How much would a busway in the NWTC cost (ballpark estimate)?
An interesting question to answer would be figuring out a ballpark cost for a surface busway in the NWTC.
The section Everton Park Link Road to Bald Hills Station is about 12 km in length. Parts from Carseldine to Bald Hills overlap with an existing proposed busway corridor so the cost could be either attributed to this project or the existing one.
Let’s attribute the cost to this proposed NWTC Busway, to be conservative.
NWTC Busway Cost Estimate
Based on a NSW cost/km of $36.3 million/km, we arrive at a figure of ($36.3 million/km x 12km) = $435.6 million.
Personally, I think this is a bit low. There will be a lot of other major infrastructure constructions happening elsewhere in QLD at the same time, and the effect of this will be to push the price up.
Let’s 2x the estimate to provide some room for variation.
$435.6 million x 2 = $871.2 million based on NSW estimate.
Let’s use a different starting point for the estimate and see where that lands. In 2012, $36 million was set aside for the extension of the SEB from Eight Mile Plains to School Road Rochedale. In 2024 dollars this is about $50 million/km (RBA inflation calculator).
$50 million/km x 12 km = $600 million based on QLD estimate.
We can also use a NZ Estimate to again converge on a ballpark figure (Northwest Busway).
NZD $4.6 billion / 18 km = NZD $255 million/km (this project has to cross water or harbours, hence the higher cost).
$255 million/km x 12 km = NZD $3.06 billion. (About AUD $2.83 billion at May 2025).
Discussion
Coming back to the original question of How can we strip out the cost while also servicing the need for better PT?
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From this it seems a surface option would come in at around $1-3 billion, or about 3-7x less than the tunneled rail options ($7-10b) or the Gympie Road Toll Tunnel ($10b).
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Even if the figure is a bit off, the margin between these options and the tunnels (road or rail) is very large. The costs could be much more, and yet still be ahead.
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There appears to be little need for tunneling if a surface BRT or LRT mode is chosen, as the corridor has already been preserved, and these modes can handle a gradient better than Heavy Rail can.
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Even if you assume a worst-case scenario and must tunnel under Chermside Hills Reserve entirely for environmental reasons (~ 1.5 km) the short tunnel length plus the overall low cost of the project estimate - you could probably include it and still keep the overall project cost still comparatively low versus alternatives.
Notes
BRT Northwest T-Way
Gateway Upgrade South and South East Busway Extension, Transport and Main Roads
Newsletter February 2012
RBA Inflation Calculator
NZTA Northwest Busway (NZ)
Australasian Bus and Coach
Northwest Rapid Transit Busway construction start date revealed