On Stationless Bike Sharing in Sydney

Since I have moved to Sydney, which is to say, very recently, Sydney has seen the emergence of stationless bike sharing. I saw this in China in May, and now it is here. Technology deploys very quickly these days. I signed up for the first entrant, Reddy Go quickly, and gave them a deposit, but didn’t get around to trying to use it til last week. I also registered for oBike this weekend, after getting a 10 free rider voucher (Voucher Code SHARE) for signing up.

Not Reddy, No Go.

A broken Reddy-Go
A broken Reddy-Go

I said “trying to use it” as I was not successful. My first attempt was during the week. I had a breakfast appointment on Kensington Street and was in Chippendale, a nice residential area. It seemed like this would be a good opportunity to use the service without running into too much vehicle traffic, which makes long distance cycling very dangerous. Now biking in Sydney (NSW) is officially discouraged through helmet laws and lack of facilities (and shrinking at that) and heavy fines, though it is officially encouraged by words on plans. I wouldn’t let my kids ride in traffic, as the car drivers are more aggressive than in the US. But Chippendale is mostly traffic calmed.

I pulled out the app, scanned the bar code, and was told via the app, that sorry, this bike cannot be used. I don’t know why. I retried it a couple of times and walked to my destination.

Yesterday, my oldest son saw a Reddy Go, in Alexandria Park,  and tried to climb it and ride, but it was locked. Fortunately I had the app. I tried again just to see if it worked, since the kids had been bikeless for a few months.  It would not unlock. I subsequently noticed it was vandalized, and the spokes on the back wheel were bent out of shape (not accidentally). I reported this via the app.

O, a Bike.

A dirty OBike
A dirty oBike

Well, I signed up for oBike as well, having obtained a coupon card. In Alexandria Park, I saw an oBike, maybe I will try that. It was filthy, as if someone had taken it dirt-bike riding. Unlikely. I saw another oBike. Someone had piled dirt (I hope it was dirt) on the seat. Pass. Finally I saw a clean oBike, tried to unlock that. It actually worked. oReka.

My oldest son put on the helmet (I hope no lice) (probably violating terms of service), and rode around the park. Then my younger son tried it, but his legs were too short. I tried it. I adjusted the seat (which was easy, as these are fairly new bikes, not rusted out yet), put on the helmet, and rode. It rode fine, a bit heavy, with no obvious gears (but a bell, where the gears should be), so it tired my legs more than it should have. After a few minutes I ended the ride. Now how to lock it. I eventually discovered this is a physical mechanism. I put the helmet back somewhere (this is not at all clear where it should go). And left it. I hope it was properly checked out. I have not received a nasty-gram, so I assume I am fine.


A pile of dirt on an OBike Seat
A pile of dirt on an oBike Seat

So this vandalism thing is a problem. In Minnesota, the bike shares were all station-based, so everything was tidy, and it seemed vandalism was a minimum. Perhaps it is something in the Australian (or Sydney) character that leads to the additional vandalism compared with Minnesota? Perhaps it is just because they are randomly placed and not station-based.  There have been news stories lately about bikes in the rivers. Perhaps Sydney-siders or Australians just dislike bikes, the way they dislike immigration by boat. Despite the massive number of shared bikes in China, it didn’t seem to be much of an issue there. Perhaps because of higher utilization, or it is more of a a biking culture, or perhaps because the communist Chinese are more respectful of property than capitalist Australia?

Next Steps

Finally, a successful ride
Finally, a successful ride

The next steps are probably mostly steps rather than rides. I may ask for a refund from Reddy Go, still debating whether to give them another chance. I will test oBike a few more times, but the protected bike lane network is Sydney is not terribly useful to me. (The walk to work wouldn’t be a bad ride, iffy in a few places, mostly around Redfern where there are many pedestrians, but it’s not a bad walk either).

Positions in Robotics at University of Sydney

In addition to the post-doc I advertised yesterday, two other positions might be of interest:

(1) Research Fellow in Robotics and Intelligent Systems

Centre for Robotics and Intelligent Systems
School of Aerospace, Mechanical and Mechatronic Engineering
Faculty of Engineering & Information Technologies
Reference No. 1632/0817

(2)  Lecturer / Senior Lecturer in Robotics and Intelligent Systems

Centre for Robotics and Intelligent Systems
School of Aerospace, Mechanical and Mechatronic Engineering
Faculty of Engineering & Information Technologies
Reference No. 1633/0817

Both positions include “Transport and Logistics” as a potential application area.

