Keith Downey Dip CE, Dip Theol, FIE Aust
John Connal Dip CE, BE, MEngSci,MIE Aust
Keith Downey has spent 30 years engaged in the design and
construction of a wide range of civil engineering projects in
Victoria, Tasmania and Papua New Guinea. For the past 15 years he
has worked for the National Capital Development Commission
in various positions involved with the planning and design of
major engineering facilities in the ACT. He was the
Commission’s Design Manager for the Parliament House access roads
project. He is now Director of Capital Works and Services with
the National Capital Planning Authority.
John Connal is a graduate of Melbourne University and has spent
16 years in the design of civil engineering works; the past six of
these having been in Canberra. He is an Associate of the
consulting engineers, Maunsell and Partners, for which he has been
involved on major development projects in Canberra, having
moved to the National Capital originally to work on the Parliament
House access roads project.
THE design and construction of the roads and bridges to
the new Parliament House provided a rare opportunity
where the blended skills of a wide range of professions was
needed, to produce an integral, harmonious and appealing
The success of the blending process is evident by the local
and national recognition the work received. It was awarded
Engineering Excellence awards, firstly for the bridge
elements and later for the project as a whole, from the
Canberra Division of the Institution of Engineers,
Australia, as well as awards from the Association of Consulting
Engineers Australia and from the Concrete Institute of
Clearly, in such a significant project the influence of key
people is visible in the finished product. Primarily, in this
instance, it is the touch of Aldo Giurgola, of the project
Architects for the new House, Mitchell/Giurgola and
Thorp (MGT). As far as the roads and bridges are
concerned, the other major influences came from the late
Richard Gray, formerly of Holford & Partners (United
Kingdom), who was design adviser for the project to the
then National Capital Development Commission
(NCDC) as well as from architectural staff of the Commission.
The NCDC was the client for this work as it was responsible
for all works associated with the House outside
the 320 metre radius of the actual Capital Hill site.
EVOLUTION OF THE CONCEPT
The job of providing access to the new Parliament House,
whatever the design of the House, was always going to be
challenging. The Hill was at a node in Canberra’s transport
system, with the surrounding roads serving both a wider
metropolitan function as well as local access needs. The
rotary interchange system of State and Capital Circles
accommodated the peak traffic flows between
Commonwealth and Adelaide Avenues, with more than 43,000
vehicles using the route daily in 1980.
MGT’s winning design added yet a further dimension to
The access solution not only had to contend with the
strengths and weaknesses of the existing transport system,
plus provide for the future traffic demand for that part of
the transport network, but also had to provide safe and
convenient access to the new House.
Fig. 14.1: The access roads converge on the northern entry to
Parliament House (view from the top of the flagmast).Source: NCDC.
With up to 3,000 people working in the House, plus
official visitors (including Heads of State) and more than
one million tourists annually, the roads to the House had to
cater for a diversity of visitors and modes of transport:
private vehicles, buses, service delivery vehicles, vehicles in
ceremonial processions, people on foot and on bicycles.
The original competition design brief for the new House
contained possible access options including the radial
avenues and the symbolic access from the Land Axis (the House
is at the southern end of Griffin’s land axis from Mt Ainslie,
the Australian War Memorial and Anzac Parade). MGT’s
design chose to provide functional access from the
Adelaide, Commonwealth and Kings Avenues, with service
access from Brisbane Avenue. Ceremonial access was directly
up the Land Axis. This meant, of course, that with no
access from either Capital or State Circles a visitor would
have to choose a route to the House some distance from the
There were concerns that this lack of clarity would be
unacceptable. An early task for Maunsell & Partners, who
had been selected by NCDC in 1980, as Civil Engineering
Consultants for the roads and bridges, was to provide a
feasibility study for the proposed road design. The major
elements of the MGT design which had to be considered in
the study were:
a large entrance forecourt on the northern side of the
an internal, circulatory access system (now known as
two new roads extending from the medians of Commonwealth
and Kings Avenues
a road link from the median of Adelaide Avenue.
These aspects of the design raised some fundamental
issues. Problems of level differences, continuity of the Land
Axis and traffic safety all required sensitive consideration to
meet the new requirements of the design, along with the
existing demands of the traffic system.
