{{Short description|Bridge over the River Derwent in New Norfolk, Tasmania, Australia}} {{Use dmy dates|date=December 2023}} {{Use Australian English|date=December 2023}} {{Infobox bridge |name = Blair Street Bridge |image = New Norfolk, Tasmania.JPG |coordinates = {{Coord|42|46|44.68|S|147|3|24.03|E|region:AU-TAS_type:landmark|display=it}} |carries = {{AUshield|TAS|A10}} [[Lyell Highway]] |crosses = [[River Derwent, Tasmania|River Derwent]] |mainspan = {{Convert|116|ft|order=flip}}{{sfn|Department of Public Works Tasmania|1970|p=Appendix No.2}} |length = {{Convert|650|ft|order=flip}}{{sfn|Department of Public Works Tasmania|1970|p=Appendix No.2}} |width = {{Convert|41|ft|order=flip}}{{sfn|Department of Public Works Tasmania|1970|p=Appendix No.1}} |height = {{Convert|15|ft|order=flip}}{{sfn|Department of Public Works Tasmania|1970|p=Appendix No.1}} |clearance = |below = {{Convert|15|ft|order=flip}}{{sfn|Department of Public Works Tasmania|1970|p=Appendix No.1}} |locale = [[New Norfolk]] |location = [[Tasmania]], Australia |also_known_as = New Norfolk Bridge |maintained = [[Department of State Growth]] |followed = [[Bridgewater Bridge]] |design = [[Concrete]] and [[steel]] [[girder bridge]] |number_spans = 6{{sfn|Department of Public Works Tasmania|1970|p=15}} |piers_in_water = 5{{sfn|Department of Public Works Tasmania|1970|p=15}} |lanes = 2 |begin = 1971 |open = 1974 |replaces = Bridge Street Bridge {{small|({{circa|1930}}-1974)}}}}
The '''Blair Street Bridge''' is a [[concrete]] and [[steel]] [[girder bridge]] carrying the [[Lyell Highway]] through the township of [[New Norfolk]] across the [[River Derwent, Tasmania|River Derwent]] in [[Tasmania]], Australia. Serving as a vital transportation link in the township's infrastructure, the bridge features a [[single carriageway]]{{sfn|Department of Public Works Tasmania|1970|p=15}} with [[Grade separation|separated]] [[Shared-use path|shared-use pathways]] on both sides.{{sfn|Department of Public Works Tasmania|1970|p=10}} Completed in 1974, it is the fourth bridge to be constructed at New Norfolk, with the development aimed at withstanding valley floods before the establishment of the [[Meadowbank, Tasmania|Meadowbank]] [[weir]]s.{{sfn|Department of Public Works Tasmania|1970|p=3}}{{refn|group=note|The River Derwent severely flooded at New Norfolk on Saturday 23 April 1960. It was estimated this flood approximated a once in fifty year flood with a flow of 120,000 [[cusec]]s.{{sfn|Department of Public Works Tasmania|1970|p=12}}}}
==History== Generally known as the "New Norfolk Bridge", similarly placed bridges at New Norfolk have a rich history dating back to the early 19th century. The first wooden bridge constructed across the River Derwent at Bridge Street, near the contemporary Blair Street Bridge was completed in 1834.<ref>{{Citation | url=http://nla.gov.au/nla.news-article226505156 |title=Opening of the New Bridge at New Norfolk |newspaper=[[The Mercury]] |volume=XXXVI |issue=5924 |location=Tasmania, Australia |date=4 June 1880 |accessdate=29 December 2023 |page=3 |via=National Library of Australia}}</ref> This bridge was a pivotal development, connecting New Norfolk with the surrounding regions for the first time, facilitating transportation and trade. It was built under the direction of Assistant Surveyor General William Sharland, who owned the 1825 property known as Woodbridge. A toll was collected for crossing the bridge, which was eventually abolished in July, 1880.