AESTHETIC EVALUATION OF CONCRETE STRUCTURES ON THE MACKAYS TO PEKA PEKA EXPRESSWAY

A W CHARLESON

School of Architecture, Victoria University of Wellington SUMMARY Eight criteria have been adopted from landscape architecture literature to evaluate the aesthetic qualities of the concrete structures on the new MacKays to Peka Peka Expressway. These criteria that are briefly defined and illustrated by examples of architectural concrete structures are then applied to evaluate the expressway structures comprising retaining walls, footbridges, under and overpasses and screening walls. Results of these evaluations indicate that observers of the expressway enjoy higher quality aesthetic experiences than the expressway users, and that the aesthetic qualities of two retaining walls and footbridges exceed those of the expressway bridges and screening walls. In general, the reviews of the structures from this landscape architectural perspective reveal a lack of novelty, variety, pleasure and sense of place. A series of questions is posed to assist designers incorporate these qualities more extensively into future structures. Overall, the aesthetic ratings of the structures were quite low. Yet a simple and limited international survey of motorway bridge structures indicates that the structures reviewed here can be considered to be of a satisfactory to high standard. The survey highlights the really difficult challenge for designers subject to many hidden constraints to achieve structures with high aesthetic qualities. In spite of these difficulties, the aesthetic qualities of two retaining walls and one footbridge on the MacKays to Peka Peka Expressway are considered to be outstanding. INTRODUCTION The need to reflect on the aesthetics of structures in the landscape was brought home to me in late 2016 when driving along State Highway 2 near Lower Hutt. I was struck by the blandness of a recently completed overpass. I just could not imagine how a more boring bridge could be designed, nor one that could be so oblivious to its landscape context. Rather than engaging in what would be harsh review of that bridge I take a far more constructive approach and review the concrete structures on the MacKays to Peka Peka Expressway that opened in late February 2017. Since all expressway structures are situated in a landscape this review is undertaken from a landscape architecture perspective. Therefore we do not consider a structure in isolation but view it in its landscape context. This is the approach taken by landscape architects who in their landscape interventions seek to not only meet the numerous pragmatic design criteria set by

their clients, but also, as much as possible, to provide users with aesthetically satisfying experiences. Michael Murphy (2005) categorizes aesthetic qualities that users expect in such experiences. These are slightly modified, listed and explained briefly below and form the basis of the reviews undertaken on the expressway structures. Although these qualities are relevant to all landscape designs, including structures situated in any landscape, they also apply to any human activity, such as preparing a meal or undertaking an architectural design. I illustrate each of these qualities with an example of architectural structure rather than landscape structure in order to be more inclusive for this keynote address. Murphy (2005a) also provides a long list of thirty potential design intentions or goals that can help evaluate the performance of a landscape design project. These goals actually encompass the aspects referred to previously, but also include many more related to the social and physical features of a design including obvious practical concerns like economy and resource utility. Two goals that are selected from this list, ‘Pleasure’ and ‘Sense of place’, are included in the total of eight qualities or criteria by which to evaluate structures in the landscape. They are discussed below. CRITERIA USED TO EVALUATE STRUCTURES IN THE LANDSCAPE As mentioned above, each criterion is listed below and briefly defined with an example of an architectural structure. Note that some of these example structures could equally illustrate one or more other aesthetic criteria. More information about each structure can be obtained from Charleson (2015). Sense of place: specific expression of a structure’s natural or cultural environment. Example:

Figure 1. The perimeter structure of Tod’s Omotesando, Tokyo, was inspired by the trunks and

branches of the deciduous zelkova trees in the foreground.

Figure 2. The branching reinforced concrete perimeter structure.

Pleasure: a positive and desirable intellectual, spiritual or sensory experience. Example:

Figure 3. Pleasant curves in the perimeter structure of the Tama Art University Library, Tokyo.

Figure 4. A two way interior frame curved in section and plan creates an experience of softness.

Novelty: an experience that exceeds the expectation of the ordinary. Example:

Figure 5. Westminster College’s novel stepping cantilevered form.

Figure 6. Novel interior structure facilitates the cantilevered floors.

Variety: less than chaotic complexity that increases the potential for sensual engagement. Examples:

Figure 7. The interior of the Philharmonie, Berlin features a diversity of structural and architectural

elements that pass through the foyer space.

