Navan Rail Line

The figure of €3 bn sounds suspiciously like another P95 estimate: basically, the worst-case path where everything that can go wrong does go wrong. The government has definitely started to use these figures in project communications, probably to avoid accusations of cost overruns when the project is actually completed, but it has the unfortunate side effect of making the cost of any future infrastructure plan look like an enormous, unjustifiable cost.

It's possible to sleep on a bus or a train, something that’s frowned upon while driving ;)

Versus a train, I think the time would be comparable if the line allows the trains to hit their 140 km/h top speed between stations. Google says 22 minutes to drive during off-peak times, up to 35 minutes during the morning rush. I’d predict 30 by train at a reasonable average speed of 80 km/h including stops. A coach would be a little slower than driving (buses are limited to 100 km/h on motorways). Both the rail and bus options also skip the €3.40 in tolls every day (one each way) that drivers would incur to reach M3 Parkway from Navan - that toll is the primary reason this motorway is so quiet.

Daily commuters care more about the predictability of journey times rather than how long that time is: this is where rail wins over coaches, which can’t avoid being stuck in other road traffic. Even if the train took 30 minutes versus the 22 (best case by car), the fact that it was always 30 minutes would tip the balance in favour of rail.

I do think rail would be a better option, but the high cost is a major factor against it, especially as M3 itself cost close to a billion euro and was clearly built to an unneeded scale: the State had to subsidise the concession by a further €17 million after opening as toll revenues didn’t live up to projections (that is no longer the case since 2021).