<ref>{{cite news |url=http://nla.gov.au/nla.news-article26500781 |title=Memories Of Old New Norfolk Revived By Octogenarian |newspaper=[[The Mercury]] |volume=CLXIX |issue=24,398 |location=Tasmania, Australia |date=19 February 1949 |accessdate=6 March 2024 |page=24 |via=National Library of Australia}}</ref> [[File:New Norfolk Toll House (22470510690).jpg|thumb|left|Constructed in 1841, the Toll House collected tolls until 1880.]] The River Derwent is highly susceptible to flooding<ref>{{Cite web |url=https://nre.tas.gov.au/Documents/Derwent.PDF |title=River Derwent Flood Data Book |page=6 |access-date=2024-03-07 |website=[[Tasmanian Government]] |last1=Land and Water Management Branch |archive-url=https://web.archive.org/web/20230927082119/https://nre.tas.gov.au/Documents/Derwent.PDF |archive-date=2023-09-27 |last2=Resource Management and Conservation Division |year=2000}}</ref> and over time, subsequent bridges in 1880<ref>{{cite news |url=http://nla.gov.au/nla.news-article226505156 |title=Opening Of The New Bridge At New Norfolk |newspaper=[[The Mercury]] |volume=XXXVI |issue=5924 |location=Tasmania, Australia |date=4 June 1880 |accessdate=7 March 2024 |page=3 |via=National Library of Australia}}</ref> and 1931<ref>{{cite news |url=http://nla.gov.au/nla.news-article29920988 |title=New Norfolk Bridge |newspaper=[[The Mercury]] |volume=CXXXV |issue=19,977 |location=Tasmania, Australia |date=18 August 1931 |accessdate=7 March 2024 |page=9 |via=National Library of Australia}}</ref> were built near the same location.<ref>{{Citation | author1=Alfred Mault | title=The River Derwent: Note upon the flood of 23rd September, 1884 | publication-date=1884-01-01 | url=https://trove.nla.gov.au/work/255476172 | access-date=6 March 2024}}</ref><ref>{{cite news |url=http://nla.gov.au/nla.news-article25231803 |title=The River Derwent In Flood At New Norfolk |newspaper=[[The Mercury]] |volume=CXLV |issue=20,537 |location=Tasmania, Australia |date=25 August 1936 |accessdate=6 March 2024 |page=9 |via=National Library of Australia}}</ref> The remnants of the first three bridges, including materials from the original 1834 structure and the later Victorian dressed-sandstone of the second bridge, can still be observed near Woodbridge at the end of Bridge Street.
Before the construction of the Blair Street Bridge, the town of New Norfolk relied on an aging steel and concrete bridge built in 1931 to facilitate transportation across the River Derwent.<ref>{{Citation |url=http://nla.gov.au/nla.news-article23810736 |title=New Norfolk Bridge |newspaper=[[The Mercury]] |volume=CXXII |issue=17,933 |location=Tasmania, Australia |date=17 April 1925 |accessdate=30 December 2023 |page=9 |via=National Library of Australia}}</ref><ref>{{Citation |url=http://nla.gov.au/nla.news-article29923911 |title=New Norfolk Bridge: Council Urge Completion, Old Bridge Removal |newspaper=[[The Mercury]] |volume=CXXXV |issue=19,997 |location=Tasmania, Australia |date=10 September 1931 |accessdate=30 December 2023 |page=3 |via=National Library of Australia}}</ref><ref>* {{Citation |url=http://nla.gov.au/nla.news-article29941722 |title=New Norfolk Bridge: Piles Strengthened |newspaper=[[The Mercury]] |volume=CXXXVI |issue=20,117 |location=Tasmania, Australia |date=29 January 1932 |accessdate=30 December 2023 |page=6 |via=National Library of Australia}}</ref> However, this bridge had become increasingly inadequate to meet the growing demands of modern traffic, characterised by substandard strength, limited width, and a load limit of {{convert|15|tonnes}} imposed in 1966.{{sfn|Department of Public Works Tasmania|1970|p=5}} Recognising the need for a more robust and efficient river crossing, plans were set in motion for the construction of a new bridge.{{sfn|Department of Public Works Tasmania|1970|p=5}}
===Construction=== Construction began in August 1971 and finished within two and a half years at a cost of A$900,000.<ref>{{Cite web |url=https://newnorfolknews.com/2018/06/foggy-conditions-in-historic-precinct/ |title=Foggy conditions in historic precinct |date=2018-06-15 |access-date=2024-03-07 |website=New Norfolk and Derwent Valley News |archive-url=https://web.archive.org/web/20240307085314/https://newnorfolknews.com/2018/06/foggy-conditions-in-historic-precinct/ |archive-date=2024-03-07}}</ref> Timber [[falsework]] aided river [[Pier (architecture)|pier]] access during construction.