A bridge too far? A tunnel may be the answer.

2534 Heysen Tunnels 1

 

2534 tunnel google worldBy ERWIN CHLANDA

 

Loss of life and the partial annihilation of the CBD in a big flood, and traffic congestion through The Gap, might be able to be solved with one engineering project: A tunnel through the range (at right).

 

There would be a third, most significant gain: The Gap, perhaps the town’s most splendid landmark and a key site in many Aboriginal songlines spanning the continent, would be restored to its pristine state.

 

It would escape the absurd possibility of having a flyover (two images below) put through the middle of it – one of the engineering solutions proposed.

 

Pie in the sky? Maybe not.

 

The Heysen Tunnels on the Adelaide to Crafers highway (top of the page), below Eagle on the Hill, a Federal and State Government joint venture, are similar in length, 500 metres. They have three lanes each in two “tubes”. The lanes are each 3.5 meters wide.

 

Project Value: $151m in May 2000. That’s small change when considering the utterly unnecessary rail overpass on the South Stuart Highway, costing the Feds $24m last year.

 

And that’s not the only precedent that could work for The Alice, according to the Queensland chairman of the Australasian Tunnel Society, Harry Asche. The other is something similar to the SMART Tunnel in Kuala Lumpur, Malaysia, which is being used for traffic as well as flood mitigation.

 

p2390-gap-flyover-smThis is how it could work: removing the railway line and the highway – both on elevated mounds – from The Gap would double the width of the creekbed which would logically substantially increase the flow rate of the river.

 

Secondly, some of its water could be diverted through the tunnel on the exceptionally rare occasion of a major flow, usually over in a few hours.

 

In such an event Stuart Highway traffic could be diverted through Honeymoon Gap.

 

The highway would be straightened up south of the range and connect with the present alignment not very far from the northern exit of the tunnel.

 

Mr Asche spoke with the Alice Springs News Online when we contacted him. He is not willing to speculate about the cost but says the project is technically feasible.

 

The geology doesn’t seem a problem: The work would be done by a road header (pictured), or where the rocks are too hard, by drilling and blasting.

 

2534 road header 1To have two or more “tubes” is an advantage: In the event of a fire or another accident, rescue crews can gain access from either side.

 

Mr Asche says 24/7 monitoring of accidents needs to be added to the cost of a tunnel.

 

But here, too, the town has an advantage: The fire and ambulance stations are just a few hundred metres up the road.

 

What next?

 

• Calculate the increase flow rate with road and rail removed and the tunnels being an extra channel when required.

 

• Do the figures: There is cost saved for a flood mitigation dam – estimated to cost $30m in 1992 – upstream from the Telegraph Station, regarded by experts so far as the only structure that makes sense. It is symptomatic of the current government that it has done nothing substantial after disbanding a flood mitigation committee, headed by Mayor Damien Ryan, that took a year and a half to recommend a topographical survey of the Todd catchment.

 

• The other saving would be the cost of additional structures being jammed into The Gap to provide more road lanes.

 

As for the reaction of Aboriginal traditional owners, it is impossible to predict them, given the contradictory views by various clans about traditional responsibilities for sacred sites in this town.

 

However, what can be put on the table is this: The women’s sacred site Walyatje Therre, at the proposed dam site, upstream from the town, would remain untouched.

 

p2390-gap-flyover-2There would be no need for levee banks in town which would scar it, some of its sacred sites, and wouldn’t work in a major flood.

 

The Gap would have the unsightly rail and road removed and could be enjoyed how it was millennia ago, a major gain for many Indigenous people in The Alice.

 

And the lives saved by effective flood mitigation are likely to be those of Aboriginal people, several of whom have drowned in past floods.

 

 

UPDATE 10.45am May 4:

 

The Department of Infrastructure, Planning and Logistics said this morning that topographic data for the upper catchment has been obtained and will be used to produce a digital elevation model (DEM).

 
The department is currently in the process of updating the Alice Springs flood model with the new DEM. Once complete it will better inform government in regards to the viability and effectiveness of potential flood mitigation options.

 

 

2535 Erwin Gap OKUPDATE Saturday, May 5, 10.20am

 

I’ve taken some measurements (that’s me in the photo): The creek bed is 50 metres wide at  its narrowest point.