Some innovative, and even some outlandish solutions
were contemplated, such as:
lowering the House to reduce the approach grades to it
filling in State Circle to provide at-grade entrance to
Capital Hill from the Land Axis
physically shifting the existing bridges which took
Commonwealth Avenue over State Circle, to provide
structures at the rear of the House
rearranging roads within the Parliamentary Triangle to
improve the central access to the site, at the expense of
restricting access from the Avenues.
While an over-riding factor was always that of budget, it
is hardly surprising that the impact of some of these
proposals stirred lengthy debate among the various disciplines
Probably the most difficult compromise to reach
involved the question of levels. The topography of the site
and all the requirements of the House design were
incompatible with simple and unobtrusive connections from the
two main access roads — Commonwealth Avenue and
The construction of a link to the new House, along an
extension of the Commonwealth Avenue median, with a
maximum grade of 8 per cent to Parliament Drive from a
point south of State Circle, dictated a maximum achievable
level of RL583m at Parliament Drive. Maintaining
symmetry across the Forecourt of the House, as was implicit
in the design for the House, meant that the Kings Avenue
extension would have to be at the same level. That would
require Kings Avenue being lowered by 3 metres at its
intersection with State Circle. This option was clearly
unacceptable, as it would require a gross distortion of the
Capital Circle profile to meet clearance requirements, and
would also require major earthworks, with significant
reconstruction costs, on State Circle.
Fig. 14.2: Parliament House Competition Document access opportunities.
Fig. 14.3: Access proposal embodied in the winning MGT
The solution adopted has an 8 percent grade from north
of the existing bridges over State Circle which has the effect
of vertically separating the extension above the level of the
existing structures. While this created a number of
complexities and the need for a new bridge in the median of
Commonwealth Avenue over State Circle, it allowed the
development of the appropriate elevation and entry
arrangement onto Capital Hill.
Maunsell & Partners’ feasibility study showed quite
clearly that MGT’s original proposal to provide a southern
link from Adelaide Avenue would be unworkable because
a. the anticipated amount of through-traffic on Parliament
Drive, caused by the relatively direct nature of the link
between Adelaide Avenue and Commonwealth Avenue
b. the location of the median offtake on a crest and the need
for traffic to cross an express bus lane.
Studies indicated two-way traffic volumes on Parliament
Drive would exceed 1,000 vehicles per hour even when the
average speed was reduced to 25 km/h, to reflect the likely
interference to through traffic of vehicles turning into car-
parks around Parliament House. This number of vehicles
was considered to be unacceptable for Parliament Drive.
This led to the alternative southern access being provided at
Melbourne Avenue via a bridge over Capital Circle which,
for clearance reasons, required Capital Circle to be lowered
about 1.5 metres.
The key to good accessibility to the House was Kings
Avenue. Here it was possible to provide an at-grade
intersection with State Circle, the prime distributor road to
Capital Hill. Direct access is made to Parliament House
from both directions on State Circle and from Kings
Avenue, the route being grade separated at Capital Circle,
with a bridge structure, and involving some regrading and
full signalisation of the Kings Avenue-State Circle
MGT’s original design proposed complex three-way
intersections at the junctions of the Avenue extensions with
Parliament Drive. When it became clear it would be extremely
difficult to provide for comfortable and safe traffic
flows, these were modified to simple T-junctions. They
allow better resolution of levels on the Forecourt and easier
access to the carpark underneath.
By early 1981 a compromise layout had been reached
(Figure 14.4). It embodied:
preservation of the integrity of the winning design
providing a safer, more convenient southern access at
satisfying the need for a high level of accessibility with
an at-grade intersection between State Circle and Kings Avenue
segregating the high speed inter-town traffic on Capital
Circle/Adelaide Avenue from the traffic accessing Capital Hill
maximising the future capacity of the total traffic
system to deal with general increases in urban traffic
preserving the geological feature in the State Circle
cutting, which had been retained as a significant feature in
earlier engineering works.
All this was achievable at an acceptable cost, estimated at
$30 million (1988 prices).