{{sfn|Department of Public Works Tasmania|1970|p=19}} Foundations use spread footings for abutments and driven [[Deep foundation|piles]] for piers, ensuring stability and minimising settlement risks. Design emphasises longitudinal and lateral stability for resilience against flooding and adverse weather. Aesthetic features, like minimalist balustrading and lighting, enhance the bridge's [[modernist]] appeal.{{sfn|Department of Public Works Tasmania|1970|p=18}} [[Hydraulic]] engineers evaluated factors such as river flow rates, water levels, and floodplain characteristics to determine the bridge's susceptibility to inundation during periods of high water.{{sfn|Department of Public Works Tasmania|1970|p=12}}
To minimise the risk of [[flooding]] impacting the bridge and its approaches, several design features were incorporated into the Blair Street Bridge project. These included raising the [[bridge deck]] to a predetermined elevation above anticipated flood levels, providing sufficient clearance for [[floodwater]]s to pass underneath without causing structural damage. Additionally, the bridge's abutments and piers were reinforced to withstand the [[hydraulic]] forces exerted by floodwaters.{{sfn|Department of Public Works Tasmania|1970|p=9}}
The completed Blair Street Bridge measures {{convert|650|ft|order=flip}} with six [[Span (engineering)|spans]], each {{convert|116|ft|order=flip}} long over the river.{{sfn|Department of Public Works Tasmania|1970|p=15}} It features [[reinforced concrete]] slabs for stability and [[steel girder]]s fabricated by Russell Allport & Co in [[Moonah, Tasmania|Moonah]]. The bridge design includes a 4.74% [[Grade (slope)|graded slope]], easing to a 3% vertical curve on Montagu Street,{{sfn|Department of Public Works Tasmania|1970|p=11}} ensuring resilience to heavy loads and adverse weather.<ref>{{Citation | author1=Wilson, D. R. | author2=Ratcliffe, S. | author3=Krohn, Simon. | author4=[[Hydro Tasmania]], issuing body. | author5=[[Department of Natural Resources & Environment|Department of Primary Industry, Fisheries & Energy]], issuing body| author6=Rivers and Water Supply Commission, issuing body. | title=New Norfolk flood plain study | year=1992 | section=3 online resources (74 unnumbered pages, 2 maps) : graphs, maps, tables. | series=Report (Tasmania. Hydro-Electric Commission. Water Resources Department) | location=Hobart, Tasmania | publisher=Hydro Electric Commission, Tasmania | url=http://nla.gov.au/nla.obj-2356617050 | id=nla.obj-2356617050 | access-date=6 March 2024 | via=Trove}}</ref>
==Significance== Upon its completion, the Blair Street Bridge represented a significant advancement in the town's infrastructure, offering improved safety, efficiency, and convenience for residents and visitors. The Blair Street Bridge eliminated the constraints imposed by the old structure, providing unrestricted access for vehicles and pedestrians while enhancing connectivity between the town's two main centres of development.{{fact|date=March 2024}}
==Notes== {{reflist|group=note}}
==References== {{Reflist}}
==Sources== *{{Citation | title=New bridge over the Derwent River at New Norfolk | publication-date=1970 | publisher=Department of Public Works Tasmania | url=https://trove.nla.gov.au/work/12135172 | access-date=29 December 2023 |ref={{sfnref|Department of Public Works Tasmania|1970}}}}
{{Crossings navbox |structure = Bridges |place = [[River Derwent, Tasmania|River Derwent]] |bridge = Blair Street Bridge |bridge signs = {{AUshield|TAS|A10}} |upstream = River Derwent Railway Bridge |upstream signs = [[Derwent Valley Railway (Tasmania)|Derwent Valley Railway]] |downstream = [[Bridgewater Bridge]] |downstream signs = {{AUshield|N|1}}<br>[[Midland Highway, Tasmania|Midland Highway]]}}
{{Road infrastructure in Hobart|state=collapsed}} {{Authority control}}
[[Category:Bridges completed in 1974]] [[Category:Concrete bridges in Australia]] [[Category:River Derwent (Tasmania)]] [[Category:Road bridges in Tasmania]] [[Category:1974 establishments in Australia]]