Locus: River Usk Crossing
[ As the train jerked its way out of Newport Station and over the river, I followed my usual habit of seeking out the view of the river, city, and monumental Transporter Bridge, a shifting frame of view as the train cut its way through...
... the habitual view was upset by the sudden glimpse of this massive, arching construction in the distance, as the train carved its own curve of velocity through the fleeting cityscape, a baffling new addition to the landscape... - JW]
steelconstruction.org
River Usk Crossing
Architect | Yee Associates
Structural Engineer | Faber Maunsell Ltd
Steelwork Contractor | Fairfield-Mabey Ltd
Main Contractor | Morgan-Vinci
Client | Newport City Council
The new Usk River Crossing is a landmark bowstring arch bridge forming the centrepiece of Newport's Southern Distributor Road (SDR).
The 9.5km SDR links M4 Junction 24 to Junction 28 and will provide relief to congested local roads and enhance cross river capacity. It is also intended to act as a key catalyst for local regeneration. Construction of the whole project has lasted two and a half years and at £55m it is the largest local Private Finance Initiative (PFI) scheme in Wales.
At concept stage a number of options were considered, with the arch finally being selected as most appropriate both symbolically and technically for its urban setting and historical context. A single clear span of 187m provided the best environmental solution, avoiding any permanent piers in the river. The arch form adds to the City's family of notable bridge types and ties in with the city's desire to develop a riverside walk linking the bridges. Newport's industrial heritage is reflected by the choice of steel for the bridge's construction; however, the design is distinctly modern.
Steel is the natural choice for a bridge of this span and type and is used for the primary elements of the superstructure - the arches, the hangers and all the deck beams. The bowstring arch is an efficient structural form that places minimum lateral loads on the foundations. Reinforced concrete is used to provide an economic deck slab, and this acts compositely with the steel beams.
The steel arch members are rectangular in cross section and are parabolic in elevation, tapering in depth towards their apex. They are inclined to convey a sense of enclosure and visual stability. The inclination gives the composition visual interest since the hangers will appear to crisscross when the bridge is viewed from an angle.
The bridge has been delivered by a unified team of designer, main contractor and steelwork contractor, with advice from the architect. This relationship has been a key to the success, and has enabled the design to be carefully tailored to suit not only the preferences of the steelwork contractor and erector, but also respond to the need for the contractor to maintain the bridge for the next 40 years.
Durability was therefore a key issue, which has been addressed in a number of ways. All steelwork above deck level was formed in box sections with no exposed ledges, to promote a clean design. The external surfaces of all the steelwork were treated with a high performance epoxy based paint system, with all box sections being fabricated from weathering steel and left unpainted internally. Weathering steel was utilised for the box members to avoid the significant safety issues associated with applying paint within a confined space, including eliminating the need for future maintenance painting. However, the small additional cost of the steel was more than offset by protective treatment savings.
The steelwork contractor created a fully detailed 3D computer model of the bridge, as input to his automated plate cutting and drilling machines. This model incorporated the significant computed deformations anticipated during erection.
The majority of the deck structure comprises a simple ladder-beam grillage formed from fabricated I sections, to make the most economical use of the steelwork contractor's automatic 'T & I' machine. For the arch, a careful examination of the economics demonstrated that the best solution lay in a rectangular section that was not stiffened longitudinally.
The river has dictated the approach used to erect the bridge. The size and weight of the structure was beyond the capacity of any available cranes to erect in one piece, and so a decision was taken to place two temporary piers in the river, at approximately third points of the span. The River Usk has the second largest tidal range in the world and work time in the river was significantly limited to suit ecological constraints to cater for migratory fish including salmon and the rare chad.
The erection of the superstructure followed a carefully developed sequence. The steel deck structure was assembled in two halves on either side of the river, utilising the pilecaps for the approaches as foundations for the temporary towers. Each half was then launched out over the river, crossing the temporary piers to meet in the middle. Temporary towers were erected on top of the temporary river piers, and a 1200 tonne capacity mobile crane lifted the outer arch sections such that they landed at the abutment and out onto the tower tops.
