Allan Truss Bridges

The third type of timber truss bridges are the Allan truss bridges. Percy Allan joined Public Works Department of NSW and in 1890, he designed a completely new truss based on the American Howe truss. It had many improvements over the McDonald truss, could carry heavier loads and used less timber. The main advantage was the use of many smaller pieces of timber spliced together for the top and bottom chords. This did away with the huge single beam of earlier truss designs. Also, the top and bottom chords had the timber beams arranged in pairs with a gap between them. This allowed the iron rods to be placed in the gaps instead of drilling holes in the timber. The gaps also helped prevent water collecting and rotting the timbers. Another significant advantage was that any piece of timber could be replaced without taking the bridge out of service.
Allan truss bridges were built from 1894 to 1929 and 105 were constructed in this period.

Statistics
Number built:    105
Number remaining:    20 (16 under state government, 4 under local council)
Number to be preserved:    16

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This bridge is located on Abercrombie Road about 55km south of Blayney and 112km north of Goulburn. It is a three span bridge over the Abercrombie River. It is built in 1919 on the masonry piers of a former Old PWD bridge. It is unique in that it has two different truss span sizes. The centre span is a 90 foot span while the outer two are 70 foot spans. The bridge has been rebuilt and strengthened and unfortunately, painted white. It would be nice if some of the timber truss bridges were left in the old colours - brown in this bridge's case.

View of the bridge from a convenient hill.

View of the bridge showing the different truss heights and the steel railing.

View of the bridge showing the stressed laminated deck and the maintenance gantry.

Closer view of the centre truss.

View of the bridge from the nearby hill.

Closer view of the bridge.

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Barrington Bridge is located just to the north of the small town of the same name and crosses the Barrington River. The bridge is a two span bridge built in 1920. It has not been rebuilt and is not going to be preserved. It is noticeably narrower than most timber truss bridges. Update April 2021: This bridge has been replaced with a new bridge with the old bridge currently still intact. Update May 2022: The old bridge has been demolished.

View of the bridge from.

View from the north side showing how narrow this bridge is.

Side view of the north truss.

Closer view of the truss.

The rounded posts at the end of the railing is a feature on nearly every timber bridge in NSW.

View showing the uneven lengths of the cross beams. On rebuilt bridges these are all exactly the same length.

View from the north side.

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Beryl Bridge is a small two span bridge crossing Wyaldra Creek about 8km west of Gulgong on Beryl Road. It uses the smaller 70 foot trusses. It has recently had substantial maintenance carried out, but has not been upgraded or rebuilt. The bridge was built in 1927.

View of the whole bridge.

View of the bridge from the west side.

View of the underside.

View of the bridge from the east side.

View showing the cross beams.

View of the bridge from the creek bed.

View of the bridge deck.

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This bridge is a two span Allan truss with a bascule lift span. It is one of only two remaining bridges with this type of lift span and the only one left with timber trusses. The bridge was built in 1922 and crosses the Murumbidgee River. The lift span has not been operated since the 1930s and cannot lift now as the deck has been laid continuously over the joins. As of mid 2014, the bridge is undergoing restoration. This will not include making the lift span operational again. The truss spans have been restored and work is underway on the ironwork of the lift span. New steel railings have been installed on the lift span and southern approach. Update February 2021: This bridge has been bypassed with a new bridge constructed just to the west of the old bridge. The old bridge is going to be preserved, but unsure if it will be accessible for road traffic or just pedestrians.

View of the bridge.

View of the deck and lift span tower..

View of the two truss spans.

View of the lift structure.

View of the trusses.

Detail of the lift mechanism. It was operated by hand and the weights rolled down the slopes as the lift span was raised.

View of the lift span.

Information plaque.

View of the bridge sign.

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This bridge is a single span bridge built in 1901 over the Mongarlowe River. It is located on Nerriga Road about 30km north of Braidwood. The bridge has had its piers reinforced with steel. The truss span, however, is pretty much original. This bridge is not going to be preserved. Update Febraury 2021: This bridge has been bypassed with a new bridge constructed to the south of the old bridge. The old bridge has not yet been demolished and there are calls to preserve it. Update May 2022: The old bridge has been demolished.

View of the bridge.

Side on view of the bridge. This view shows the steel pier reinforcements.

View of the bridge trusses and deck.

Charleyong Bridge is in a quiet, peaceful location.

View of the approaches with reinforced piers..

View of the bridge.