THE DESIGN PROCESS
The structures are the most dominant visual aspect of the
access solution. The major consideration during their
design was that they have all the necessary qualities of
functional road structures, as well as being compatible with their
The fundamental aesthetic quality desired of the bridges
was that they could be viewed as bridges in the landscape of
a country estate, inspired by the tradition of fine bridges
built in Australia in the 19th century and suggesting the
antithesis of high speed, highway structures. They all had
to have high aesthetic quality for both the upper roadway
and the lower roadway, being both major traffic routes and
used occasionally for ceremonial functions. Additionally,
they should have a “family” relationship to each other and
to the existing bridges in the area, through consistency of
basic shapes and details.
To achieve the “family” solution of bridges, many variables
had to be melded into a consistent theme. They
included variable road widths, different footpath widths,
different pier heights, consistency of new details and compatibility
of the new details with those of the existing
bridges in the precinct.
It was no easy task and required input from a range of
architectural consultants, from NCDC and from those
advising Maunsell & Partners and the Parliament House
Construction Authority (PHCA).
Fig. 14.4: The compromise solution.
From Griffin onwards the Central Area of Canberra has
been developed on the basis of strong landscape concepts.
Hence, the design concepts for both the new Parliament
House and the adjacent Parliamentary Triangle rely heavily
on major landscape elements for their integrity.
MGT’s design for the House relied heavily on using tree
planting to frame some views, while leaving others open.
Trees also would be important as windbreaks.
The Access Roads project, therefore, had to provide a
landscape solution that integrated the design concepts on
the Hill with those of the surrounding areas. The solution is
based on native species planted both formally and informally.
Considerable engineering works were required to establish
the ideal planting conditions, drainage and irrigation
The complexity of these issues, as well as judging future
growth of the trees resulted in the use of computer graphics
techniques to understand the interactions. The computer-
based work included generation of perspectives and
simulation of movement along the major vehicle routes. These
were varied to understand the situation in 1988, as well as
next century when the trees will have reached maturity.
Traffic During Construction
Capital and State Circles are focal points for the distribution
of central area traffic to the south. The free flowing Capital
Circle accommodated the major traffic movements
between Commonwealth and Adelaide Avenues, especially
during peak periods. Therefore, considerable emphasis had
to be placed on packaging and timing of works, so
construction could occur, as far as possible, under traffic.
Traffic-related considerations in phasing the work included:
the total period for construction was to be about four
years, from early 1983
the need to construct the work in packages, to suit
various financial and programming constraints
the advantages to be gained from closing sections of the
road network during construction of the bridge structures
the need to ensure that convenient alternative routes
were available when roads were closed.
There had to be access for up to 2,200 workers on the
Capital Hill construction site. Additionally, as the work
areas on the site changed, access locations had to be
modified to match, as near as possible, the changes.
Numerous options were considered in each stage, taking
account of the complex inter-relationships between the
separate contracts, the physical requirements of each stage
of the work and the changing access requirements. Sixty-
two traffic staging drawings were produced during this
task. The movement of traffic through the site was never
seriously impeded during the construction process.
The elements which comprised the total access solution to
the new House are many and varied. However, all these
elements were designed to be complementary, in both
principle and detail, to the architecture and landscape of the
House, while providing functional access to the House and
to integrate the House design into the surrounding precincts.
roadworks (including cycle paths and footpaths) at
Adelaide Avenue, the Adelaide Avenue-State Circle inter
change, Melbourne Avenue, Canberra Avenue, Kings
Avenue, Commonwealth Avenue, the Land Axis, State Circle,
Capital Circle and in the Parliamentary Triangle
bridges carrying Melbourne Avenue over Capital Circle
and Kings Avenue over Capital Circle and twin bridges on
the Land Axis over State Circle
a tunnel carrying Capital Circle under the Land Axis roads
a box section viaduct on the Commonwealth Avenue
extension, linking the new median bridge over State Circle
with the bridge onto Capital Hill
retaining walls associated with the bridges and tunnel
a pedestrian and cycle underpass on State Circle near Flynn Drive
bulk excavation of about 300,000 cubic metres on
Camp Hill and filling of the sector of the Land Bridge
between State and Capital Circles and the Avenue extensions
new drainage and service lines to the Parliament House
and diversions of existing services to facilitate construction
of the new roads, bridges and tunnel
drainage augmentation works, including construction
of two new retarding basins
soft and hard landscaping
protection of a geologically significant cutting on State
Circle and construction of a viewing platform on the Land
Both the architectural and engineering aspirations for
the structures were achieved by creating a construction
environment compatible with the production of high quality
work. Specification of the concrete work involved
consultation with concrete manufacturers and with the PHCA
and its other consultants. Prototypes were constructed for
all major elements of the work, with trials of different types
of surface finish to select a finish both economical and
appropriate for the location. Formwork stripping times for
all exposed concrete surfaces were carefully controlled to
ensure good colour control.
