USDANatural ResourcesConservation Service.
CCA-treatedsouthernpinewith2-inchby6-inchtransverse
stiffeners spanned by a longitudinal deck ofsouthern pine
BennieF. Hutchins
2-inch by 6-inch planks. RC&D
Coordinator
Southwest Mississippi RC&D, Inc.
Thefinal first-place entrywasproducedbySanJoseState
University's ASCE Chapter. Their above-deckparallel-
chordtrusses combined with longitudinal 2-inch by6-inch
Douglas fir deck caughtthe eyes ofall threejudges to win
first place as Most Aesthetic. Adding two third place
awards in Most Practical Design and Best Support
Structure broughttheirtotal awards to $1,350.
TheVirginiaPolytechnicInstituteandStateUniversity's
Forest Products Society Chaptercapturedfirstplace for Design of Wood
the Most Innovative Design for their arch-suspension
Highway Sound
bridge. Clarkson UniversityandOklahomaStatesettled
for a second place tie in this category. Barriers
Other teams competing in the competition included
Merrimack College ASCE and Rose-Hulman Institute of As new and existing United States residential areas and
TechnologyASCE. high volume highways continue to intermingle, traffic
noise abatement procedures continue to be important.
For a complete review of competition results and each This study investigated the acoustic effectiveness, public
individualentry,gotowww.msrcd.organdfollowthe links. acceptance, and structuralrequirementsofvariousdesigns
Results of 2000, 1999, and 1998 competitions are also and types of sound barriers. In addition, the acoustic
postedonline. The2002 Competition begins in September effectiveness of a prototype sound barrier is reported.
2001 with rules being posted on the website in late August Results are presented on the acoustic effectiveness from
2001. For additional information, contact Southwest in situ measurements of one cement bonded composite
Mississippi RC&D, Inc., 747 Industrial Park Road, NE, panel barrier and four precastconcrete, two plywood, two
Brookhaven, MS39601. Phone: [phone], Fax: 601- glued-laminated, and three post and panel barriers. The
835-0054,e-mail: [email protected], orvisitthe Wood research on public acceptance ofsound barriers focused
In Transportation website at www.fsfed.us/na/wit. ontheperceptionofvisual compatibility. Basedonresults
from semantic-differential and individual ratings, wood
The competition's objectives areto promote interest inthe andconcretebarrierdesignswereperceivedtohavefavored
use ofwood as acompetitive bridge construction material, “rural” qualities. Data collected during the research on
to generate innovative and cost-effective timber bridge acoustic effectiveness and public acceptance were used to
design techniques, and to develop an appreciation ofthe develop structural requirements and construction details
engineering capabilities of wood among future for a prototype wood sound barrier. The prototype wood
transportation and forest products engineers. Following sound barrierprovided insertion lossesof15 dB orgreater,
the competition, most ofthe bridges are placed into use as exceedingthe 10-dBacceptableperformanceforahighway
trail bridges for pedestrians, horses, snow mobiles, etc. sound barrier.
Thetestbridgeswere 13 feet longand4 feetwide andwere To obtain a copy, please contact the National Wood In
loaded with a test weight ofapproximately 4,500 pounds. Transportation Information Center at 304-285-1591 and
Average weight ofthe bridge models was 722 pounds. At requestpublicationnumber WIT-02-0062orvisitthe Wood
full loading, maximum bridge deflection ranged from4.42 In Transportation website at www.fsfed.us/na/wiV, click
mmto9.91mm. Maximumallowabledeflectionwas 10 mm. on “New Publications Available”.