Postdoctoral Research Associate in Transport Networks. Closing Date 11:30pm 19 November 2017  

School of Civil Engineering
Faculty of Engineering and IT
Reference no. 779/0417A

  • Join an organisation that encourages progressive thinking
  • Be valued for your exceptional knowledge and experience in Transport Networks
  • Full-time fixed-term for 3 years, remuneration package: $106k  (which includes base salary, leave loading and up to 17% superannuation)

About the opportunity
Applications are invited for the appointment of one Postdoctoral Research Associate (Level A) in the School of Civil Engineering, within the Faculty of Engineering and IT at the University of Sydney. The position will support the research and leadership of School of Civil Engineering in the newly launched Transport Engineering program.

The successful applicant(s) will help build the new research group headed by Professor David Levinson to further the analysis of Transport Networks, understand the relationships between Transport Networks and Land Use, and consider the implications of changing Transport Technologies on optimal Network Structure.

Applicants should hold a PhD in civil engineering or a related field. They should be able to demonstrate high quality research in the area of transport networks, geo-spatial analysis, and econometrics. Demonstrated ability to publish research outcomes in high-quality international journals is also essential. Since the position will require frequent liaising with government and industry, applicants should demonstrate strong communication skills.

About you
The University values courage and creativity; openness and engagement; inclusion and diversity; and respect and integrity. As such, we see the importance in recruiting talent aligned to these values in the pursuit of research excellence. We are looking for a Postdoctoral Research Associate who:

  • has a PhD in civil engineering, or related fields,
  • conducts high quality research in the area of transport networks, geo-spatial analysis and econometrics,
  • demonstrates ability to publish research outcomes in high quality international journals, and
  • possesses strong communication skills as will be required to liaise with government and industry stakeholders.

About us
Since our inception 160 years ago, the University of Sydney has led to improve the world around us. We believe in education for all and that effective leadership makes lives better. These same values are reflected in our approach to diversity and inclusion, and underpin our long-term strategy for growth. We’re Australias first university and have an outstanding global reputation for academic and research excellence. Across 9 campuses, we employ over 7600 academic and non-academic staff who support over 60,000 students.

We are undergoing significant transformative change which brings opportunity for innovation, progressive thinking, breaking with convention, challenging the status quo, and improving the world around us.


The University of Sydney encourages part-time and flexible working arrangements, which will be considered for this role.

For more information about the position, or if you require reasonable adjustment or support filling out this application, Monika Browning, Lead Talent Acquisition Consultant, on +61 2 8627 6562 or monika.browning@sydney.edu.au

If you would like to learn more, please refer to the Candidate Information Pack for the position description and further details.

To be considered for this position it is essential that you address the online selection criteria. For guidance on how to apply visit: How to apply for an advertised position.

Closing date: 11:30pm 19 November 2017

The University of Sydney is committed to diversity and social inclusion. Applications from people of culturally and linguistically diverse backgrounds; equity target groups including women, people with disabilities, people who identify as LGBTIQ; and people of Aboriginal and Torres Strait Islander descent, are encouraged.

If we think your skills are needed in other areas of the University, we will be sure to contact you about other opportunities.

The University reserves the right not to proceed with any appointment.

Selection Criteria

Candidate Information Pack

To Apply, Go Here.

A Busful of Knowledge: On Going from the University of Sydney to the University of New South Wales

There are a few universities in Sydney, the University of Sydney of course, is the most important (revealing my bias), and the University of Technology Sydney (UTS) is nearby, but the University of New South Wales (UNSW) also has a very strong reputation in Civil Engineering and overall, and really isn’t that far away, nothing compared to Berkeley vs. Stanford. Together they can and should make this region a technology powerhouse in the same vein, if not to the same extent, as Silicon Valley or Boston’s Route 128.

The universities are only an hour apart by walk (17 minutes by car on the shortest walking route), but the transit connections are circuitous and nearly 40 minutes. Look at the images. On the top is the relatively direct walking path, just a bit over 5 km. On the bottom is the shortest travel time path by transit, 37 minutes and far out of the way.  Perhaps if we want to encourage interaction, we should make interaction easier. Keep in mind not everyone has a car, especially students, and especially people who commute by train or bus, and taxis are still expensive.

Imagine how much more powerful the region could be if the researchers could more seamlessly interact and students easily cross-enroll and attend classes. Now I realize these are rival institutions established to be competitive, so there are limits to getting along. On the other hand, a more direct bus route seems like a good place to start.