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Dunmore Bridge was built in 1899 over the Paterson River. It is a three span overhead braced truss with a lift span. The lift span has not operated since the 1940s. The bridge has recently been fully rebuilt. This involved building completely new trusses. The old trusses were lifted out and the new ones in by a 300 ton crane. The only thing that I think could improve it would be to use timber railing rather than the steel railing used for truss bridge rebuilds. This bridge is difficult to photograph as there is no access to get side views and there is a lot of traffic.

Distant side view of the bridge.

View from the south end.

View of the bridge trusses and deck.

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This bridge is a single span truss over the Molonglo River. It is located on Hoskinstown Road just off Captains Flat Road about 12km north of Captains Flat. Built in 1896, it is still pretty much original. It has a 5 ton load limit and a 3 metre height limit. Unlike nearly every other timber truss bridge, it has a single layer of deck planking.

General view of the bridge.

Side view of the bridge and Molonglo River..

I'm not sure why the row of white posts was there.

Close angle view of the bridge.

Underside of the bridge showing the single layer of deck planking.

End view of the bridge.

View of the deck..

Detail of the bottom chord and diagonal member mounting points.

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Gundaroo Bridge is a single span truss built in 1920 over the Yass River. The bridge was replaced in 2009 and the old bridge was demolished in March 2014. These photos were taken in February 2014. The bridge was located on Sutton Road just south of the community of Gundaroo.

General view of the bridge.

End view of the bridge.

View from the north side.

Close angle view of the bridge.

View of the whole bridge.

View of the bottom chord in very poor condition.

View of the top chord.

The new and the old.

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Hampden Bridge was built in 1895 over the Murumbidgee River in Wagga Wagga and was the first overhead braced Allan truss. It was a three span bridge with a long approach on the northern side. The bridge remained in use till 1985, when a new bridge was opened a short distance downstream. The original bridge was retained as a pedestrian bridge until 2006, when one of the trusses sagged alarmingly. The span was supported with a temporary steel truss. Hampden Bridge was demolished in July 2014 after the Wagga Wagga council decided it would be too expensive to restore the bridge.

View of the bridge from the south side. The bottom chord of the first truss can be seen sagging in this view.

View of the bridge and Murumbidgee River.

Mirror shot.

View of the trusses.

View of the bridge from the south end showing the support truss and the date stone on the left.

View from the south side.

View from the approaches on the north side.

View from the north bank of the river.

The approach spans.

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This bridge crosses the Paterson River near the community of Hinton and was built in 1901. The lift span has not been used since the 1940s. Hinton Bridge was been fully restored and upgraded. This was the first of the bridges to receive the "modernizing" treatment. This includes replacing the cross girders with steel, installing steel plating on the insides of the bottom chord timbers, replacing the deck with stress laminated timber and replacing the railing with steel railing. The result is a much stronger bridge that still looks like the original bridge.

View of the bridge from the south side.

Closer view of the bridge.

View of the underside showing the stress laminated deck. Aso just visible are the steel plates on the insides of the bottom chords.

View of the lift span.

Close up view of the south truss.

View of the deck from the north end.

View of the bridge from another angle.

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Mill Creek Bridge is a unique type of Allan truss. The standard from of the truss was modified to suit this particular crossing. The bridge crosses Mill Creek about 4km east of Wisemans Ferry on the road to Gosford. The main differences are the use of timber, rather than iron footings for the diagonals and steel, instead of timber for the cross beams. The cross beams are also mounted below the bottom chord, rather than above it. The bridge was built in 1929 and is currently out of use, a new bridge being constructed beside the old a few years ago.

View of the bridge from the side.

Information board.

View from the west end.

View of the steel cross beams and timber sway bars.

Close up view of the timber footings.

Timber end footing.

View of the bridge from the east side.

View of the bridge from the new road.

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This bridge was built in 1898 and crosses the Hunter River at the historic town of Morpeth. It is a three span overhead braced truss, one of only two remaining. This bridge will be preserved and has already been partially restored and upgraded. The approach spans have all been replaced with concrete spans.

View of the bridge from the north bank.

View of the new approach spans.

View of the trusses and approach spans.

View of the bridge from the south bank of the river.

Close up view of the centre span.

View of the truss spans and approaches.

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Paytens Bridge is located on Grenfell-Eugowra Road just off the Lachlan Valley Way, about 30km east of Forbes. It is a two span bridge and crosses the Lachlan River. It is mostly original with the exception of the steel central pier. This bridge is not going to be preserved and will be eventually replaced. It is difficult to get good side angle photos of this bridge.

View of the bridge from the south bank of the river.

View of the bridge from the south end.

View of the trusses.

Detail view of the end diagonal footing..

The central pier was replaced with this steel structure several years ago.

View of the truss.