The central section of the arch was too heavy to lift directly into position, and so it was moved on skates to the centre of the bridge in sections and then welded together to form a single 680 tonne piece which was then raised to its final position using strand jacks. Once all welding was complete, the arch was lowered off the temporary towers to become free standing ready for installation of the hangers.
The initial stressing of the hangers lifted the deck off the temporary piers and was followed by the placing of the precast concrete deck panels. Using precast deck panels enabled most of the weight to be added such that the movements and deformations in the steelwork could take place in a controlled manner. In particular, the tie girder was expected to stretch by about 125mm, which if constrained by a partially constructed insitu concrete deck could produce uncertainty in load paths and cracking of the concrete. Final adjustment of the hangers was carried out before the stitches were concreted.
In conclusion, Newport has gained not only another much needed river crossing, but has gained an elegant steel structure in the process.
Judges' Comments:
The Usk crossing symbolises the best in British bridge engineering. It combines an elegant design, high quality fabrication and innovative construction. The box girder arches, with inclined parabolic form, are fabricated in weathering steel, externally painted and provide long-term maintenance benefits. Its elegance belies the 200 metres span.
Source here
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ Further
With the new river Usk crossing the construction team have created a landmark structure designed and built in an extremely compressed timescale- Once the DBFO contract was signed, “everyone was champing at the bit to get started”, says Faber Maunsell Technical Director Charles Cocksedge. There was no time for the traditional approach in which the engineer produces a completed design and passes it to the steelwork contractor: “We worked back from the completion date and found that Fairfi eld-Mabey would need to begin ordering steel less than two months from the start,” says Mr Cocksedge. “So we began by asking what can be designed first?”
steelconstruction.org
20 NSC July/August 2005
Structural Design Awards
River Usk Crossing
Newport’s 187m span bowstring arch bestrides the river as the
centrepiece of the £55M, 9.5km Usk Southern Distributor Road.
The outline design and the decision to go for a bowstring arch, in
which the road deck acts as a tie resisting the horizontal forces at
the arch springings, was by architect Ronald Yee of Yee Associates
for client Newport City Council.
“Newport already has a collection of notable bridges,” says Mr
Yee. This includes the 1906 Transporter Bridge and the 1964 George
Street Bridge, Britain’s fi rst large cable-stayed structure.
“We and the client were eager to create a family of bridges. We
looked at all the possible types and concluded that a bowstring
would be most appropriate, coupled with the fact that Newport did
not have a structure of this type already.”
The bowstring arch would create a landmark which would
become recognised as a symbol of Newport. Built of steel, it would
refl ect the area’s industrial heritage.
Main contractor Morgan-Vinci won the design, build, finance and
operate contract, with Faber Maunsell as designer. Fairfi eld-Mabey
was appointed steelwork contractor. These three worked extremely
closely together on the design.
Once the DBFO contract was signed, “everyone was champing
at the bit to get started”, says Faber Maunsell Technical Director
Charles Cocksedge. There was no time for the traditional approach
in which the engineer produces a completed design and passes it
to the steelwork contractor: “We worked back from the completion
date and found that Fairfi eld-Mabey would need to begin ordering
steel less than two months from the start,” says Mr Cocksedge. “So
we began by asking what can be designed first?”
Fairfi eld-Mabey chose to do the cross-girders of the ladder frame
deck: these span between the two tie girders, support the road and
are relatively self-contained as far as design is concerned.
These were followed by the tie girders and fi nally the arch itself.
The arch is formed from a fabricated box section, a good shape for
a compression member, a constant 2m wide and ranging from 2m
deep at the crown to 3m at the springing. The two tie beams are
2.5m deep I-sections, chosen because this is a more suitable section
for attaching the cross beams and is less expensive to produce, with
1200 x 60 mm fl anges and a 40mm thick web. The most complex
area to fabricate was the corner where the arch and tie beams meet
— at this point the tie girders widen out into a box section.
The design was critically affected by the construction sequence,
which also had to be considered. The arches were fabricated in 10m
lengths, and welded together on site with three sections each side.
The four end sections were lifted into place by the largest available
mobile crane in the UK, capable of lifting 1200t.
Even this did not have the capacity to lift the 75m centre section
of the arch into place. Instead this section was prefabricated, moved
along the deck on skates and then lifted into place using strand
jacks.