Sydney Transport/Urban Twitter/Blogosphere Meetup

Sydney Transport/Urban Twitter/Blogosphere Meetup – Friday Sept, 22 (6pm) at Hotel Sweeney’s 236 Clarence St, Sydney NSW 2000, Australia

Come one, come all.


Roderick Distinguished Lecture

Rodd Staples, Northwest Rail Link
Rodd Staples, Northwest Rail Link

Roderick Distinguished Lecture

Thursday 31 August 2017

Join us on Thursday 31 August 2017 for the second Roderick Distinguished Lecture for 2017 featuring the Sydney Metro Program Director for Transport for NSW, Mr Rodd Staples. presenting an insight into the Sydney Metro project, his path to such a role and the opportunities available for civil and other engineering graduates to help deliver the transport infrastructure required of a modern city.

Sydney Metro is Australia’s biggest public transport project, with 31stations and 66km of new metro rail.

This project comes at a time of the launching of the Transportation Engineering major within the Faculty of Engineering & IT, which provides students with the opportunity to embrace the mathematical and engineering methods required to plan, design, operate and manage the infrastructure necessary to achieve safe, economical and environmentally sustainable movement of people and goods.

Professor David Levinson who has recently joined the School to lead the implementation of this new major, sees it as an exciting time to be in a city where there is currently a generation’s worth of major transport infrastructure projects occurring simultaneously.


Rodd has almost twenty years experience in transport and infrastructure, across both government & private sectors. With tertiary qualifications in civil engineering & finance, Rodd has worked across a mix of senior executive, project management & technical leadership roles with a core career focus on transport project planning, development and delivery.

“The opportunity to work on a city-transforming project with such a dedicated team is a privilege and one that I am very proud of,” Rodd says.

“We are delivering a new metro system with the customer as its focus which will help transform public transport in Sydney.”


Thursday 31 August 2017

Open from 5:00 for 5:30pm start, followed by refreshments and networking from 6:30pm


PNR Lecture Theatre No 2, Faculty of Engineering & IT, University of Sydney


This event is free but please CLICK HERE to register or contact Malcolm Boyd (see details overleaf)


The Roderick Distinguished Lecture Series

The Roderick Distinguished Lecture Series brings the leaders of industry and government to the University to present to the civil engineers of tomorrow the challenges and opportunities which they and their organisations face and the role that civil engineering plays in their work environment

The Roderick Lectures are an initiative of the Council for Civil Engineering Sydney, an industry advisory group formed to assist the School of Civil Engineering to deliver world-class education and research through an inclusive program of engagement between industry and academia at all levels.

The Roderick Lectures are promoted widely to the students as well as the industry network of the School of Civil Engineering

The Roderick Lecture series acknowledges Professor Jack William Roderick who, as Head of School from 1951 to 1978, initiated programs of engagement with industry to build and to augment the teaching and research programs of the School through the Graduates Association and the Civil Engineering Foundation.

For more information

Malcolm Boyd| Executive Officer | Council for Civil Engineering Sydney
T 0412 797 479 | E malcolm.boyd@sydney.edu.au

The forgotten station |Honi Soit

The transportist gets a shout out in The forgotten station by Simon Coleman in Honi Soit, the University of Sydney newspaper. The article concerns Redfern station, which we talked about earlier in Sydney train stations need two exits. An excerpt below:

An artist’s impression of a future Redfern station. Image: NSW Government / RedWatch.
An artist’s impression of a future Redfern station. Image: NSW Government / RedWatch.

40 per cent of USyd students use the station to commute to campus, and the University expects the student population to increase by 26,000 to 75,000 in the next two decades. Director of campus infrastructure services Greg Robinson has labeled Redfern Station “inadequate” while lobbying the state government unsuccessfully for light rail and metro, according to the Sydney Morning Herald. In 2015 the University lost out to Waterloo for a new metro station as part of the second harbour crossing, and the proposed West Metro is unlikely to go anywhere near the University. Three years prior, in 2012 UNSW prevailed over USyd for a light rail link. More recently, the state government has canceled light rail planning for Parramatta Road (and given Labor’s lack of  support) it is unlikely to happen anytime soon. Given the absence of planned alternative transport options for the University, Redfern Station looks set  to become increasingly important.