View of the approaches with the original decking.

View of the bridge from the north end.

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This bridge is located on New Buildings Road, a few km south of Mount Darragh Road, about 30km west of Pambula. It is a single span truss and is in very poor condition. Pretty Point Bridge is a council maintained bridge and is not likely to be preserved. The bottom chord has been reinforced with steel in several places. It crosses Mataganah Creek.
Update August 2016: This bridge has been heavily modified. The trusses have been removed and the main span is now supported by large steel beams. The bridge will be eventually rebuilt and the timber trusses will be replaced. They will carry no load and be there for cosmetic and historic value only. This work is ongoing.

View of the bridge from the north end.

View of the bridge from the south side.

View of the trusses. This bridge has only four sway bars on each side, the usual number for unrestored bridges.

View from below. The steel reinforcement of the bottom chord is visible in this view.

View of the deck.

View from the south end.

View of the bottom chord.

View of the bottom chord.

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Rossi Bridge is a three span bridge built on the masonry piers of a former Old PWD bridge built in 1867 The current trusses were built in 1899. It crosses the Wollondilly River on Range Road just west of Goulburn. This road has a load limit of 15 tons. Because of this, the bridge does not need to be strengthened and will be preserved without upgrading with modern materials.

View of the bridge from the south side.

View of the bridge from the south end.

View of the trusses.

View from the other south side.

View of the deck.

View from the north end.

Side view of the truss.

View from the south end.

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This bridge was constructed in 1896 and crosses the Murray River at the town of Swan Hill. It is a two span bridge with a lift span. The bridge has had a lot of strengthening and upgrading work done, including on the lift span, which is still operational. This bridge was going to be preserved but is now going to be replaced with Toolybuc Bridge being retained instead. Planning is underway for the new bridge.

View of the bridge from the north side.

View of the bridge from the south end.

Close view of the bridge.

View showing the pedestrian walkway that is not original. If the bridge is preserved, this will probably be removed.

View of the deck.

View from the north side.

View of the bridge.

View of the underside of the approach spans..

View from the north end.

View from the south end. These bridges are quite a bottleneck for heavy trucks and are the a big reason why there are no big trucks in NSW.

View of the lift span.

View of the lift span.

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Tharwa Bridge crosses the Murumbidgee River about 35km south of Canberra at the community of Tharwa. It was constructed in 1895 and is the only remaining four span timber truss bridge. The original bridge was closed in 2006 due to severe deterioration of the timbers. A new bridge was almost built, but the ACT government then decided to restore the original bridge (the local community was also strongly opposed to the idea of a new bridge. The bridge was completely rebuilt and the concrete piers strengthened and the bridge was reopened in 2010.

View of the bridge from the east side.

View of the bridge from the east end.

View of the bridge deck and trusses.

View of the underside showing the maintenance gantry and stress laminated deck.

Closer view of the bridge. The steel reinforcements of the concrete piers are visible in this view.

Detail of the truss showing steel footings and splice plates.

There are a few pedestrian alcoves.

View of the original bridge from the west side in December 2005.

View from the west side in December 2005.

View from the west side of the original bridge in December 2005. Note the timber railing.

Close up of one of the trusses.

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Tooleybuc bridge was built in 1925 and crosses the Murray River at the tiny town of Tooleybuc. It is a two span bridge with lift span and is quite similar to Swan Hill Bridge, differing in having, shorter, low profile trusses. As of May 2014, it was undergoing maintenance with one truss supported by a Bailey truss. This bridge was not going to be preserved and planning was underway for a new high level bridge upstream of the existing bridge. It is now going to be upgraded and retained with the Swan Hill Bridge being replaced instead. Toolybuc Bridge has already had a lot of strengthening work done such as replacing the cross beams with steel and installing new sway bars. The lift span is still operational.

View of the bridge from the south side.

View of the bridge from the south end.

View of the bridge from the south river bank.

View of the lift span.

View of the truss showing the steel cross beams and new sway bars.

View from the north side.

View of the deck.

View from the north side with signage.

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Vacy Bridge is a two span truss built in 1898. It crosses the Paterson River about 20km north of Maitland on Gresford Road. In November 2013, it had Bailey trusses in place. This was due to another bridge nearby being partly closed for upgrade works. The Bailey trusses were installed on Vacy Bridge to cater for the increase in traffic. As of May 2014, Vacy Bridge is undergoing a complete reconstruction with new trusses being installed. This is unexpected as this bridge is not on the list to be preserved.

View of the bridge from the south side.

View of the bridge from the north side.

View of the bridge from the north end.

Another view from the north end.