“The weight of the centre section was an important load case for
the design of the deck cross girders, which we were designing at a
stage when the weight of the arch was not precisely known,” says
Mr Cocksedge.
Construction of the deck was extremely rapid because Morgan-
Vinci prefabricated the deck sections in 3m x 5m concrete panels at
the site. The panels are supported on the fl anges of the tie girders
and cross girders, leaving room for insitu stitching strips to be cast
afterwards to tie the deck together.
From a design point of view this has the advantage that the tie
beams take all the tension, and are free to extend under the dead
load of the deck, by about125mm, both of which help to avoid the
risk of the concrete cracking.
With the deck stitched together, it acts compositely with both the
tie beams and cross girders to resist bending stresses due to traffi c.
Fairfi eld-Mabey Project Manager Julian Mason says: “This was
the largest box arch structure we’ve constructed for a while.”
Traditionally, he adds, at this sort of span a trussed arch rather than
a solid box used to be more common.
“The geometry was particularly complex because it’s a parabolic
arch which is also inclined,” he adds. Whereas in the past the
shape might have been approximated by fabricating it in a series
of straight lines, the Usk arch was modelled in 3D and cut using
automated machines to create a true parabola. As an additional
complication, dead-load precamber was added to cancel out the
calculated defl ection of the arch centre section under its own
weight.
The bridge opened at the end of last year after being completed
ahead of schedule. The judges’ verdict was: “The Usk crossing
symbolises the best in British bridge engineering. It combines an
elegant design, high quality fabrication and innovative construction.”
Source here (pdf)
corusconstruction.com
Structural steel design awards
37th structural steel design award winners
Thursday 23 June 2005
The 37th annual structural steel design awards have been presented to an unusually wide range of structures, from a private house in London to the huge tonnages involved in a steel works extension. Bridges featured strongly among the five Award winners, including a crossing of the River Usk and a small ‘rolling bridge’ on a residential development. Judges also gave commendations to three projects and a merit award to one.
(...)
The award winners were:
* The River Usk Crossing, Newport Southern Distributor Road
* The Wellcome Trust Gibbs Building
* Midland Mainline Rail Bridge
* Tower Environs Scheme
* Rolling Bridge, Paddington Basin
The River Usk Crossing, Newport Southern Distributor Road
Architect – Yee Associates
Structural Engineer – Faber Maunsell Ltd
Steelwork Contractor – Fairfield-Mabey Ltd
Main Contractor – Morgan Vinci
Client – Newport City Council
The Usk Crossing was said to symbolise “the best in British engineering”, combining elegant design, high quality fabrication and innovative construction.
Source here
corusconstruction.com
Corus has long been committed to supporting the continuous improvement of the construction industry. We manufacture and deliver a large range of high quality steel products from structural sections and plates through to cladding and light steel framing. Our long tradition of product development, technical support and educational programmes have helped the construction industry to make the most effective use of our steel products and has resulted in the UK being regarded as the world leader in steel construction.
Fact File
Name
River Usk Crossing, Newport Southern Distributor Road
Architect
Yee Associates
Structural Engineer
Faber Maunsell Ltd
Steelwork Contractor
Fairfield-Mabey Ltd
Main Contractor
Morgan-Vinci
Client
Newport City Council
Newport’s 187m span bowstring arch bestrides the river as the centrepiece of the £55M, 9.5km Usk Southern Distributor Road. It joins other notable bridges in Newport which include the 1906 Transporter Bridge and the 1964 George Street Bridge which was Britain first cable stayed structure
The bridge won a Structural Steel Design Award in 2005. The judges’ verdict was: “The Usk crossing symbolises the best in British bridge engineering. It combines an elegant design, high quality fabrication and innovative construction.” This result can only be attributed to the commitment of the unified team of designer, main contractor and steelwork fabricator working with advice from the architect to deliver this bridge. Corus as a world-class supplier to the best customers supported this commitment.