While there were exacting requirements for workmanship
, and access was difficult to much of the work, the
design and construction proved to be economical.
Construction techniques were generally conventional and
careful planning allowed completion of the structures ahead of
Fig. 14.5: Commonwealth Avenue extension from Capital Circle.
Commonwealth Avenue Extension
The highly prominent extension of Commonwealth
Avenue onto Capital Hill required the building of a new
bridge between the two existing bridges. The new median
bridge is raised above the levels of the existing bridges.
With three separate bridges merging in the middle of
Commonwealth Avenue from two different vertical and
horizontal alignments, the resolution of the converging
lines required considerable analysis and thought. Physical
models aided the design process, which was further complicated
by the fact that the ramps from and to Capital
Circle were at slightly differing levels. In the final design
the integration of precast parapet units and insitu concrete
faces, some with warping geometry, provided a solution
that provides a safe driving environment and has smooth,
clean lines which are pleasing to the eye.
The bridge over State Circle fills in between the existing
bridges, providing the effect of a continuous short tunnel
beneath the bridge. This tunnel effect was reduced by
recessing the soffit of the new deck above the level of the
existing deck soffits. The same bearing ribs as those on the
existing bridges are used on the new bridge and up-lighting
onto the soffit is used to enhance the lift of the new central
soffit area. This emphasises the emergence of the new
bridge and lightens the space below the structures.
Between the bridge over State Circle and the bridge onto
Capital Hill, is a box viaduct which sits on fill and is fully
supported along its length. The walls of the box section
provide the visual impression of a road extension, giving a
functional symmetry of approach to Capital Hill which
parallels that at Kings Avenue.
The project frequently called for innovative solutions.
Early in the design process, options for the abutments of the
new State Circle bridge were investigated. With the new
bridge higher than the existing structures, yet needing to
maintain the same foundation levels at the abutments, it
required large tall abutments. With a conventional design
approach, these abutments would have had massive footings
and wall sizes. Instead, the economical solution of
using approach spans was adopted. With this method the
space is spanned by approach spans of beam and slab construction.
In order to maintain the visual continuity of the
bridge structure, the approach spans were founded on the
rear faces of the cast insitu section of the bridge over State
The end bridge on the Commonwealth Avenue extension
is an asymmetrical structure. It has the appearance of
being firmly established in the landscape on the north side,
yet “leaping” across onto Capital Hill. The thin deck section
where the bridge passes onto the Hill was achieved by
counterweighting the bridge with a mass concrete weight
hidden behind the side walls of the abutment. This counter-
weight reduces the mid-span bending movements to
achieve the slender, asymmetrical structure. The support of
the bridge at the northern abutment uses a bearing rib
arrangement similar to the bridges over State Circle further
north on the Avenue extension.
Fig. 14.6: Bridge piers under the Land Axis, part of a common theme for all bridges.
The Land Axis
The Land Axis links the new Parliament House to the
Provisional House, with a formal approach of constant
grade. A design requirement was that the Land Axis provide
natural, uncomplicated vehicle access, plus a comfortable
pedestrian access. The formality of the approach is achieved
by providing a continuity of landscape between the two
buildings with irrigated grass and native tree planting
which emphasises the linear nature of the Land Axis.
The continuation of irrigated grass over State Circle is
achieved by the unusual solution of providing planter boxes
on the two bridges carrying the Land Axis roads over State
Circle. Grading of the deck surface, waterproofing, drainage
and soil were all chosen to encourage a quality grass
surface with no apparent difference between the grass in
this artificial planting environment and that on the adjacent
The bridges are shallow, prestressed girder structures
with a banana-shaped underbelly which was specifically
chosen to emphasise the slender nature of the bridges. They
have a bold and simple fascia created by a precast panel
which is angled to catch the light, and for frequent washing
The design of the bridges meets all NAASRA specified
loadings and includes stresses due to temperature differentials
through the depth of the deck. Additionally, as the
bridges were used to carry construction vehicles during the
excavation of Camp Hill, they were designed to support
loaded scrapers. The scrapers were restricted to the central
strip of the bridge to reduce asymmetrical loadings. A speed
restriction was also imposed on construction vehicles to
reduce load impacts.