 

The railway embankment is 9.2 meters wide, measured from the rock; the footpath 1.8 meters; the highway 9 meters; and the eastern footpath, indulging the slope of the embankment, is 4.5 meters. That’s a total of 24.5 meters which makes Rod Cramer’s statement that the traffic infrastructure takes up “no more than about 30%” of the creek bed pretty close to the mark.

 

However, add to that the tunnel tubes available for occasional flood water use (14 meters for four road lanes and 6 meters for 2 rail tracks) and you get 20 meters.

 

Together with the recreated full width of the Todd’s bed, with the traffic infrastructure removed, you get 94.5 meters of flow width compared to 50 now – close to double of the current width.

 

– ERWIN CHLANDA

 

 

 

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22 Comments (starting with the most recent)

NB: If you want to reply to a previous comment, start your comment with this notation: @n where n is the number of the comment you want to reply to.
  1. Psuedo Guru
    Posted May 7, 2018 at 1:43 pm

    Save Alice Springs. A major flood will devastate the town. Floods since the 1870s are minor events.

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  2. Mabel
    Posted May 5, 2018 at 10:00 pm

    @ Dr Ongo: Doris isn’t one of them!

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  3. Bev Emmott
    Posted May 5, 2018 at 7:52 pm

    A tunnel through the range at the gap: When the water comes it spreads right across the plain.
    I would think that a tunnel near The Gap would just be another place for the water to flow through. The bridge into town is the best access in a flood so the solution would be to build up not through.
    If the tunnel had a road as high as the rail track and all the way down through The Gap it might work, but not if the tunnel was at ground level.
    Trouble with Alice Springs is that it is built level to the river bank, fine most times until flood comes, then quite a bit of the town is under water. We are lucky the big flood has not happened for years.
    Another way is to deepen the river so that it takes more water before the water spreads over the roads.

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  4. Charlie Carter
    Posted May 5, 2018 at 4:47 pm

    There is another road tunnel through a hill near Byron Bay on the north coast of NSW.
    The M1 motorway goes through it. I estimate it is about 200m long.
    I take the discussion seriously, or at least parts of it, with the primary purpose being to open up The Gap again to improve the flood flow.
    Even 30% seems worthwhile, and the cost benefit should be able to be calculated, and compared with other flood mitigation proposals.
    However, the concept of allowing flood water through the tunnels is ridiculous.
    One of the important functions would be to ensure N-S access for emergencies during floods.
    Rod Cramer is correct that Honeymoon Gap would also be impassable in a flood event.
    I don’t agree with Domenico that ideas should not be discussed, but he seems to be confusing discussion of an idea (this) with discussion of a Government proposal (the gallery).
    Any serious look at the future of Alice would not project a great population increase. “Industrial Development” just ain’t gunna happen.
    Two lanes of road in one tunnel, and the railway in another (perhaps with an emergency road lane beside it) in another should suffice.
    To write off Aboriginal approval seems premature, given that The Gap would be freed of its main desecrations.
    Of course it will never be pristine, Alex, but it would be a hell of a lot better.
    Dr Ongo, of course the river slows and spreads, you would expect that once it is free of The Gap squeeze.
    Research by Water Resources in the 80s showed that bed level causeways have little effect on flow.

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  5. Dr Ongo
    Posted May 5, 2018 at 12:36 pm

    There is a dam just south of the gap, some people call it a causeway. Anyone who has floated down the river on a lilo would know that the river slows and spreads as you come near the causeways. If they are lowered and especially if the couch and buffle grass are removed then the sand can wash through and the river will be deeper, allowing more water through quicker.

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  6. Erwin Chlanda
    Posted May 5, 2018 at 11:34 am

    “Dr Ongo”: Thank you! I know at least five of them. I will speak with them, and I will report the results. I will also seek your advice.
    ERWIN CHLANDA, Editor

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  7. Dr Ongo
    Posted May 5, 2018 at 8:29 am

    Since whitefellas came here Erwin there is not a single Aboriginal person with unchallenged authority, however it is well documented who the apmereke-artweye and kwetungurle are, and these are the people who have a the right to talk for country.
    Naturally the government and others often don’t want to talk to them, divide and conquer is their methodology. Also custodians often don’t agree to damage to their sacred sites and country.

