New Auckland harbour crossing

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pdh

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#3459578 7-Feb-2026 19:41

If we look at what charging input's needed to add a 2 km of range to a bus...
The busway stops are 1-5 km apart and 7 km to get over the bridge.

I believe a sedan-sized EV needs about 100 kWh (of battery) to do 1000 km - so that's 0.1 kWh per km.
I'd assume a bus would need 10-20 times that - so maybe 2 kWh /km ?

At 350 kW transfer rate, 4 kWh (2 km x 2 kWh/km) would take about 40+ seconds - plus time to connect, ramp up & down and then to disconnect.
A minute wouldn't seem long - if passengers were getting on/off.

To get power for 7 km (eg: the bridge), would take about 2.5 minutes - that might feel a bit tedious.

Whereas 15 minutes at the end of a run would be good for 40+ km (only one set of overheads).
And the single charging site would be hugely easier to build & maintain.

RunningMan

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#3459583 7-Feb-2026 20:51

@pdh - Bjorn Nyland did a bus test. https://youtu.be/ovJVNSRAoWw?si=SPLI53V7VjWuhqIm&t=1260

Combination of urban and motorway it used 695 Wh/km, so roughly a 1/3 of what you estimated. Even for a larger bus, perhaps half of your estimate would be about right.

pdh

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#3459600 8-Feb-2026 02:41

> Even for a larger bus, perhaps half of your estimate would be about right.

Well, I'd like to see some real-world figures with passengers included.
I know that EV pickup trucks are not fond of towing trailers - it halves their range.
So adding in 6+ tons of passengers will be worse than an empty bus.

Anyone know how well Auckland EV buses do ?
You would think that AT would be praising their performance widely - if they are pleased...

RunningMan

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#3459606 8-Feb-2026 08:10

On stop start journeys like a bus, the weight will have less impact due to regen braking - what is used to accelerate is gained when braking at the next stop. A lot of the drag from towing is the trailer aerodynamics, which remain unchanged when the weight is within the bus.

pdh

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#3459749 8-Feb-2026 13:26

Regen breaking is nice - but there are significant losses.
Good point about trailer aero - but (PU+trailer) decreased mileage is seen in urban (ie: low-speed) use as well.

I believe Auckland's ev buses are 12 m (double-decker) and 13 or 13.5 m (single-decker).
I can find lots of data on their expected (hoped-for) range - but none on what they actually achieve.
Take that as you will.

OK - I fell back on the dreaded Ai to locate some real-world ev bus data:
(I like Perplexity because it gives me sources which I can verify.)

From a Dutch study (100 buses over 10 months), they got 1.15 kWh/km for 12m and 1.63 for 18m.
(www.sustainable-bus.com)

Given that Holland is a bit flatter than Auckland is, but probably gets a bit colder - I'd say swings and roundabouts.
Their data is likely quite attributable to us.
I's suggest that their 18m single-decker is closer to our 12m double-decker in weight if not aero.

Perplexity comes up with another dozen studies - from Bonn, Knoxville, etc.
All in a range of 1-2.5 - depending on length, load, temperature & hilliness.

So I don't think I was all that pessimistic in my guesstimate...

RunningMan

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#3459763 8-Feb-2026 15:44

pdh:[snip] Regen breaking is nice -

No, it's not. You'd be requesting a repair if it did.

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gzt

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#3462691 18-Feb-2026 16:41

"“There’s a range of decisions to be made about the funding of that project. It is in theory a project that should be able to pay for itself.” Brown said today that big decisions about a second harbour crossing or tolling should be made together with Auckland, and not by government agencies working in secret."

https://www.nzherald.co.nz/nz/auckland/wayne-brown-says-9-auckland-harbour-bridge-toll-unacceptable-to-aucklanders/CHT2GM2OEZBPLDPNUCC3HGV7N4/

Auckland City and the government working together in secret instead? Edit: I'm just too irritated by the whole traffic cones tag team thing to be posting.