3
,
NEW
PUBLICATIONS
Field Performance Analysis of Thermal
of Timber Bridges Change in Stress-
21. Humphrey Stress-Laminated Laminated Timber
T-Beam Bridge Bridge Decks
TheHumphreyBridgewasconstructedduringthesummer As the timber bridge design has evolved, some engineers
and fall of 1993 in Cattaraugus County, New York. The have been concerned about the integrity of the stress-
bridgeisasingle-span,stress-laminatedT-beamstructure laminatedsystemincoldclimates. Thestructuralintegrity
m
thatmeasures 14.1 (48.6ft)longand 10.2m(33.5ft)wide. of a stress-laminated bridge depends on the level of
Performance ofthe bridge was monitored for 35 months, interlaminarcompression(betweenthewoodlaminations).
beginning approximately eight months after installation. Temperature change can cause material shrinkage, which
Monitoringinvolvedgatheringandevaluatingdatarelative could lead to substantial performance problems based on
to the moisture content ofthe wood components, force material mechanics andthe nature ofthe stress-laminated
level of the stressing bars, and behavior of the bridge system. In this study, to determine the effects ofthermal
under static load conditions. In addition, comprehensive changeoninterlaminarcompression,fourstress-laminated
visual inspections were conducted to assess the overall timber decksections were putthrough awarm-cold-warm
conditionofthestructure. Basedon fieldevaluations,the cycle. Variousinterlaminarstresslevelsandthreemoisture
bridge is performing well, with only a few minor content levels were tested. Results showed that
serviceability issues. interlaminarcompressioninstress-laminateddecksofthis
sizewasnotaffectedbyextremelycoldtemperatureswhen
To obtain a copy, please contact the National Wood In the moisture content was less than 19 percent and when
Transportation Information Center at 304-285-1591 and initial barforce was sufficient.
request publication number WIT-06-0042, or visit the
WoodInTransportationwebsite atwww.fs.fed.us/na/wit; To obtain a copy, please contact the National Wood In
clickon“NewPublications Available”. Transportation Information Center at 304-285-1591 and
request publication number WIT-06-0041 or visit the
Wood In Transportation website at www.fs.fed.us/na/wit,
clickon “New PublicationsAvailable”.
Article contributions, questions, or comments may be sent to Ed Cesa, Program Coordinator, National Wood In Transportation
Information Center or Mr. Chris Grant, Program Assistant, USDA Forest Service, 180 Canfield Street, Morgantown, WV 26505; Phone:
[phone]; FAX: [phone], or e-mail [email protected]. A change ofaddress may also be submitted to [email protected]. For
publication requests, e-mail [email protected].
Crossings is a service ofthe USDA Forest Service, Northeastern Area, State and Private Forestry, and is distributed quarterly to individuals
and organizations without fee. Products, designs, and treatments mentioned by contributors from outside the USDA are not necessarily
endorsed by the USDA, nor do statements made herein reflect the policy of the USDA. In all cases, consult with appropriate professional
and state or local regulatory agencies for conformance to applicable laws and regulations.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, sex,
religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with
disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s
TARGET Center at [phone] (voice and TDD).
To file a complaint ofdiscrimination, write USDA, Director, Office ofCivil Rights, Room 326-W, Whitten Building, 1400 Independence Avenue, SW,
Washington, D.C. 20250-9410 or call [phone] (voice and TDD). USDA is an equal opportunity provider and employer.
4
.
WIT-02-0061
A
Portable Skidder Timber Bridge Design
The USDA Forest Service San Dimas Technology and Development Center (SDTDC) and the Wood In
Transportation (WIT) Program have developed a portable/temporary skidder bridge to cross drainages for field
harvesting equipment. Its length is 16 feet, and width is 12 feet. It is constructed using three 4-foot-wide
preconstructed laminated panels. The exterior panels have 8-inch wide by 8-inch high curbs making the travelway
width 10 feet 8 inches. The bridge is designed to carry a 27,000-pound axle load, which equates to a Caterpillar 525
Skidder with an 8,000-pound grapple load. One major goal ofthis project was to design a lightweight easy to install
bridge that would aid in minimizing erosion and sedimentation at stream crossings.
The panels are preassembled, and field equipment, such as a skidder can be used to install the bridge. The bridge
rests on 4-inch by 8-inch sills. Each sill has guide plates to secure the panels in place.
