The numbers are startling.

It would cost the Regional Transportation District half as much money to start up nearly 100 miles of enhanced bus service in the northern suburbs as it would to build 11 miles of light rail from Westminster to Broomfield.

That is a preliminary finding, as reported by The Denter Post’s Monte Whaley, from the Northwest Area Mobility Study, an effort by RTD to weigh its options when it became clear it would take 30 years to build the Northwest Rail Line from Denver to Longmont with current revenues.

Preliminary findings put costs of a bus rapid-transit system at up to $300 million to serve up to 27,000 people daily by 2035.

Meanwhile, just extending the Northwest Rail Line from its current, funded destination of Westminster 11 miles to Broomfield would cost as much as $681 million, according to the study. But that extension would only serve some 3,400 more people.

In fact, the study found, extending the Northwest Rail Line from Westminster to Boulder could cost $1.4 billion, a third going to pay BNSF for using its railway.

Yet, as Chuck Sisk, the RTD board member for northwest communities, pointed out, these are only preliminary findings; the study may yield other options.

“The fact is people in the northwest voted overwhelmingly for FasTracks,” Sisk told us, adding, “Is it rail at any cost? Of course not.”

These are only estimates for capital costs, and under that analysis, rail is always more expensive at first. And other factors have still to be measured, such as accompanying economic development.

We’ve said before we want folks in the northern suburbs to get the rail they were promised if possible, and we have been open to the idea of an additional, metrowide sales tax to finish the job.

Another solution could be a statewide tax issue for transportation, preferably user fees like fuel taxes to pay for roads and transit.

But we also agree we can’t have the Northwest Line at any cost.