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  8. Erwin Chlanda
    Posted May 4, 2018 at 12:44 pm

    Hi Domenico: No confusion here. As you seem to be pointing out, community leaders proposing “viable options, each backed up with factual data” are pretty thin on the ground. To wait for them to spring into action is silly, and complaining if they don’t is a waste of time.
    The initiatives need to come from the people, whom the politicians are meant to be serving, by doing as they are told.
    The Alice Springs News Online is far from presenting a “solution”. We are presenting facts from authoritative sources and background from our story archive.
    As you can see, a discussion has started, with further contributions of fact, as a result of which consultation can occur – from the people to the pollies, not the other way round.
    The government imposed “preferred solution” elsewhere has just taken a big hiding, as we all have seen.
    By the way, if you can name an Aboriginal spokesperson with unchallenged authority on the subject, please let us know.
    ERWIN CHLANDA, Editor

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  9. Posted May 4, 2018 at 12:22 pm

    All of this was discussed and researched in the mid 1980s, with the (then) NT Department of Works conducting tests in the bed of the Todd River at Heavitree Gap for suitability of construction of a four-lane flyover.
    The NT Government announced in May 1986 that it would proceed with a roundabout at the north entrance to Heavitree Gap, alterations to South Terrace, and a new bridge just downstream of, and replacing, the Casino Causeway (Taffy Pick Crossing).
    Public consultation was undertaken during 1987 about road developments through Heavitree Gap, with ultimately a model of a four-lane flyover displayed for public comment late that year.
    Then we got hit with the Easter flood of 1988 and the NT Government completely changed its priorities in favour of a full flood mitigation dam at Junction Waterhole north of town. We all know where that ended up.
    Moreover, Alice Springs failed to grow anywhere close to the extent originally envisaged 30-plus years ago, so the pressure was off the government to continue with any of these plans with the exception of the Tom Brown Roundabout and nearby road alterations built in 1994.
    A tunnel or tunnels through the main range isn’t a realistic prospect, and I doubt it makes economic sense. The Heysen Tunnels near Adelaide were probably the most cost effective option for road transport in that vicinity.
    The fact is that the west side of Heavitree Gap has long been compromised and can never be returned to a “pristine” condition. It’s also the path of least resistance for practical and economic reasons for any future developments, as far as I can tell.
    I can’t see the point in “restoring” Heavitree Gap into a “pristine” condition by punching tunnels through the ranges. It’s a nonsense proposition.
    In the long run there will probably be a need to widen the road through Heavitree Gap, and I expect that will most easily be achieved by a bridge structure that perhaps could include the existing laneways.
    However, it’s difficult to see any chance of that happening for a very long time.

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  10. Posted May 4, 2018 at 11:43 am

    @ Erwin. Sorry, but you seem to be confusing consultation with “debate”, which is what happens on these pages.
    By consultation with the community, I meant that NTG and Council so-called “leaders” propose viable options, each backed up with factual data.
    For example, has anyone bothered to ask the local Traditional Owners how they feel about a tunnel?
    Community consultation is not about throwing up a contentious idea, set up as a “solution”, for us all to get into a scrap about.
    I’d have thought they would have learnt something after the debacle over the siting of the proposed Indigenous Art Centre.

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  11. Trevor Shiell
    Posted May 4, 2018 at 10:34 am

    The reality is that the CBD is where it is because it was built to service the telegraph station several decades ago and this is no longer a major item in development of the town.
    Its future is well south of The Gap around Brewer because this is where future industrialisation will have to be – preferably in the form of an integrated transport hub of road, rail and air, as has happened interstate.
    If this were not the preferred option, the jail would still be at the Women’s Hall of Fame, the airport would still be be to the old cemetery the power station would still be next to the golf course.
    Now also the TOs would like the Art Centre South of the gap, as probably medical facilities will be, etc etc etc.
    How many times has the Mall been re invented? Make it a dedicated tourism precinct as has happened at Harndorf, in the Adelaide Hills, and re direct residential development to Brewer where the future action will have to be, thus reducing the pressure on The Gap.
    Other commercial facilities will follow the employment.
    The opportunity cost of the Kilgarrif nonsense will become obvious in future years as that was the obvious place to sell what is possible here and induce people to invest here, with employment to follow.
    This was the very epitome of short term thinking and pork barrelling.
    Re route the heavy traffic will take from Queensland via the Outback Way to WA direct to Brewer via Arltunga, opening up the East Macs to further tourism development.
    Start anew based on relevant circumstances, not obsolete history.
    Are we going to retrofit the current area North of The Gap with an electric network to suit the thousands of electric vehicles, including electric trucks, heading our way, or should we direct them to where their refuelling capacity is, (or will be further developed), as the solar initiatives develop?
    Maybe with a bit of futuristic thinking The Gap may not need to be developed at all and become an iconic part of a visitors unique experience here, as it always has been.