Acceptable species and grades are shown in table 1. Any species ofwood may be used providing its unfactored
bending strength is at least 875 pounds per square inch. SDTDC evaluated bolted panels, but the panels can be glued
or nail laminated (see note 1).
This bridge is structurally adequate for 3- or 5-axle log trucks. However, due to its narrow width, minimal curb
system, and large live load deflection, log truck traffic should be limited to occasional trucks operating at low speeds.
Dynamic effects caused by rough approaches, or bumps at the ends ofbridges, can significantly increase wear and
damage to bridges. Approaches to bridges should be initially graded and maintained at a relatively smooth and level
surface.
This project was completed by: James R. Bassel, Project Leader, USDA Forest Service, San Dimas, CA
Merv Eriksson, Structural Engineer, USDA Forest Service, Missoula, MT
For additional information, visit the Wood In Transportation website at w'vrvv.fs.fed.us/na/wir or call the National
Wood In Transportation Information Center at [phone]
USDAForestService San DimasTechnology Wood InTransportation
and DevelopmentCenter
FIELD EVALUATION
The Homochitto National Forest in Mississippi evaluated this design. The Forest used red oak common to the area. The bridge
has been used on three different sales and has carried more than a million board feetoftimber. The Forest was pleased that the
drainages were notdisturbed, and the contractor was able to save time by traveling over the drainages rather than around them.
Two men assembled the bridge panels in two days. Installation ofthe bridge panels at the site takes two men 30 minutes using
standard field equipment.
Approximate Material Cost: Forest Contact:
Wood $ ,500.00 Lee Dunnan
1
Hardware 150.00 National Forests in Mississippi
Total $ ,650.00 Homochitto Ranger District
1
Rt. 1, Box 1
Meadville, MS 39652
[phone]
SKIDDER BRIDGE MATERIAL LIST
For Three Bolted 4-foot Panels using 4-inch by 8-inch Timbers
Timber
Note: The design requires a bridge depth of8 inches. Any width timbers that have that depth can be used (e.g., 2-in by 8-in,
3-in by 8-in, etc.). SDTDC used 4-inch by 8-inch timbers. Exterior laminations must be4 inches thickdue to countersinking.
40 4-in by 8-in by 16 feetrough sawn timber (see Table 1)
2 4-in by 8-in by 12 feet rough sawn timber for sills (can use 16 feet length)
Hardware for 4-foot panels
24 3/4-inch by 4-foot rods with threads, 6 inches each end
48 3/4-inch nuts (heavy hexagon)
48 3/4-inch malleable iron washers
Hardware for curbs Hardware for sill
8 3/4-inch by 18-inch bolts 12 3/4-inch by 10-inch lag bolts
8 3/4-inch nuts (heavy hexagon) 12 3/4-ioch malleable iron washers
16 3/4-inch malleable iron washers
Total Materials for Skidder Bridge
42 4-in by 8-in by 16 feet rough sawn timber (using 16 feet for sills)
24 3/4-inch by 4-foot rods with threads, 6 inches each end
r ~
8 3/4-inch by 18-inch bolts
1
56 3/4-inch nuts (heavy hexagon)
76 5/8-inch malleable iron washers
12 3/4-inch by 10-inch lag bolt
TheU.S.DepartmentofAgriculture(USDA)prohibitsdiscriminationinallitsprogramsandactivitiesonthebasisofrace,color,nationalorigin,sex,religion,age,disability,political
beliefs,sexualorientation,ormaritalorfamilystatus. (Notallprohibitedbasesapplytoallprograms.) Personswithdisabilitieswhorequirealternativemeansforcommunicationof
programinformation(Braille,largeprint,audiotape,etc.)shouldcontactUSDA’sTARGETCenterat(202)720-2600(voiceandTDD).