Previous government studies (obtained by the RedWatch community organisation under freedom of information laws) have shown that Redfern’s capacity and accessibility could be increased while preserving its heritage. The original entrances on Lawson Street could be closed, and a modern concourse with two staircases and lifts to every platform (removing the bottlenecks of the old cramped stairs)  built at the opposite southern end of the platforms.  The new concourse would have an eastern entrance at Gibbons Park near the apartment towers, and a western entrance at a pedestrianised Little Eveleigh Street or Ivy Lane. This western entrance would provide a direct walk to campus and pedestrian access far less cramped than Lawson Street.  As University of Sydney Professor of Transport Engineering David Levinson notes on the Transportist website, the western entrance would reduce backtracking and save at least a few minutes of walking to campus.

I would hope that not merely would there be a new “southern” entrance to Redfern, but that the “northern” entrance would be retained.

9 Barriers to Walking in Sydney

I am a pedestrian in Sydney, living in a car-less household, so I have had a few months experience in the pedestrian environment. As nice as walking in Sydney is, walking in Sydney should be nicer. For a city with such high densities of people and shops, such a large number of parks, doors on the street, and gorgeous weather, and such terrible internet service driving people from their homes, walking should be the dominant mode. Yet there are barriers to living the motor-free lifestyle here (and undoubtedly elsewhere). Some that come to mind.

  1. At Broadway, for instance, the Pedestrian is not allowed to cross on this side of the street, and is instead forced to cross two roads (or maybe three) to cross one. Is this really safer, running the pedestrian through more potential vehicle conflict points.
    At Broadway and City Road, for instance, the Pedestrian is not allowed to cross on this side of the street, and is instead forced to cross two roads (or maybe three) to cross one. Is this really safer, running the pedestrian through more potential vehicle conflict points.

    T-Intersections Intentionally missing crosswalk markings (and pedestrian signals) are quite common, especially at T-intersections, where pedestrians might only have markings and a signal on one side. While this undoubtedly makes cars go faster (the presumed purpose for this), it makes the walker’s life more miserable, reducing choice and potentially adding travel time. For longer distance trips, backtracking can be avoided by crossing upstream where the signal is available. For short distance trips, this is inefficient. The largest T-intersection I have encountered where this is an issue is City Road at Broadway, where to get from the east side of City Road to the north side of Broadway (which houses a nice shopping mall) requires crossing both streets instead of just one.

  2. Fences. Walking midblock is strongly discouraged on some roads. Presumably for safety and for traffic flow, but still creating a chaffingly regulated environment for the pedestrian who wants to cross the shopping street.

    A regulated pedestrian environment (Hume Highway in Ashfield)
    A regulated pedestrian environment (Hume Highway in Ashfield)
  3. Obey

    OBEY Pedestrians must obey traffic signals or risk getting run over. While almost all of the Pedestrian Actuation (Beg) Buttons work, the phasing of traffic signals is so chaotic as to be nearly unpredictable as to when the pedestrian has right-of-way without a light. The pedestrian phase is extremely, needlessly short, just enough for pedestrians already at the corner when the light changes to make it across on the green walking man, not enough for someone not there, even when the car phases would make it safe for pedestrians to cross. Drivers only look at traffic lights, not for context, so if you are in the crosswalk (marked or otherwise) you will very much risk getting hit (or at least the ire of the driver) if you do not have a green walking man providing moral and legal support. In many cases these are absurd.

    For instance the figure at Thai Tha Hai restaurant.

    I think I can make it across, even if the standing man is red.
    I think I can make it across, even if the standing man is red.
  4. Uneven sidewalks. For a variety of reasons, most sidewalks appear original, although wheelchair curb-cuts have been retrofitted in most places. While roads are periodically resurfaced, the sidewalks, which were likely fairly even when first poured, have unevened with the heave and ho due to poor construction, changing soil conditions, trees, recent construction and the like. Except for the few sidewalks that have been shaved, this leads to tripping hazards. While these hazards are easily identified (send out some interns), it won’t be solved unless someone develops a multi-million dollar robot to ride all the Sydney sidewalks and provide a report, with a large construction contract on the other end.
  5. Shared paths. Many sidewalks are marked as shared paths with bicycles. This isn’t as much of a problem for the pedestrian as it might seem, since so few people bike. That is a problem for other reasons.
  6. Circuity.
    A commute in Sydney
    A commute in Sydney

    Much of the network is circuitous (see [1],[2],[3]), missing links abound. I previously noted the lack of railway crossings, but there are other issues on the street network. I haven’t tested whether this is especially bad here compared to other places, but subjectively it is noticeable. So for instance my trip from home to work more or less as shown in the image could be much straighter than it is, were there a southern/western crossing of the tracks at Redfern station.