Source here
[Note: having stumbled upon this report on the new Newport bridge, The River Usk Crossing - whilst doing an image search for River Usk, in the hope of finding Alfred Russel Wallace's drawing of the River Usk, adjacent to his house- it seemed appropriate to start a blog on the theme of place. After the usual trial and error to select a blog name, locusplace was accepted.- JW]
... the habitual view was upset by the sudden glimpse of this massive, arching construction in the distance, as the train carved its own curve of velocity through the fleeting cityscape, a baffling new addition to the landscape... - JW]
steelconstruction.org
River Usk Crossing
Architect | Yee Associates
Structural Engineer | Faber Maunsell Ltd
Steelwork Contractor | Fairfield-Mabey Ltd
Main Contractor | Morgan-Vinci
Client | Newport City Council
The new Usk River Crossing is a landmark bowstring arch bridge forming the centrepiece of Newport's Southern Distributor Road (SDR).
The 9.5km SDR links M4 Junction 24 to Junction 28 and will provide relief to congested local roads and enhance cross river capacity. It is also intended to act as a key catalyst for local regeneration. Construction of the whole project has lasted two and a half years and at £55m it is the largest local Private Finance Initiative (PFI) scheme in Wales.
At concept stage a number of options were considered, with the arch finally being selected as most appropriate both symbolically and technically for its urban setting and historical context. A single clear span of 187m provided the best environmental solution, avoiding any permanent piers in the river. The arch form adds to the City's family of notable bridge types and ties in with the city's desire to develop a riverside walk linking the bridges. Newport's industrial heritage is reflected by the choice of steel for the bridge's construction; however, the design is distinctly modern.
Steel is the natural choice for a bridge of this span and type and is used for the primary elements of the superstructure - the arches, the hangers and all the deck beams. The bowstring arch is an efficient structural form that places minimum lateral loads on the foundations. Reinforced concrete is used to provide an economic deck slab, and this acts compositely with the steel beams.
The steel arch members are rectangular in cross section and are parabolic in elevation, tapering in depth towards their apex. They are inclined to convey a sense of enclosure and visual stability. The inclination gives the composition visual interest since the hangers will appear to crisscross when the bridge is viewed from an angle.
The bridge has been delivered by a unified team of designer, main contractor and steelwork contractor, with advice from the architect. This relationship has been a key to the success, and has enabled the design to be carefully tailored to suit not only the preferences of the steelwork contractor and erector, but also respond to the need for the contractor to maintain the bridge for the next 40 years.
Durability was therefore a key issue, which has been addressed in a number of ways. All steelwork above deck level was formed in box sections with no exposed ledges, to promote a clean design. The external surfaces of all the steelwork were treated with a high performance epoxy based paint system, with all box sections being fabricated from weathering steel and left unpainted internally. Weathering steel was utilised for the box members to avoid the significant safety issues associated with applying paint within a confined space, including eliminating the need for future maintenance painting. However, the small additional cost of the steel was more than offset by protective treatment savings.
The steelwork contractor created a fully detailed 3D computer model of the bridge, as input to his automated plate cutting and drilling machines. This model incorporated the significant computed deformations anticipated during erection.
The majority of the deck structure comprises a simple ladder-beam grillage formed from fabricated I sections, to make the most economical use of the steelwork contractor's automatic 'T & I' machine. For the arch, a careful examination of the economics demonstrated that the best solution lay in a rectangular section that was not stiffened longitudinally.
The river has dictated the approach used to erect the bridge. The size and weight of the structure was beyond the capacity of any available cranes to erect in one piece, and so a decision was taken to place two temporary piers in the river, at approximately third points of the span. The River Usk has the second largest tidal range in the world and work time in the river was significantly limited to suit ecological constraints to cater for migratory fish including salmon and the rare chad.
The erection of the superstructure followed a carefully developed sequence. The steel deck structure was assembled in two halves on either side of the river, utilising the pilecaps for the approaches as foundations for the temporary towers. Each half was then launched out over the river, crossing the temporary piers to meet in the middle. Temporary towers were erected on top of the temporary river piers, and a 1200 tonne capacity mobile crane lifted the outer arch sections such that they landed at the abutment and out onto the tower tops.
The central section of the arch was too heavy to lift directly into position, and so it was moved on skates to the centre of the bridge in sections and then welded together to form a single 680 tonne piece which was then raised to its final position using strand jacks. Once all welding was complete, the arch was lowered off the temporary towers to become free standing ready for installation of the hangers.