The piers which support the deck comprise three columns
of varying height at each location and between the
bridges. Thoughtful design was required to ensure the
bridges did not create a forest of columns. After architectural
consultation, the result was a set of angular columns
with carefully chosen horizontal joints relating the
columns to each other. The angular cross section was
chosen to reduce the visual mass of columns. The columns
have been repeated on the Melbourne Avenue bridge in a
two-column pier arrangement.
Fig. 14.7: Diagrams of parapet options considered. The adopted
parapet is shown at the lower right.
Fig. 14.8: Bridge parapet termination details.
A great deal of attention was given to producing the most
appropriate design for the bridge balustrades and their
terminations. This was necessary because they would be
visually the strongest and most easily identifiable “family”
components of the bridges, both for users and as elements in
the landscape. A wide range of crashrail, handrail and
balustrade alternatives was considered.
Standard specifications require that all road overbridges
be designed to prevent vehicles from penetrating the edges
of the bridges and crashing onto the road below. On
conventional highway structures this is achieved by making the
bridge handrails strong enough to contain vehicles or by
incorporating a vehicular barrier adjacent to the kerb.
However, this project called for estate bridges (bridges in
the landscape), for which conventional techniques were
unsuitable. After much analysis of steel and concrete barrier
options, an edge parapet treatment was adopted for both
structural and aesthetic reasons. It consists of a solid
concrete balustrade surmounted by clean, crisp, precast fascia
units. The overall height of the concrete parapet is 1.1
metres and the outer faces are sloped outwards to enhance
the ability of the concrete to maintain a uniform colour as it
weathers and to minimise buildup of grime.
The strong, clean lines of the solid balustrades, in
conjunction with the bridge structures, achieve the desired
blending with the landscape and the House.
The termination of a bridge balustrade is as important as
the balustrade itself. The estate bridge theme suggested that
the parapets should have positive terminations in harmony
with the landscape. Various options were examined, and led
to the adoption of a detail commonly used on the stone-arch
bridges of the last century. The ends of the parapets gently
flare away from the roadway and terminate with concrete
A similar parapet was used on the tops of the Capital
Circle tunnel portals, to provide yet another link between
the structures leading to the new Parliament House.
Capital Circle Tunnel
Designing the Capital Circle Tunnel presented geometric
complexities. It was to be located on a reverse curve where
Capital Circle passed through an existing cutting. The
structure required greater width than the roadway pavement
in order to provide lateral sight distance clearance
around the curve.
This led to a barrel-vaulted shape solution, with the
footpaths at the springing lines of the arch allowing
adequate sight distance. The tunnel pavement rotates to
provide super-elevation from three per cent in one direction
to three per cent in the other direction. The rotation
was achieved by rotating the whole tunnel cross-section,
thus allowing a constant roof cross-section to be adopted for
ease of construction. The resulting geometry was complex
yet the easy-to-build section provides clean-flowing,
aesthetically pleasing lines.
The tunnel is 156 metres long between the large reinforced
concrete portals. The finish and joint pattern on
the portals was selected after lengthy consultation with the
Architects and with tunnel lighting designers. The portals
have a textured concrete finish in keeping with the rest of
the Parliament House complex, yet with an intensity of
colour which ensures economical lighting in the tunnel by
reducing the contrast between external and internal lighting
The barrel-vault design is effectively a tied arch with the
roadway slab forming the tension tie. Options of a pre-
stressed and reinforced concrete pavement were considered;
however, there was little cost differential and faster
construction was possible with a reinforced pavement. The
arch of the tunnel is connected to the portal walls via a ring
beam which offers stiffness to the portals and the arch, and
provides the architectural detail around the tunnel entry
The tunnel is constructed over two different rock strata.