Figure 8. Millenium Seed Bank, Wakehurst Place, UK. A variety of vaulted and post-and-beam forms

exudes a sense of peacefulness.

Unity: richness and variety comprehensively integrated into a unified or harmonious relationship. Examples:

Figure 9. The exterior of the Baumschulenweg Crematorium, Berlin is unified by

virtue of its geometry and exposed concrete.

Figure 10. ‘Randomly’ placed Condolence Hall columns introduce a variety of gathering spaces and

contrast with perimeter walls, but are unified by common materiality and the concrete slab roof.

Figure 11. The Louvre pyramid, Paris, whose form is repeated in and unifies the detailing.

Figure 12. A coffered slab whose detailing harmonizes with the exterior pyramidal form.

Figure 13. Triangular recesses on each column face are another

example of the unification of parts.

Clarity: the experience is easily grasped and understood. Example:

Figure 14. In the Portuguese Pavilion, Lisbon, the concrete catenary is clearly

supported by a number of buttressing structural walls within the two end blocks.

Intensity: the depth of feeling experienced. Example:

Figure 15. The form of the Church of the Autostada, Florence, alludes to tents

and the nomadic life of a traveller.

Figure 16. The interior structural elements bring an intensity to the space. They

tantalize by inviting many different readings.

Security: no concern for personal safety. Example:

Figure 17. One feels very secure in this corridor of the Felix Nussbaum Museum yet

simultaneously experiences an intentional and overwhelming sense of imprisonment.

Now that the aesthetic criteria have been defined and illustrated they are now applied to the expressway structures. MACKAYS TO PEKA PEKA EXPRESSWAY The 18 km long expressway is located in a particular landscape. Deliberately avoiding long straight lengths, it winds its way north from MacKays Crossing through a coastal region of gentle vegetated sand dunes and low-lying flat areas, sometimes in the form of swamps. It is a soft gently rolling landscape, devoid of dramatic features like cliffs or ravines, which presents a challenge for designers wanting their landscape structures appearing too fit into the landscape. Kāpiti coast with its sandy beaches lies only several kilometres to the west while equally as close to the east are the medium to steep slopes of the foothills of the Tararua Ranges. Also, the expressway passes through the settlements of Raumati, Paraparamu and Waikanae. The geology underlying the expressway primarily consists of sand with stretches of peat. Sand was the predominant cut and fill material, although rock quarried from Paraparamu was used as fill material for the approaches to the Raumati South underpass. Culturally, the area has a rich history of Māori settlement which is still evident. The concrete structures reviewed in this paper consist of two retaining walls (excluding bridge abutment walls), two foot bridges, ten road bridges, and one of many lengths of screening walls. One or two of each of these structures are reviewed below. Retaining walls Due to the relatively benign topography the expressway passes through there are only two readily visible walls retaining natural material. Both walls that form a cluster just south of the Waikanae interchange retain the remainder of a hill cut into by the expressway (Figures 18 and 19). The walls, with different plan geometries are one above the other with a walking and cycle way behind the lower balustrading. An evaluation of the walls is presented in Table 1. Note that the rating for each criterion is subjective and therefore cannot be considered definitive. Each person will have different personal standards from which to make an assessment based upon their experiences and understanding of landscape structures. However a final average rating can enable comparisons to be made between structures, as is done later. The walls rated well above average in every category. The lowest ratings were for ‘Sense of place’ and ‘Intensity’. In my opinion, to gain a High for ‘Intensity’ the structure would have to be breath taking or awe inspiring, and to achieve a Medium rating would have to be considered exciting. Regarding ‘Sense of place’, to gain a higher rating perhaps the shapes of the walls and or their art work

might evoke the gentleness of the surrounding topography, the presence of the nearby coast, or the steepening and bush clad hills to the east. In my opinion, an average rating of High represents a very commendable achievement.

Figure 18. The retaining walls as seen by a driver travelling north.

Figure 19. The walls photographed from just off the walk way looking south.

Footbridges Only the two footbridges passing above the expressway are considered here. Both are predominately constructed of concrete, although their main spanning structure and cladding is of steel. The first bridge passed under whilst travelling north is the Rongomau Footbridge (Figure 20). The Makarini Footbridge (Figure 21) is approximately 300 m north of the Paraparaumu interchange.

Figure 20. The Rongomau Footbridge as seen driving south.

Figure 21. The Makarini Footbridge viewed when driving north.