View of the bridge in the countryside.

View showing the tall timber pier.

View of the truss in November 2013.

Same view in May 2014 with the new trusses going in.

View of the huge crane in use.

View from the north side. The old trusses have been removed, but the new ones are not yet in place on this side of the bridge

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This bridge is a three span truss built in 1897 crossing the Turon River on Hill End Road, 4km west of the historic town of Sofala, north of Bathurst. It has been fully restored and upgraded. It is not, however, on the list of bridges to be preserved, but it will be around for a while yet. It is located in a beautiful, peaceful setting.

View of the bridge from the north side.

View of the bridge from up a tree on the south side.

Detail of the truss showing the steel cross beams and new sway bars.

Underside view showing the iron piers and the dry riverbed as it was in February 2014.

Close angle of the bridge from the north side.

View showing bottom chords and the stress laminated deck..

View of the bridge from a distance in the dry river bed.

View of the deck and trusses.

View from the south end.

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Wee Jasper Bridge is located at the west side of the locality of Wee Jasper. It crosses the Goodradigbee River on Wee Jasper Road about 50km south west of Yass and was built in 1896. The river is on the edge of the Burrinjuck Reservoir. This bridge has been fully restored and will be preserved. It is in a very picturesque and peaceful setting at the end of a very curly road!

View of the bridge from the west side.

View of the bridge from the west end.

View from the east side.

View from the bank on the east side.

Detail of the truss. Unlike most other truss bridges, this one is painted black below the road deck.

View showing the cross beams and deck..

View of the deck and hill on the east side.

View of the whole bridge from the west side.

View from underneath.

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This three span bridge is located on Prince Street in Picton, about 80km south west of Sydney. It crosses a steep valley and has the tallest timber trestles in NSW. The bridge is limited to light traffic only and is going to be preserved without being upgraded. It has a pedestrian walkway within the trusses, unlike any other truss bridge. Due to the terrain, it is difficult to get side photos of this bridge. It also has a height limit of 2.4m, which prevented the Google Streeview car from crossing it.

View of the bridge from the east side.

View of the bridge showing the pedestrian walkway.

View of the tall trestles.

As best a side view as I could get.

View from the east end.

View from the west end showing the height limiter.

View of the truss.

View of the height limiter on the east end.

View of the deck.

Bridge Name	Date Built	# of Spans	Location	Waterway Name	Status	To be preserved?
Abercrombie	1919	3	South of Blayney	Abercrombie River	Rebuilt	Yes
Barrington	1920	2	Barrington	Barrington River	Demolished	No
Beryl	1927	2	West of Gulgong	Wyaldra Creek	Not rebuilt	Yes, for now
Carrathool	1922	2 + bascule	Carrathool	Murumbidgee River	Bypassed	Yes
Charleyong	1901	1	Nerriga Road	Mongarlowe River	Demolished	No
Dunmore	1899	3 + lift	Woodville	Paterson River	Rebuilt	Yes
Foxlow	1896	1	Hoskinstown Road	Molonglo River	Not rebuilt	Not sure - this is a council bridge
Gundaroo	1920	1	Gundaroo	Yass River	Demolished	Demolished March 2014
Hampden	1895	3	Wagga Wagga	Murumbidgee River	Demolished	Demolished July 2014
Hinton	1901	2 + lift	Hinton	Paterson River	Rebuilt	Yes
Mill Creek	1929	1	East of Wisemans Ferry	Mill Creek	Bypassed	Yes
Morpeth	1898	3	Morpeth	Hunter River	Partially rebuilt	Yes
Paytens	1926	2	Grenfell-Eugowra Road	Lachlan River	Not rebuilt	No
Pretty Point	?	1	New Buildings Road	Mataganah River	Demolished	Cosmetic only
Pyrmont	?	n/a	Sydney	Sydney Cove	Rebuilt	Yes
Rossi	1899	3	Goulburn	Wollondilly River	Original	Yes, without modern materials
Swan Hill	1896	2 + lift	Swan Hill	Murray River	Rebuilt	No
Tharwa	1895	4	Tharwa	Murumbidgee River	Rebuilt	Yes
Tooleybuc	1925	2 + lift	Tooleybuc	Murray River	Partially rebuilt	Yes
Vacy	1898	2	Vacy	Paterson River	Under rebuild	Yes, for now
Victoria	1879	3	Picton	unknown	Original	Yes, without modern materials
Wallaby Rocks	1897	3	West of Sofala	Turon River	Rebuilt	Yes, for now
Wee Jasper	1896	1	Wee Jasper	Goodradigbee River	Rebuilt	Yes