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  12. Rod Cramer
    Posted May 4, 2018 at 9:30 am

    If this is a serious discussion, which is hard to accept given some of the comments, let’s stick to facts.
    Firstly, while I vigorously agree both the the rail and road embankment should be removed, that won’t “double” the river bed – they currently only occupy no more than about 30% of the original bed of the Todd.
    Secondly, when are people going to realise that in the event of a major flow in the Todd (and from time to time, some not so major ones), you have Buckley’s of getting to Honeymoon Gap from the north, let alone driving through it!
    Not withstanding, a tunnel option should be on the table, the flyover, which several presenters in 2006? lied to us about, should not.

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  13. Psuedo Guru
    Posted May 4, 2018 at 8:53 am

    Chinese engineers to sort CHEAPEST and BEST answer to Alice Springs flood mitigation.

    View Comment
  14. .bruce
    Posted May 4, 2018 at 8:45 am

    Alice Springs does not flood once in a blue moon. The river bed is so dry it has not even a soak anymore. And that hill is Caterpillar Dreaming. It is sacred to the Arrerente People of Alice Springs.

    View Comment
  15. Erwin Chlanda
    Posted May 4, 2018 at 7:03 am

    Hi Domenico: “Serious community consultation?” You are taking part in it right now, right here.
    The Alice Springs News Online is now in its 26th year. We’ve published 17,242 readers’ comments since July 29, 2011, each of them moderated to ensure decorum, and giving a voice to the broad spectrum of opinion in our community. This is not counting Letters to the Editor nor frequent comment pieces by guest writers.
    We reach an average of 18,000 readers (see the regularly updated web traffic boxes on every page). AND we’re locally owned.
    ERWIN CHLANDA, Editor

    View Comment
  16. Domenico Pecorari
    Posted May 3, 2018 at 10:07 pm

    This has got to be a late candidate for April 1st?
    I have yet to see traffic jams through The Gap and there are less expensive ways to increase river flow and reduce flood levels in the town area.
    How about some serious community consultation instead of another dictatorial debacle?

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  17. Richard Bentley
    Posted May 3, 2018 at 9:23 pm

    There are seven tunnels in the world over 28km long and up to 57km.
    So this is clearly possible.
    I liked the idea of raising the rail over the road but with a tunnel you could still take the rail higher and bridge it over Bradshaw and other roads south of the gap. Returning the gap to its natural state is well worth considering.

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  18. Posted May 3, 2018 at 1:53 pm

    A tunnel through the main range (including on the eastern side, too) is an idea almost as old as the hills 🙂
    Conversely there have also been a number of proposals over the years to dam Heavitree Gap; and indeed, in 1952, it was suggested that all the gaps and gorges should be dammed to create an enormous reservoir stretching through the MacDonnells.
    That idea was suggested just over a decade before the discovery of the Mereenie aquifer.

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  19. Laughing
    Posted May 3, 2018 at 1:10 pm

    This is why we can’t legalise recreational weed.

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  20. Concerned Citz
    Posted May 3, 2018 at 11:31 am

    What a ridiculous idea and of course costs to who, us the locals in our taxes. Just move the Cultural and Art Centre out to DPC and leave everything else alone PLEASE.

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  21. James T Smerk
    Posted May 3, 2018 at 11:28 am

    Are these mob having a laugh? When it floods not only is The Gap flooded but the road past The Gap and then some. You would need to raise the whole highway for many kms!

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  22. Graham Tjilpi Buckley
    Posted May 3, 2018 at 10:32 am

    A no-brainer solution to our micro engineering dilemma is to engage the Chinese engineers who have just had their 55km bridge from Hong Kong to Macau opened.
    They went over and under the water for this simply marvellous achievement.
    Surely they would have an idea or two!

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