The evaluations are summarized in Table 2. Due to the geometrical complexity of the Rongomau Footbridge it rates considerably higher than the more simple and predictable Makarini Footbridge which scores low in ‘Novelty’, ‘Variety’, ‘Pleasure’ and above all, ‘Sense of place’.

Table 1. Retaining walls: aesthetic criteria, comments and ratings.

Aesthetic criteria

Comment Rating Low - Medium - High

Sense of

place

The Māori-like patterns cast into the panels speak of

Māori settlement in the vicinity. The curved walls

respond to the rounded shape of the hill they help

retain.

Medium

Pleasure The walls give pleasure when viewed. They are

attractive from all angles and positions.

Medium

Novelty Curved walls are unusual, their tops slope and they step up.

High

Variety

The walls are off different lengths and curvatures.

They constantly vary in height and feature interesting

patterns cast into the wall panel surfaces that are

different for each wall.

High

Unity Both walls are curved, of the same material and have

a similar language of panel patterning. Both walls,

especially as seen looking north, appear to weave

together. The closer wall diminishes in height with

distance while the opposite happens for the upper

wall. They are very much one composition.

High

Clarity

These structures are clearly retaining walls and their

shapes and geometry are easy to understand and

appreciate.

High

Intensity The walls induce a depth of feeling far beyond what

an ordinary wall straight in plan and elevation would

do.

High

Security

Nothing suggests the walls are weak. Their curvature

would even increase their strength but there are no

obvious signs of strength, such as exposed

buttresses.

High

Average High

Table 2. Footbridges: aesthetic criteria, comments and ratings.

Aesthetic criteria

Comment

R: Rongomau Footbridge, M: Makarini Footbridge

Rating Low – Medium - High Rongomau Makarini

Sense of

place

R: the bridge curves at the western end to flow into the

walkway parallel to the expressway. As explained by

NZTA (2017), the name and design of the bridge

reflects a local story, and the bridge is shaped like the

eels that inhabit the local waters.

M: although its curved profile echoes the sand dunes

along the expressway, near its location the ground is

flat. No obvious local or regional cultural or topographic

links.

High Low

Pleasure R: intellectually and visually memorable.

M: slight pleasure mainly due to the curved

superstructure.

High Low

Variety

Visually solid spanning structures with partially

transparent balustrading. Lighter coloured balustrading

would accentuate superstructure slenderness and

variety.

R: geometric variety in plan and elevation.

High

Unity All elements are of the same colour. Sections through

the abutment, superstructure and the trapezoidal

shaped piers are geometrically similar. The

superstructure springs, almost seamlessly, from its

abutments. All components are linked together by

colour and common geometry.

High High

Clarity

These structures are clearly experienced as bridges

supported on piers and abutments with lower opaque

load bearing elements supporting decks and partially

transparent balustrading.

High High

Intensity R: a variety of thoughts and positive feelings are

experienced by the unusual and attractive curved form.

M: a more predictable and common shape.

High Low

Security

No concern for personal safety when driving under or

walking over the bridges. High balustrading protects

bicycle users. The sense of security is not emphasised

architecturally.

High High

Average High Medium

Expressway underpasses and river crossings Two of the design principles that informed the bridge designs were to be “generally consistent in their form so they register as a ‘family’ and provide some visual continuity within the local environment”, and to “utilise the opportunity provided by multiple bridges to make a system of parts that can be repeated at each location and improve efficiency of construction” (M2PP Alliance 2012). It is therefore unsurprising that the road bridges look very similar. In fact, their superstructures are almost identical but there are some variations in the form of and surface treatment of their abutments. Perhaps in hindsight more emphasis could have been placed on a more context sensitive approach. Due to the similarity of the bridges only one underpass and

one overpass are reviewed, but for these structures a slightly different review approach is required. This is because for these bridges the criteria need to reflect the experiences of two separate groups of people, the users of the expressway, and secondly, people away from the expressway who observe the bridge from a completely different perspective. The Raumati Road underpass (Figure 22) is chosen as a representative underpass. Some underpasses comprise single spans yet the Waikanae Interchange has five. The Raumati underpass differs from most of the others due to its skewed orientation and also by how its end spans are above concrete surfaces that slope from the abutment to the carriageway. These sloping areas adjacent to the abutments contrast with those of other underpasses whose abutments are vertical, such as illustrated by the one span overpass in Figure 23.