  7. Crowding. While pedestrian crowding is not common on most sections of sidewalk, there are times are places where this is a problem. (In the map, the path to and from Redfern Station gets crowded at peak times). Crowding is a problem for several reasons. Pedestrian speeds are slowed to the speed of the slowest traveler, so overtaking is required. The sidewalks are narrow in place, worse on trash collection days, when the rubbish and recycling bins are out. The crowding is especially a shame given the use of space to store empty cars on streets, space that could be reclaimed for more productive human movement.
  8. Lawson St. and Everleigh St. The navigation sign is correct, and there is nominally a shared zone. Spot the mistake.
    Lawson St. and Everleigh St. The navigation sign is correct, and there is nominally a shared zone. Spot the mistake.

    Navigability. While soon our Augmented Reality glasses may make navigation an irrelevancy, in the meantime, I often try to figure out where I am. This requires looking at my phone because there are not street signs visible to pedestrians. The signs are aimed for autos, and on one-way streets for cars (which are still two-way streets for pedestrians), the signs all face the direction the autos are moving.

  9. Fumes and Noise. Cars and especially trucks and buses produce fumes and noise and other externalities that increase the unpleasantness of walking and lower the pedestrian’s expected lifespan. While electrification will eventually do away with both fumes and noise, trucks will be the last surface vehicles to electrify, so this will likely be a feature on the roads for decades. Given the rate of construction in Sydney, many of these are especially large, loud, and polluting construction-related vehicles.

All of that said, there are plenty of nice parts. Some of the best features of walking in Sydney are below:

  • There are some pedestrian only streets (e.g. Kensington, shown)
  • There is a lot of traffic calming within shopping streets and neighborhoods. (The effect of the traffic calming is to push more traffic to the signalized arterials, where it is controlled, but now more congested than it otherwise would be.)
  • Drivers almost always obey the marked crosswalks if a pedestrian is waiting to cross (though what constitutes ‘waiting to cross’ is a bit ambiguous). (They will not yield at unmarked crosswalks unless the pedestrian is in the street, and even then only reluctantly and with ire.)
A pedestrianized street in Chippendale. Kensington Street.
A pedestrianized street in Chippendale. Kensington Street.
A more supportive pedestrian shopping street in Summer Hill, with a pedestrian crossing table.
A more supportive pedestrian shopping street in Summer Hill, with a pedestrian crossing table.

Closing the Cahill Expressway at Circular Quay

Map of Cahill Expressway, Red line indicates section under discussion in this post.
Map of Cahill Expressway, Red line indicates section under discussion in this post.

The Cahill Expressway in Sydney, the city’s first expressway, opened in 1958, connecting the Eastern suburbs to the Harbour Bridge. After the Harbour Tunnel opened in 1992, traffic was halved, the section’s Eason or being eliminated. Looking at a map, you can see the Harbour Tunnel and Harbour Bridge approaches join north of the Harbour, and basically form an upside-down V-shape, with the Circular Quay section forming a cross, the segment turning the upside-down V into an A.

Traffic counts for the Cahill Expressway at Circular Quay are given for 2012 as about 20000 average annual daily traffic in each direction. While certainly non-trivial, this is also not a lot for two lanes in each direction, equivalent to a four-lane arterial. And when the system is working, all of this traffic has alternative routes, as the route is topologically similar to the classic Braess Paradox.

The Braess Paradox observes that under certain circumstances an additional link increases total travel time, and is dysfunctional, because of the difference between the costs that travellers pay and the costs they impose by congesting others. While it is hard to prove such cases in the real world, there is no reason for this link to exist in the post-Tunnel configuration except as a backup when the Harbour Tunnel is closed or constricted to divert traffic to the Harbour Bridge.

Circular Quay Railway Station, Cahill Expressway on the top deck.
Circular Quay Railway Station, Cahill Expressway on the top deck.

If this section of the Cahill were to be removed, many of its access and egress links could be removed as well, creating additional space and sunlight in the constricted central business district. Southbound traffic would decide north of Sydney whether to diverge for the East or West and then take the Bridge or Tunnel, with no recourse except for city streets. Northbound traffic from the East would take the tunnel to cross the Harbour or exit onto city streets. The operators of the tunnel should be pleased.