Tofileacomplaintofdiscrimination,writeUSDA,Director,OfficeofCivilRights,Room326-W,WhittenBuilding, 1400IndependenceAvenue,SW,Washington,D.C. 20250-9410
orcall(202)720-5964(voiceandTDD). USDAisanequalopportunityproviderandemployer.
************************
TheUSDAForestServiceherebygivesnoticethattheinformationhereincontainedshallnotcreateanywarrantyexpressedorimplied. Thepersonororganizationusingthis
informationwaivesandrelinquishesanyandallclaimsagainsttheUnitedStatesofAmerica,itsofficers,employees,andprojectcooperators,foranyloss,damage,personalinjury,or
deathincidentto,oroccurringasaconsequenceof,theusethereof.
September2001
mm
USE 3/4*0 x THREADED ROD
WITH MALL IRON WASHERS
3/4* 0x18" BOLTS WITH COUNTERSINK MALL IRON WASHERS
MALL. IRON WASHERS AND NUTS, AND CUT ROD OFF
FLUSH WITH OUTSIDE OF PLANK FACE
DRILL 1*0 HOLE FOR 3/4V RODS
USE 3/4"0 x THREADED ROD
WITH MALL IRON WASHERS
COUNTERSINK MALL. IRON WASHERS
AND NUTS, AND CUT ROD OFF
FLUSH WITH OUTSIDE OF PLANK FACE
DRILL 1"0 HOLE FOR 3/4"0 RODS
SKIDDER BRIDGE
SECTION THROUGH DECK BEAM NEAR ABUTMENT Designed By: Dot,: 2/9/2001 DRAWING NuT
—
- r
SKIPPER BRIDGE NOTES:
as r3O 11//44"09 CCUOUUNNITtERSUNK HOLES 2" DEEP TYP. /-1"0 HOLES
—V • 4 -•4— fr— 1Ex.teBrRiIorDGEpanPeAlNsELsSh:all Thharveee 8p-ainnelcsh, w4i8deinbcyhe8s-iwnicdhe hsihaglhl gbueidefabcruircbastedasfrsohmown4.—inTchhethpiacnkelbsy a8re—isnchhowwnidbeolltaemdintaotgieotnhse.r.
7 SPS. O 2’-0" - 14-0*
V,.,. The panels can also be glued laminated or nail laminated. If glued laminated, the panels shall be fabricated in
EXTERIOR PLANK ”A” (6 required) conformance with AASHTO Ml68 and ANSl/AITC A190.1 and shall be manufactured to an Industrial appearance using
wet-use adhesives.
PLANK A is the exterior lamination for each panel edge. It has 8 countersunk
holes through its wide face.
If nail laminated, each lamination shall be nailed using 10-inch deformed shank bridge spikes having a minimum
shank diameter of 3/8" in pre-drilled %" diameter holes. The spikes shall be spaced at 12 inches and staggered at
2 inches from the top and bottom of the planks.
-7/8"0 HOLES
2. WOOD SPECIES AND GRADES Any species of wood may be used providing its tabulated, or unadjusted, allowable
:
fsfP bending stress is not less than 875 pounds per square inch. Examples of acceptable species and grades are shown
S’-7*' 5'-7j- in Table 1. Expected use and expected life span should be considered when selecting a species. High volumes of
H skidded timber may require a hard, high—density species.
1-41 h--^-1^4 I— 4 H:zf 3. PRESERVATIVES: If the panels are to be used more than 1 or 2 years the timber should be pressure treated with
7 SPS. O 2‘—0" - 14*—0" Mananaapgpermoevnetd Pprraecsteircvaetsivfeo.r tThheeUstiinmgberTresahatleld bWeootdreaitnedAqiunatciconfaonrdmaWnectelanwdithEnAviWrPoAnmeCnlt4s.(soiIlnscoofnatracats) iasndpratchtiecaBl,estall
r| j PUNK | | lumber shall be cut, drilled, and completely fabricated prior to pressure treatment.