Table 3 summarizes the structural evaluation. Notes from other underpasses are included to provide a more complete description of the design variations among underpasses.

Figure 22. The Raumati Road underpass.

This bridge, and all other underpasses rated high for ‘Unity’ and ‘Security’ but not so well for the other criteria. Regarding ‘Novelty’, mention is made of the facing panels’ treatment. All of these panels are 2.1 m deep, and because they are solid, it means that the bridge superstructure is ‘read’ as being very deep. Therefore, rather than appearing slender or light, it appears heavy and chunky, like many other road bridges. This has the effect of reducing, or even negating, a sense of novelty. The same opaqueness of these panels that function as balustrading or safety barriers means that users are unable to see out to the side and to below. This is especially disappointing over a river crossing where users are denied the pleasure of enjoying the river. It also means they are cut off from and are almost completely unaware of the towns they pass through.

Table 3. Raumati Underpass: aesthetic criteria, comments and ratings.

Aesthetic criteria

Comment

O: Observer U: User

Rating Low – Medium - High

Observer User

Pleasure O: the sloping faces from the abutment, a variety in

surface finishes, the sculptural piers and the skew of

the bridge in plan induce a degree of pleasure. The

separation of the expressway into two bridges

introduces light down between them.

Low Low

Sense of

place

This bridge lacks any regional or local references. It

could have been built anywhere in the world. Some

underpasses do have a sense of place. Examples

include rounded river boulders placed under the

superstructure and around piers, and lightly inscribed

Māori motifs on the surfaces of piers.

Low Low

Novelty O: The skewed geometry adds novelty as do the sculpted shaped piers. The change in slope of the superstructure facing panels reduces their visual depth in some natural lighting conditions. Bearings are just visible between longitudinal beams and the cross-head beams.

Low Low

Variety

O: Some variety due to the skewed geometry leading

to different end span lengths. Concrete surface finishes

vary with exposed aggregate near the abutments and

fairface concrete elsewhere.

Low

Unity All detailing is crisp and well attended to.

Fairface concrete finishes help have the bridge

appreciated as one structure. No significant richness or

variety needing unification, yet no discordant notes.

O: in some bridges, hollow slabs, rather than beams,

provide a smooth soffit. All components come together

as a coherent assemblage of parts. The superstructure

connects neatly with the abutments and the tapered

ends to the cross-head cantilever beams over the piers

transition well with the slope of the precast concrete

fascia panels.

High High

Clarity

O: the experience of being near the bridge is easily

grasped.

U: the main clue that one is on the bridge is the white

painted concrete barrier panels.

High Low

Intensity O: No significant sensory arousal. Low Low

Security

O: observers feel secure due to the size of the concrete

members.

U: the solid barriers along the length of the bridge lead

to a very high sense of security

High High

Average Medium Low

Expressway overpasses The aesthetic ratings for the Ngarara Road overpass (Figure 23) and the only other one a few kilometres south, are very similar to those of Table 3. For users on the overpass the ratings are identical. The user experience of an expressway bridge and an overpass is the same - just as unsatisfactory. Only truck drivers and bus passengers are able to see what is happening below. For observers of the overpass, who include the expressway users, the situation, however, is worse. The overpass consists of just one span and so its depth is even more foreboding given the reduced length of the superstructure. However, it seems that the designers were aware of this issue for they have extended the lengths of facing panels at each end far beyond the span length itself. This successfully creates the impression that the superstructure is more than three times longer that what it really is. The superstructure therefore appears far more slender and appears to bridge between the tops of the earthen embankments.

Figure 23. The Ngarara Road overpass north of Waikanae.

This ‘virtual superstructure elongation’ is just as important to mitigate the visual presence of the abutment walls. As seen by expressway users, the walls of each abutment begin near the top of the embankments that are parallel to the expressway and move inwards towards the centre of the expressway to almost meet the edge of the carriageway. By so doing they provide a total constriction of view. A tunnel is created. While some might argue that variety is being introduced, for expressway users a more serious effect is that the walls block the attractive views on either side of the expressway. If the current overpass was replaced by a three span bridge with gently sloping abutment walls following the slope of the embankments then the bridge would both enable distant views whilst framing them. The whole bridge composition would be visually and physically lighter, and more transparent – similar to the vast majority of the expressway length where side views are possible through fine cable and post safety barriers. There may be other locations where visually solid and heavy stabilized earth abutments are appropriate, such as where a constriction might express a ‘sense of place’, like if a road was in a rock cutting, but why at Kāpiti, especially where soils are soft, slopes are gentle and the views attractive? Expressway screening walls Walls are placed alongside the expressway at various locations. One presumes their purposes are to reduce noise disturbance, enhance privacy for local inhabitants, and to block most expressway traffic from their sight (Figures 24 and 25). The designers have obviously tried hard to improve the aesthetics of these walls. This is reflected in reasonable ratings for observers in all categories except ‘Intensity’ and ‘Sense of place’ (Table 4). Those who live near to and walk and cycle alongside the walls have a reasonable aesthetic experience. Expressway users’ experience is not likely to be so positive as indicated by the ratings. Experienced at speed and especially close to the edges of the carriageway, both the angles between panels in plan and their peaked profiles are jarring and disconcerting.