Suppose the Circular Quay section were closed. The expressway lies on the upper deck of a double-deck elevated structure, with an elevated railway (the under-rated John Bradfield‘s City Circle, completed in 1956)  immediately below. So the whole structure cannot easily come down. Instead the expressway deck can be repurposed, much like New York’s High Line and other infrastructure reuse projects, as a pedestrian overlook (there is already a sidewalk) on the north side, with the south side hosting restaurants and open-air cafes with a gorgeous view of the Harbour.* I am sure urban designers could come up with some lovely watercolour renderings.

Views like this from the Cahill Expressway at Circular Quay (photo from the train deck below)

While all of this undoubtedly requires study and many, many consultant contracts, it is really easy to test the actual traffic effects (and would make a nice Master’s Thesis project). Close the ramps for a few weeks “for repairs”. This must happen from time-to-time anyway.  Perhaps there is a ‘natural experiment’ coming up, or recently passed, when this happened. Monitor traffic elsewhere in the system. Evaluate the consequences.

The hypothesis is that traffic conditions are no worse overall (system travel time is unchanged or lower), though selected links may in fact be worse off while others are improved. Given the reduction in merges and diverges, I suspect more links are improved than worsened.

If this hypothesis is borne out, there is less total travel (fewer vehicle kilometres traveled) in the city, travel is faster, and most travellers are better off.

In recent decades there has been a trend for cities to close obsolete freeway sections. San Francisco famously took down the Embarcadero Freeway for instance, opening up the waterfront. Seoul removed the Cheongyecheon freeway and restored a river. There have been others. While removal of this section of the Cahill is not likely to have the same effects, as the elevated railway will remain, it still could be beneficial.  Proposals to demolish the entire Cahill, which bisects major parks the Botanical Gardens and the Domain have also been discussed, though burying them under air rights park seems a far simpler and less controversial proposal, and less like to strand the Harbour Tunnel.

Aerial Photo (via Apple Maps) of Cahill Expressway at Circular Quay, facing south. Red marks indicate extent of section.
Aerial Photo (via Apple Maps) of Cahill Expressway at Circular Quay, facing south. Red marks indicate extent of section.

Update July 28: A reader writes:

I think you are seriously wrong about the Cahill Expressway and its utility.

It is effectively the artery that feeds and drains the eastern side of the CBD for we who live on the north side (and who I might add paid for it!) and without it the eastern side of the CBD would be near impossible if not extremely inconvenient to access. It cannot be accessed from the tunnel and otherwise requires traversing the city not fun normally and a nightmare right now.

And I think it is a lot prettier – if that can ever be used about 1950’s engineering – than the much loved EL in Chicago and other insertions into older cities to make them work.

And you can at the very least watch the NYE fireworks from it! Or pre 911 you could.

– apart from anything else it is part of JJC Bradfield legacy and that is by popular consensus untouchable!

My response

Fort Street Public School
Fort Street Public School.  A school surrounded by freeway ramps. They are very elegant and nearly perfectly circular ramps (and must be fun to drive).

I am referring only to the section on Circular Quay. How hard would it be to connect  Bridge Street only to the tunnel? I know everything takes too long and costs too much, but I bet with a concerted effort, if there weren’t any significant underground utilities, this would be under a month.  This configuration is only the way it is  for historic reasons (the Bridge was first), no one would configure it that way now.

Cahill AADT (at Circular Quay) 40k 2-ways (4 lanes 10k/lane)
Harbour Tunnel AADT 90k AADT (4 lanes 22k/lane)
Harbour Bridge AADT 160k AADT (8 lanes (1 bus only), 20k/lane)
A better argument for keeping it might be that the Harbour Tunnel is more congested than the Bridge. But surely they are in equilibrium because traffic has sorted itself out, and will do so with any other change, and road changes would be reflected in different effective catchment areas and changed patterns (longer distance trips might use the bridge to the Western Distributor to the Cross City Tunnel instead of the Harbour tunnel for instance. And with all of the development going west of the city (rather than East, where the Ocean lies), shouldn’t traffic from the east be steered away from the Bridge toward the Tunnel)
Now I guess Kirribilli is more difficult to access via the Tunnel than the Bridge, but isn’t that what the ferry is for?
Of course the irony of Bridge Street leading to the tunnel is also a worthwhile reason.
I will leave the aesthetics to the eye of the beholder, but the structure wouldn’t fully come down unless there was a solution for the trains.



* A single lane passage for emergency vehicle could be maintained if necessary.