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Timber: trends in availability, sustainability and durability
Mick Stephens, Chief Executive, Timber Queensland
9th Australian Small Bridges Conference Gold Coast, April 2019
Jimmy's Gully Pedestrian Bridge, HarlinQld, Timber Restoration Systems
Mega-trends for timber bridges (+)
• wood availability
• innovation
• environmental recognition
• global certification
• cost-effectiveness and durability
• Wood Encouragement Policies
• health benefits
• renewable
• carbon-friendly
• innovative
• versatile
• cost-effective
Changing perceptions:
timber can be the solution
when it comes to bridges
Demand for timber
Product 2012-13 2029-30 2049-50
Sawn timber (Mm3) 5.1 6.0 6.5
Wood based panels (Mm3) 1.7 3.1 4.3
Paper (Mt) 3.6 5.8 7.1
Source: ABARES
Long-term consumption forecasts: Australia
Queensland consumption trends (previous 10 year average to 2013)
Product Consumption Production Imports
Sawn timber (m3) 1,200,000 850,000 350,000
• consumption projected to be stable to 2024 (BIS Shrapnel 2015)
• population and building growth will drive long-term demand
• mature industry
• able to respond to market needs
Wood availability: plantation regions
Wood availability: harvest levels
Source: ABARES
• proportion of harvest is exported as log or woodchip (7.3 Mt)
• balance made up of imported timber products (~2M m3)
Production 2016-17
Sawn timber 4.6 Mm3
Paper 3.2 Mt
Panels / EWPs 1.7 Mm3
Total log 33M m3
Native HW 4 Mm3
Plantation HW 11 Mm3
Plantation SW 17 Mm3
Area
Plantations 1.97 Mha
Native forest 36 Mha
Source: ABARES. Commercial native forest area where harvesting permitted.
Growth policy• Australian Government announced $20m
Forest Industries Plan in 2019
• aim to plant 1 billion new timber production trees by 2030
• R&D into productivity of existing plantations as well as new plantings
• increase domestic supply over medium term
• large potential to increase hardwood supply from PNF (e.g. Queensland, northern NSW)
• sawlogs + thinnings(smaller diameter logs) for solid girders, poles and EWPs
• > +100,000 m3 extra sawlog per year
• 1.8 Mha with commercial potential
Additional sawlog volume from improved PNF
silviculture & extension (South-East Queensland)
Private native forestry
Source: Venn & Francis (unpublished, QDAF/FWPA supported project)
Innovation: engineered timber
Cross Laminated Timber Laminated Veneer Lumber Glulam
Plywood
Innovation: wood processing advances
• improve recovery and value for EWPs
• rotary-veneer produced from low quality / smaller diameter logs
• application for new timber products
• lower cost processing technologies
Source: QDAF
Spindleless lathe & composite products, QDAF research laboratory, Salisbury
Innovation: tall buildings
• 25 King Street, Lendlease, Brisbane
• Tallest timber office building in Australia
• 9 storeys
• parallels with bridges
• growing global use of EWPs in tall buildings
• changes in regulations and codes for these products (UK, USA, Europe, Canada, Australia)
• strength, straightness and stability
• supplement solid timbers for girders, decks
• EWPs have same potential in bridge construction as for tall buildings
DiversificationSplinter Creek, South Burnett Qld, NiuBridge Systems
Forest sustainability: certification
• total area certified is 8.8 Mha
• Chain of Custody certificates = 189 (PEFC) and 258 (FSC)
Cumulative global forest area managed under major certification schemes
Source: UNECE / FAO (2016)
• 30% of world roundwood from certified forests
• increased 30-fold since 2000
Relatively easy to source certified timber products
Australia
Environmental benefits
Although some CO2 is released during the sawing and milling of timber, the net effect is that 8.3kg of CO2 is absorbed during both the growth and production of timber
Source: “Which is Better? Steel, Concrete or Wood”; Glover. J., Sydney University, 2001
GHG impacts: construction sector
Source: Yu et al (2017). The carbon footprint of Australia’s construction sector.
• construction makes up 18% of Australia’s carbon footprint
• 90.4 Mt in 2013 (499 Mt for Australia economy-wide), roads and bridges 9Mt
40%
21%
8%
31%
Embodied GHG from construction
Electricity
Materials
Construction
Other
Cement, concrete & brick were 39% of materials carbon footprint
Construction services includes concreting, demolition etc.
GHG impacts: timber benefits
• replacement of reinforced concrete with CLT in buildings generates lowest CF particularly when sequestration included
• what about bridges?
Source: Teh et al (2017). Replacement scenarios for construction materials based on economy-wide hybrid LCA.
• modelled GHG reduction for Australian construction
• switch to RE
• replace concrete with CLT or geopolymer at 2.4% pa
Emissions savings: bridge case study (Norway)
Both used stress laminated timber (SLT) decks and met load demand
• Case 1: 31% less emissions (1410 versus 2032 tonnes CO2e)
• Case 2: 35% less emissions (saved 13 tonnes CO2e)
Source: Gustafsson & Hagman (2017). Comparable life cycle assessment of concrete and timber road bridge desk designs. Conference Proceedings ICTB.
Case 1: Oppstadaa bridge. New timber arch and deck for large highway bridge, 120m span and 21m width.
Case 2: Vippa bridge. Concrete arch with concrete deck and steel beams. Replacement of degraded deck, 50m span and 6m width.
Durability and service life
• AS1604 well-established hazard classes
• fit-for-purpose
• service live depends on treatment, location and use
• 25 to >100 years
Source: FWPA Timber Service Life Design
Durability and service life • timber bridge service life can be extended through regular maintenance
• good design will reduce risk (e.g. water ingress)
• ease of replacement and/or repair well suited to short or long term needs
Source: FWPA Timber Service Life Design. Same principles for bridges.
Under deck connections, TRS
Versatility
• suits prefabrication
• modular
• light, transportable
• fast installation
• easily replaceable and/or repaired
Cowra Bridge, HQPlantations, Qld
Single lane bridge preassembled, TRS
Cost-effectiveness
• around 40,000 timber bridges across Australia
• proven case-studies of effective repair and/or replacement with timber
products and good design
• Cassowary Coast LGA replacement program ($ savings)
• numerous examples across Australia
Rakaia Gorge NZ
PNGFP NiuBridgeSystems
Mackay bridge (TRS)
Boundary Road bridge, Qld (TRS)
Boundary Road bridge, Qld (TRS)
Emu Creek, Niu bridge systems
Monash University student accommodation, Frankston (Multiplex)
CLT constructionSix levels, 150 unitsNet zero carbon strategy
• CLT construction
• Six levels, 150 units
• Carbon neutral strategy (private sector)
JUST COMPLETED
March 2019
Health
benefits
• researchers
• architects
• designers
• builders
• planners
• community
• bridges play an important role in urban and rural biophilic design (e.g. road, pedestrian, rail etc.)
Bridges: why wood?• renewable
• sequesters + stores carbon
• low embodied energy
• strong, light weight, fast
• cost-effective
• WEPs & sustainability policies
• biophilic benefits
• these trends need to be considered in the market
GBCA Green Leader of the Year. Source: Timber enews.
Adam Jones, Structural Engineer, TPC Solutions