Figure 24. A section of wall near the Raumati Road underpass with the walkway to the left

Figure 25. A length of wall as seen by the expressway user.

DISCUSSION Table 5 summarises the ratings of each of the structures. One of the first observations from the table is that the aesthetic experiences of expressway observers has been privileged over those of its users. This appears reasonable as most expressway observers will be locals who have to live with the expressway, probably for the remainder of their lives, but as noted below it would seem some more compromise is needed, particularly for river crossings. It is no surprise that the footbridges rated higher than the vehicular bridges. It is much easier to introduce novelty and variety into footbridges that are less numerous in a project. Also, the fact that the live loading of a footbridge is so much less than that of a road bridge gives designers more freedom to consider a wider range of options. The main reason for the retaining walls possessing such high aesthetic qualities is due to their unique form. If a considerable length of ground along the expressway had needed retaining it would have been far more challenging for the designers to satisfy the aesthetic criteria so well. This observation can be confirmed by a simple Google image search using the phrases ‘creative footbridges’ and ‘creative motorway retaining walls’. While some wonderful footbridges are displayed there is a dearth of noteworthy motorway retaining walls. It is also instructive to search for ‘creative motorway bridges’. While there are indeed a few inspiring examples, many bridges are blander than those on the expressway. This indicates the difficulty of achieving successful aesthetic qualities for this structural type. In the light of this rough and ready benchmarking against international practice, the expressway bridges are revealed in a good light. In spite of their aesthetic quality ratings being low from an absolute perspective, they compare favourably with international practice.

Table 4. Expressway walls: aesthetic criteria, comments and ratings.

Aesthetic criteria

Comment

O: Observer U: User

Rating Low – Medium - High

Observer User

Sense of

place

The design features that introduce novelty and variety

do not speak obviously of a ‘Sense of place’. However

the angular topped panels might refer to the roofs of

buildings hidden from expressway users’ view, and the

linear patterns could evoke flax leaves and the stems

of bulrushes in adjacent wet lands.

Low Low

Pleasure U: some might experience some discomfort and others

frustration at having their views blocked.

O: At a slow speed the angular profile of the wall is

interesting and an improvement on a constant height

wall.

Low Low

Novelty Precast concrete wall panels are slightly angled in plan

with off-sets at each end (to accommodate vertical steel

posts). The tops of the wall panels are also

asymmetrically pitched or angled in elevation.

Medium Medium

Variety

The top pitches of panels differ. The panels facing the

expressway feature a criss-cross pattern on an

otherwise fairface finish. An exposed aggregate finish

is on the other side of the panels and steel H-section

posts painted green support each end of a panel.

Medium Low

Unity Even though the wall appears fragmented by its

angular up-and-down top profile, it is unified by its

concrete materiality which is either exposed aggregate

or has a linear patterned finish. The wall is perceived

as one wall with everything integrated.

U: my first experience was unpleasant and intense. It

felt like driving past huge saw teeth, or unevenly placed

tomb stones.

Medium Low

Clarity The experience is easily grasped and the form and

intent of the structure is obvious.

Medium Medium

Intensity No sensual arousement apart from users’ possible

negative experiences.

Low Low

Security The thickness and material of the panels conveys

security.

High High

Average Medium Medium

Table 5. The different structures reviewed and their aesthetic ratings.