At the three-quarter point of the tunnel, near the western
portal, a dipping fault line traverses the tunnel cross-
section, skewed to the longitudinal axis of the tunnel. On
either side of the fault the rock has different strength and
stiffness. East of the fault the rock allowable bearing pres-
sure is 270 kPa and stiffness (expressed as a modulus of
subgrade reaction) is 50 kPa/mm. West of the fault the
rock is the hard Black Mountain sandstone, which was
attributed as allowing bearing pressure of 400 kPa and a
stiffness of 5,000 to 25,000 kPa/mm.
The variation in rock stiffness presented problems for the
tunnel cross-section, with greater stresses being induced by
the differential settlement effects. Some thought was given
to articulating the tunnel at the fault to cater for the anticipated
differential movements. However, this would have
created problems with waterproofing the structure and
with the internal treatment of the articulation. Therefore, it
was decided to strengthen the tunnel cross-section at the
fault line, which simplified the solution and enabled the
interior of the tunnel to maintain a constant appearance.
The effect of the fault was firstly confined to a right angle
crossing by excavating soft rock and backfilling with mass
concrete to “square-up” the interface between soft and hard
foundations. The tunnel section straddling the fault was
then thickened and post-tensioned longitudinally. This
provided sufficient strength to resist the anticipated
differential settlement effects, which would be magnified by the
weight of the filling placed over the tunnel. During
construction the thickened section was initially isolated from
the standard sections to the east and west and later
connected, with a 2 metre closing pour, as the final stage in the
tunnel’s construction. The tunnel construction proceeded
from the eastern end to allow the casting on soft rock to
precede the casting on hard rock, which maximised the
amount of differential settlement that occurred prior to the
casting of the closing pours.
The effects of differential temperature and different
progressive levels of backfilling (the material coming from
Camp Hill) during construction were analysed in the
design. This led to the specification of a maximum
differential in backfilling heights of 2 metres from one side of the
tunnel to the other.
The flowing curvilinear lines of the tunnel are accentuated
by two lines of lighting, the intensity of which varies
through the tunnel. A high intensity of light is provided in
the entry portal, reducing along the tunnel as the driver’s
eyes adjust to the lower light levels.
The tunnel has automatic sprinklers, fire hydrants, hose
reels and warning devices linked to the ACT Fire Brigade
network. Axial flow fans, activated by carbon monoxide
monitors, operate should there be a buildup in carbon
monoxide in the tunnel.
Given the closeness of the tunnel to the new Parliament
House, a closed circuit television surveillance system allows
constant police monitoring of the tunnel.
All services within the tunnel are concealed within the
haunches at the arch springing lines, giving the tunnel a
clear flowing appearance which is emphasised by the strip
steel lining covering the curved arch. The lining has a
red-brick colour between the rows of lighting, and an
acoustic backing to minimise traffic noise.
Fig. 14.9: Capital Circle turned western portal.
Geologically Significant Rock Cutting
State Circle passes under the Land Axis in an existing cutting
through Camp Hill sandstone rock. The rock cutting
exposes a geologically significant rock profile which had to
be retained and protected from deterioration during the
The Land Axis roads are carried over State Circle on
bridges which have their northern abutments set back from
the face of the cutting and are founded at a level above a
berm which provides a top edge termination to the rock
The stability of this rock face was investigated and
drainage works were designed to prevent surface water flowing
over it and to minimise seepage and ground water pressure
behind the face. During construction care was taken to
protect the face from damage and the extent of remodelling
of the land contours during the removal of part of Camp
Hill was the subject of discussions with the Geological
Society of the ACT, to ensure that the rock face remained
A viewing platform has been constructed on the south
side of State Circle between the two Land Axis bridges, to
provide for formal viewing of the rock face.
Commencement Column Monument
On the original Capital Hill site a Commencement
Column Monument was officially laid, commemorating
the naming of Canberra as the Federal Capital.
The column comprised 63 stones with three foundation
stones, one each laid by the then Prime Minister, the Hon
Andrew Fisher; Sir Thomas Denman, Baron and Governor
General and Commander in Chief of the Commonwealth
of Australia; and the Hon King O’Malley, Minister of State
for Home Affairs at the time.
The naming ceremony took place on 12 March 1913, 75
years to the day prior to the monument’s relocation on the
Land Axis, and it was at the original ceremony that Lady
Denman named the Federal Capital Canberra.