The initial stressing of the hangers lifted the deck off the temporary piers and was followed by the placing of the precast concrete deck panels. Using precast deck panels enabled most of the weight to be added such that the movements and deformations in the steelwork could take place in a controlled manner. In particular, the tie girder was expected to stretch by about 125mm, which if constrained by a partially constructed insitu concrete deck could produce uncertainty in load paths and cracking of the concrete. Final adjustment of the hangers was carried out before the stitches were concreted.
In conclusion, Newport has gained not only another much needed river crossing, but has gained an elegant steel structure in the process.
Judges' Comments:
The Usk crossing symbolises the best in British bridge engineering. It combines an elegant design, high quality fabrication and innovative construction. The box girder arches, with inclined parabolic form, are fabricated in weathering steel, externally painted and provide long-term maintenance benefits. Its elegance belies the 200 metres span.
Source here
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ Further
With the new river Usk crossing the construction team have created a landmark structure designed and built in an extremely compressed timescale- Once the DBFO contract was signed, “everyone was champing at the bit to get started”, says Faber Maunsell Technical Director Charles Cocksedge. There was no time for the traditional approach in which the engineer produces a completed design and passes it to the steelwork contractor: “We worked back from the completion date and found that Fairfi eld-Mabey would need to begin ordering steel less than two months from the start,” says Mr Cocksedge. “So we began by asking what can be designed first?”steelconstruction.org
20 NSC July/August 2005
Structural Design Awards
River Usk Crossing
Newport’s 187m span bowstring arch bestrides the river as the
centrepiece of the £55M, 9.5km Usk Southern Distributor Road.
The outline design and the decision to go for a bowstring arch, in
which the road deck acts as a tie resisting the horizontal forces at
the arch springings, was by architect Ronald Yee of Yee Associates
for client Newport City Council.
“Newport already has a collection of notable bridges,” says Mr
Yee. This includes the 1906 Transporter Bridge and the 1964 George
Street Bridge, Britain’s fi rst large cable-stayed structure.
“We and the client were eager to create a family of bridges. We
looked at all the possible types and concluded that a bowstring
would be most appropriate, coupled with the fact that Newport did
not have a structure of this type already.”
The bowstring arch would create a landmark which would
become recognised as a symbol of Newport. Built of steel, it would
refl ect the area’s industrial heritage.
Main contractor Morgan-Vinci won the design, build, finance and
operate contract, with Faber Maunsell as designer. Fairfi eld-Mabey
was appointed steelwork contractor. These three worked extremely
closely together on the design.
Once the DBFO contract was signed, “everyone was champing
at the bit to get started”, says Faber Maunsell Technical Director
Charles Cocksedge. There was no time for the traditional approach
in which the engineer produces a completed design and passes it
to the steelwork contractor: “We worked back from the completion
date and found that Fairfi eld-Mabey would need to begin ordering
steel less than two months from the start,” says Mr Cocksedge. “So
we began by asking what can be designed first?”
Fairfi eld-Mabey chose to do the cross-girders of the ladder frame
deck: these span between the two tie girders, support the road and
are relatively self-contained as far as design is concerned.
These were followed by the tie girders and fi nally the arch itself.
The arch is formed from a fabricated box section, a good shape for
a compression member, a constant 2m wide and ranging from 2m
deep at the crown to 3m at the springing. The two tie beams are
2.5m deep I-sections, chosen because this is a more suitable section
for attaching the cross beams and is less expensive to produce, with
1200 x 60 mm fl anges and a 40mm thick web. The most complex
area to fabricate was the corner where the arch and tie beams meet
— at this point the tie girders widen out into a box section.
The design was critically affected by the construction sequence,
which also had to be considered. The arches were fabricated in 10m
lengths, and welded together on site with three sections each side.
The four end sections were lifted into place by the largest available
mobile crane in the UK, capable of lifting 1200t.
Even this did not have the capacity to lift the 75m centre section
of the arch into place. Instead this section was prefabricated, moved
along the deck on skates and then lifted into place using strand
jacks.
“The weight of the centre section was an important load case for
the design of the deck cross girders, which we were designing at a
stage when the weight of the arch was not precisely known,” says
Mr Cocksedge.
