Quote:
Originally Posted by lrt's friend
Do highway projects also escalate in cost? Or are they more immune since we are building highways all the time and have a better handle on costs.
The positive is that once rail projects are built, we have permanent new infrastructure. It is too bad that rail improvement had little investment between 1950 and 1990, but that was a product of highways being public and rail being private and the railways only saw investment in freight as beneficial to them, until Brightline anyways. At least now, we are finally realizing the benefit of public rail projects.
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Highway projects do escalate in cost, but in general not as much as rail.
Here's a chart, sourced from
The Cost-Benefit Fallacy, a sort of sequel to the seminal
Megaprojects and Risk:
Benefit overrun is a comparison of first-year usage estimates vs actuals. For rail, this is predicted first-year ridership vs actual.
First-year benefits are not always the best metric, usage rates can rise significantly over time, but usage rates for subsequent years can often be difficult to source. You'll note even a first-year usage comparison can only be obtained for a minority of projects.
As you can see, rail projects have an average cost overrun of 40% and an average of 44% less ridership in the first year than predicted. Road projects by comparison stand at 24% and 4%, respectively.
There's no one reason for why this happens. Here are some factors I've seen:
-Your typical road project is smaller than your typical rail project. Road projects encompass everything from two lane non-subgraded country roads to miles long 8+ lane concrete viaducts, and there's a whole lot more of the former than the latter. Plus, you don't need to buy trainsets or wire up high voltage lines along a roadway, but typically do with a new railway. There's a less complexity with smaller projects, less potential unknown factors, so the estimates tend to be better.
-Road projects can be more flexible in their capacity than rail projects. Rail infrastructure has an extremely high base cost, so while a road project can switch between a 6 lane highway and a 4 lane greenway to match predicted usage, a passenger rail project typically requires double tracking. In short, there's a lot of ways to build a road, but only one or two to build a railway, and all of them tend to be on the bigger side. That sometimes leaves you with the only options being either overbuilding your new rail line, or not building it at all.
-Road projects are easier in the design and construction. Cars can travel up and down far higher grades than railed vehicles, and make much tighter turns. That means less earthmoving and digging (almost always the most lengthy part of any transportation project), and more flexibility on location. It's just easier with a road make a swerve and a sensitive area, rather than getting bogged down by public protests or lawsuits.
-Not to put too fine a point on it, but the benefits of rail projects to their supporters often fall outside of a cost/benefit ratio. Reduced greenhouse gas emissions, lower air pollution, better social equity, better city character, some of the biggest advantages of rail transit projects fall outside a simple measure of ridership vs cost. But that's a problem because public funding's availability usually
is defined by this measure. That leaves a lot of incentive for political organizers to encourage, or at least look the other way when an consultant submits unrealistic estimates for cost or ridership.
On the last point, as you can see from the chart most major infrastructure projects use sweetheart statistics to some extent. There's just a little more incentive with rail, because without goosing those the cost vs ridership stats a bit you'd always see rail losing out in the funding game to roads. Which is pretty much what happened in the mid-20th century USA, back when those in power cared a lot less about intangible benefits and so saw little reason to give rail the leg up it often needs.
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