INTERIOR ”B” (2 required)
PLANK 8 is the second lamination from the outside in each exterior panel, it has 8 holes 4. DESIGN LOADS: These bridges are designed to carry a 27,000—pound skidder axle load. This skidder load
through its wide face and 4 vertical curb bolt holes through its narrow face. corresponds to a Cat 525 with an 8,000—pound grapple load. The bridge will also support an AASHTO Type 3 Truck
(3-axle dump truck), an AASHTO Type 3-S2 Truck (5-axle logging truck), an AASHTO HS 20 Truck (highway load
vehicle), or a track mounted vehicle having a load, per track, of up to 1,300 pounds per lineal foot. The bridge is
designed assuming exclusively the exterior panels carry all wheel and track loads. Larger skidder or track mounted
vehicle loads, or overweight trucks, will require redesigned panels or shorter spans.
—
— 5. DESIGN LIMITATIONS: Although the bridge is structurally adequate for standard highway 3- or 5-axle trucks,
—
'?B E 4 4 f 1 4—~1— bliemciateudsetoofoctchaesinonaarlrowtruwcikdsth,opmeriantiimnagl ahteiglhowt csuprebedssys(t1e0m,mialnesd plearrgeholuirve olroaldessd)e.flections; truck traffic should be
7 SPS. O 2’-0" - 14*—0"
^ 6. DYNAMIC LOADING: Dynamic effects caused by rough approaches, or bumps at the ends of the bridge can
INTERIOR PUNK ”C” (22 required) 3' significantly increase live loading, resulting in excessive wear and damage to the bridge. Approaches to bridges should
interior lamination. It has 8 holes through its wide face. be graded, and maintained as a level—riding surface.
7. HARDWARE: Malleable iron washers shall be used under all nuts and bolt heads unless the bolts are timber or
dome head. Bolts and lag bolts shall comply with the requirements of ANSI/ASME Standard B18.2.1—1981, Grade 2.
Any other steel components shall comply with ASTM A36.
•ti
8. INSTALLATION AND REMOVAL: Bridge panels may be prefabricated or assembled in place. Panels should be placed
on, and attached to, the leveling sills as shown. Foundations should be leveled and compacted as necessary to
3E3p3- provide a solid bearing surface for the leveling sill. Timber members and panels should be stored and handled so as
3 1/4'» COUNTERSUNK HOLES 2" DEEP not to damage the material. If damage d.o7e5s0-occur, exposed untreated wood should be field treated in accordance
- with AASHTO M 133.
14-1 h 1 1 h h-^-l hYF
7 SPS. O 2’—0* - 14*—0" TABLE 1 EX1T..75P0A-NEL
''~3' INTERIOR PUNK ”D” (6 required) SPECIES GROUPS VISUALGRADE* WEIGHT (Lbs)**
PLANK D is an interior lamination. It has 8 holes through its wide face and 2 Cottonwood Select Structural 1,750
countersunk vertical sill lag bolt holes through Its narrow face. Doug Fir/Larch No. 2 2,200-2.350 ona'
Hemlock/Fir No. 1 1,500-2,150 inforfl^»«
Red Maple No. 1 2,450
± Southern Pine No. 2 2,300-2,600 These
Spruce/Pine/Fir No. 1 1 2,050
/-!/&* HOLES 1 Western Woods Select Structural 2,350 itvuction-
—
/
sl
ROAD FACE SIDE * Lumber must be graded.
f-8j- 5-7J- 5-*i" ** Weights assume creosote treatment and
20% moisture content. SKIDDER BRIDGE
PLANK E Is the curb ClaUmiRnaBtion.PIUt NhaKs 4”ofEf"set(c4urRbEQbUoIlRtEDho)les through Its wide face. Weights vary in multiple species groups. ADpepsriogvneedd BByy:: . DDoatt.e:: 2. /9/2001 IDRSAHWEIENTG 2NO.OF 2