The ceremony to officially relocate the monument from
its original site to its new site near the forecourt of the new
Parliament House was attended by the modern day counterparts
of the original participants, namely the Hon R.J.
Hawke, Sir Ninian Stephen and the Hon Gary Punch,M.P.
The relocation of the monument was one of the finishing
tasks in the access roads project, completed several months
prior to the opening of the new Parliament House.
Fig. 14.10: the clean lines of Capital Circle tunnel.
The construction of the roads and bridges to the new House
provided an opportunity to upgrade some adjoining areas,
to link them in with the complex. Areas upgraded included:
The Lodge retarding basin. The open area adjacent to The
Lodge was contoured, regrassed and planted with additional
trees. The shaping of the area formed a small retarding
basin to contain overland runoff.
Modifications to Adelaide Avenue bridge. Minor changes to
the Adelaide Avenue alignment required kerb and barrier rail modifications.
Scrivener’s Hut. The original hut used by Scrivener during
his survey for the National Capital site is located within
the annulus formed by State Circle. Landscaping works,
including a new cycle path, have upgraded this area, and the
hut is now adjacent to a public recreation area.
Construction of the works was carried out in five main
contracts, between 1983 and 1989, with all works substantially
completed for the official opening in May 1988.
The timing and size of the five packages of work were
adjusted to suit the traffic requirements of the site and cash
flow constraints. The main packages were, in chronological
Fig. 14.11: State Circle rock cutting prior to removal of Camp Hill,
showing abutments set back to preserve the integrity of the
Fig. 14.12: Ceremony markimg the repositioning of the Commencement Column monument on the Land Axix, 12 March 1988.
Southern Roadworks Package. These works concentrated
on roadworks required at the southern end of the site and
involved widening and lowering Capital Circle between
Canberra and Adelaide Avenues. Also constructed was the
Melbourne Avenue link towards Capital Hill and modifications
along Adelaide Avenue.
Bridges Package. This was principally a bridgeworks con-
tract with the construction of the two Land Axis bridges
over State Circle and the construction of the Melbourne
Commonwealth Avenue North Package. This contract
included all works on Commonwealth Avenue north of
Coronation Drive. It involved the reconstruction of the
Coronation Drive-Commonwealth Avenue intersection
and all the other minor road and drainage works in the
Commonwealth Avenue Extension Package. This was the
second largest package of work and involved construction
of the new central bridge and ramp structures up the centre
of Commonwealth Avenue, onto Capital Hill.
Tunnel Package. The Capital Circle tunnel was
constructed in this, the largest of the contracts. Under these
works, the Land Axis was formed, together with its
landscape. The Kings Avenue link was also established in this
package, with the construction of the Kings Avenue/State
Circle intersection and the building of a new bridge over
Capital Circle. This package of work substantially completed
the Parliament House access roads works.
The construction works involved some complex programming
and timing issues; however, the construction of
the works themselves involved no new or different
construction techniques. The quality of finish was achieved by
the application of good control over traditional construction
methods. All work was completed to schedule and the
initial estimates proved to be accurate, allowing for the
effects of inflation in the intervening years.
Fig. 14.13: Aerial view of construction in progress on tunnel, Land Axis bridges and Commonwealth Avenue extension.
This chapter draws heavily on the various reports and documents
produced by design agents, Maunsell & Partners, in the process of
design development and during their management of its construction.
The project was a major team effort with the authors part of that
team which comprised not only NCDC and PHCA staff but also
the many other consultants who worked on the project.
References and Sources
Parliament House Construction Authority. Parliament
House Canberra—Conditions for a Two-Stage Competition.
Volume One—April 1979.
Maunsell and Partners. Parliament House Access and
Roadworks, Pre-Design Report. Volume 1—Text, July
1981, Unpublished report to NCDC.
Maunsell and Partners. Parliament House Access and
Roadworks, Pre-Design Report. Volume 2—Illustrations,
July 1981, Unpublished report to NCDC.
Maunsell and Partners. Parliament House Access Roads,
Preliminary Design Report. January 1982, Unpublished report
Department of Main Roads, New South Wales. The
Aesthetics of Bridges. January 1987.