Structure Ratings

Observer User

Retaining walls High

Footbridges High and medium

Under/overpasses Medium Low

Noise walls Medium Medium

However, some suggestions for designers of future structures to consider are listed below. The term ‘designers’ is intended to include civil engineers, structural engineers, architects and landscape architects. Both engineering and architectural professions are necessary if improved and satisfactory aesthetic experiences are to be achieved. Some of these suggestions are sure to be contrary to clients’ requirements, briefs and budgets. Where they conflict with other design requirements those requirements should be interrogated to find other ways forward. Questions are asked of each criterion that generally did not attract high ratings. Sense of place What inspiration for structural form and detailing may be drawn from the setting of the structure? How might, say the softness and peat-laden quality of underlying soils be expressed in the approaches, abutments and the superstructure? What bridge type best expresses those soft ground locations given an arch bridge might be considered the best response for an all-rock site? How might different topographies on each side of a road be expressed? What if, as on the expressway, on one side there are low sand dunes and coast beyond, while on the other side lie steepening slopes to a range of hills? How might designers acknowledge and celebrate these special landscapes in concrete structures? Might there be opportunity to more strongly reference the Māori occupancy of the past (and present), or other cultural aspects? Pleasure How can bridge superstructures be more slender? How can they be designed to appear less heavy and overbearing? How can more transparent balustrading be designed and yet satisfy safety and other criteria? How might bridge users be enabled to see the landscape features the bridge spans? Novelty What novel aspects can the structure display? Perhaps, and ideally these will arise when trying to accentuate a ‘Sense of place’. How can some of the structural elements be more expressive, of something? For examples of how structures can express something rather than nothing, refer to Charleson (2015). We need to avoid structures that are not expressive at all - just bland! After all, a simple line drawn on paper can begin to express an idea or a context by any variation from a straight horizontal line, such as a slight inclination or curve. Variety What opportunities are there to introduce more variety into the users’ experience without compromising ‘Unity’? The expressway, to some extent, already achieves this as a whole by avoiding long straight stretches of carriageway. For further information about these and other aesthetic qualities “Bridge aesthetics” (RMS 2012) is highly recommended.

CONCLUSIONS Results of the aesthetic evaluations undertaken in this research indicate that observers of the expressway enjoy higher quality aesthetic experiences than the expressway users and that the aesthetic qualities of the two retaining walls and footbridges exceed those of the expressway bridges and walls. In general, the reviews of the structures from this landscape architectural perspective reveal a lack of ‘Novelty’, ‘Variety’, ‘Pleasure’ and ‘Sense of place’. A series of questions are posed to assist designers incorporate these qualities more extensively into future structures.

Overall, the aesthetic ratings of the structures were quite low. Yet a simple international survey of motorway bridges structures indicates that the structures reviewed here can be considered to be of a satisfactory to high standard. This highlights the really difficult challenge for designers operating under many constraints to achieve structures with high aesthetic qualities. In spite of these difficulties, the aesthetic qualities of the two retaining walls and one footbridge on the MacKays to Peka Peka Expressway are considered to be outstanding. This study has not extensively referred to the design guidelines provided by the client nor the design intentions of the project designers. A future stage in this research would be to review all these documents to ascertain how client and designer restraints affected aesthetic qualities and then critique them in order to improve the aesthetic qualities of future projects.

REFERENCES Charleson, A.W., (2015), “Structure as architecture: a source book for architects and structural engineers”, Oxford UK: Routledge. Murphy, M.D., (2005), “Landscape architecture theory: an evolving body of thought”, Long Grove, Illinois: Waveland Press, p. 154. Murphy, (2005a), pp. 160-164. M2PP Alliance, (2012), “Mackays to Peka Peka Expressway”, AAE Lodgement 15 March, rev. 1, p. 65, accessed 11 May 2017 from https://www.nzta.govt.nz/assets/resources/urban-design/mackays-to-peka-peka/docs/m2pp-technical-report-5-section-5.pdf. NZTA, (2017), “Your guide to the Mackays to Peka Peka Expressway”, New Zealand Transport Agency. Roads & Maritime Services, (2012), “Bridge aesthetics: design guide to improve the appearance of bridges in NSW”, NSW Government, Australia, accessed 25 July 2017 from http://www.google.co.nz/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwi_9bHUv6PVAhWIVrwKHUPmDnsQFgghMAA&url=http%3A%2F%2Fwww.rms.nsw.gov.au%2Fdocuments%2Fprojects%2Fplanning-principles%2Furban-design%2Fbridge-aesthetics-guidelines.pdf&usg=AFQjCNGbG75U6ymRyMdid9jGPlXuQ60Lpg.