I did some more number crunching and as it turns out the cost to construct SkyTrain: Expo Langley have not really changed.
The cost estimate of $2.9 billion for Expo Langley in the
Hatch Preliminary Cost Report is in year of expenditure (2022 dollars) which accounts for it is absurdly high; within the same report, the cost for SkyTrain: Expo Langley was also estimated at $2.45 billion in more recent dollars (2016 dollars). The cost estimates also include a generous 25% contingency allowance, which is applied to construction, design and management. Meanwhile, a 20% contingency is applied to property purchases.
The last time we got a cost estimate for SkyTrain: Expo Langley was in the
2012 Surrey Rapid Transit alternatives analysis. This analysis estimated Expo Langley to cost $1.8 billion (2010 dollars). This estimate applied a 20% contingency to property purchases, but applied no other contingencies.
If we apply the generous 25% contingency to the SRTAA estimate and adjust that to 2016 dollars, the cost ends up at approximately $2.44 billion: almost the exact same as the current estimate.
Essentially, the entire 'increase in cost' is the addition of that 25% contingency. Other than that, the costs have remained the same
So why is TransLink trying so hard to push the $2.9 billion number in our face? I think they are interested in making the public think that the cost has significantly increased. After all, in September 2017, they
formally took a position in favour of LRT. You wouldn't want public sentiment to get in the way of that.