Construction of the deck was extremely rapid because Morgan-
Vinci prefabricated the deck sections in 3m x 5m concrete panels at
the site. The panels are supported on the fl anges of the tie girders
and cross girders, leaving room for insitu stitching strips to be cast
afterwards to tie the deck together.
From a design point of view this has the advantage that the tie
beams take all the tension, and are free to extend under the dead
load of the deck, by about125mm, both of which help to avoid the
risk of the concrete cracking.
With the deck stitched together, it acts compositely with both the
tie beams and cross girders to resist bending stresses due to traffi c.
Fairfi eld-Mabey Project Manager Julian Mason says: “This was
the largest box arch structure we’ve constructed for a while.”
Traditionally, he adds, at this sort of span a trussed arch rather than
a solid box used to be more common.
“The geometry was particularly complex because it’s a parabolic
arch which is also inclined,” he adds. Whereas in the past the
shape might have been approximated by fabricating it in a series
of straight lines, the Usk arch was modelled in 3D and cut using
automated machines to create a true parabola. As an additional
complication, dead-load precamber was added to cancel out the
calculated defl ection of the arch centre section under its own
weight.
The bridge opened at the end of last year after being completed
ahead of schedule. The judges’ verdict was: “The Usk crossing
symbolises the best in British bridge engineering. It combines an
elegant design, high quality fabrication and innovative construction.”
Source here (pdf)
corusconstruction.com
Structural steel design awards
37th structural steel design award winners
Thursday 23 June 2005
The 37th annual structural steel design awards have been presented to an unusually wide range of structures, from a private house in London to the huge tonnages involved in a steel works extension. Bridges featured strongly among the five Award winners, including a crossing of the River Usk and a small ‘rolling bridge’ on a residential development. Judges also gave commendations to three projects and a merit award to one.
(...)
The award winners were:
* The River Usk Crossing, Newport Southern Distributor Road
* The Wellcome Trust Gibbs Building
* Midland Mainline Rail Bridge
* Tower Environs Scheme
* Rolling Bridge, Paddington Basin
The River Usk Crossing, Newport Southern Distributor Road
Architect – Yee Associates
Structural Engineer – Faber Maunsell Ltd
Steelwork Contractor – Fairfield-Mabey Ltd
Main Contractor – Morgan Vinci
Client – Newport City Council
The Usk Crossing was said to symbolise “the best in British engineering”, combining elegant design, high quality fabrication and innovative construction.
Source here
corusconstruction.com
Corus has long been committed to supporting the continuous improvement of the construction industry. We manufacture and deliver a large range of high quality steel products from structural sections and plates through to cladding and light steel framing. Our long tradition of product development, technical support and educational programmes have helped the construction industry to make the most effective use of our steel products and has resulted in the UK being regarded as the world leader in steel construction.
Fact File
Name
River Usk Crossing, Newport Southern Distributor Road
Architect
Yee Associates
Structural Engineer
Faber Maunsell Ltd
Steelwork Contractor
Fairfield-Mabey Ltd
Main Contractor
Morgan-Vinci
Client
Newport City Council
Newport’s 187m span bowstring arch bestrides the river as the centrepiece of the £55M, 9.5km Usk Southern Distributor Road. It joins other notable bridges in Newport which include the 1906 Transporter Bridge and the 1964 George Street Bridge which was Britain first cable stayed structure
The bridge won a Structural Steel Design Award in 2005. The judges’ verdict was: “The Usk crossing symbolises the best in British bridge engineering. It combines an elegant design, high quality fabrication and innovative construction.” This result can only be attributed to the commitment of the unified team of designer, main contractor and steelwork fabricator working with advice from the architect to deliver this bridge. Corus as a world-class supplier to the best customers supported this commitment.
Source here
[Note: having stumbled upon this report on the new Newport bridge, The River Usk Crossing - whilst doing an image search for River Usk, in the hope of finding Alfred Russel Wallace's drawing of the River Usk, adjacent to his house- it seemed appropriate to start a blog on the theme of place. After the usual trial and error to select a blog name, locusplace was accepted.- JW]
posted by J. at 12:50 PM
0 Comments:
Post a Comment
<< Home