A group of elected officials from throughout San Bernardino County want the Metro Gold Line Foothill Extension Construction Authority to consider possible alternatives to a long-planned 12.3-mile extension of the commuter train from Glendora to Montclair, saying the extension could hurt public transit in other areas.

A letter sent Dec. 21 to Gold Line officials cites a 25 percent decline in Metrolink ridership at the Covina station since the March 2016 opening of the Gold Line station, four miles north in Azusa. Because Gold Line gets more money from taxpayers, it can offer cheaper fares than the prices charged by Metrolink.

“If a similar reduction in ridership on the Metrolink San Bernardino Line occurs because of new Gold Line service, this would inevitably constitute a reduction in overall service for communities east of Montclair that do not have access to the new Gold Line option,” according to the letter.

“This would constitute a failure of public transit to serve our communities,” the letter continues. “To truly achieve our goals of mode shift and widespread adoption of public transit, such systems must complement each other — not compete.”

The extension project recently was split into phases because of rising costs. And the letter, signed by local, county, state and federal officials, also raises concerns over the phased approach now being taken by the authority, suggesting the strategy could lead to service disruptions, delays and significant cost increases without any long-term guarantee of service.

In November, the Authority voted to build the line in two phases, after anticipated costs rose 38 percent, from $1.5 billion to $2.1 billion.

Officials attribute the rise in cost to tariffs imposed on imported steel by the Trump administration, a hot economy that’s driving up wages, and a market flooded with proposed rail and transit projects in which bidders can set their own price.

The decision pushed the opening of new stations in Pomona, Claremont and Montclair from 2026 to 2028.

The line will now end 4 miles short of the Montclair Transcenter, where the Gold Line was meant to tie together pedestrian-friendly residential and commercial development.

The change in strategy also triggered a need for a supplemental environmental impact report, which gives the public an opportunity to weigh in.

The letter, sent as part of this process, was signed by Rep. Pete Aguilar, D-Redlands; Assemblywoman Eloise Gomez Reyes, D-Grand Terrace; County Supervisors Janice Rutherford and Josie Gonzales; Upland Mayor Debbie Stone; Rancho Cucamonga Mayor Dennis Michael; Fontana Mayor Acquanetta Warren; Rialto Mayor Deborah Robertson and Redlands Mayor Paul Foster.

The authority will review all comments and respond after the public comment period ends Jan. 4, said Lisa Levy Buch, authority spokeswoman.

“We haven’t had a chance to review them and to talk about them internally yet, so we will be doing that as part of the process,” Levy Buch said.

Although voters approved funding for the extension through the Measure I half cent sales tax in 2004, county officials are now asking whether a Gold Line extension is the best way to achieve that connectivity, considering the rising costs and potential impact to taxpayers east of Montclair.

“Given the significant cost increases for the additional Gold Line phases, we are compelled to ask if it is now time to examine different options and objectives that will achieve the same goal,” according to the letter.

Though the letter does not specify another option, the San Bernardino County Transportation Authority has been promoting its Arrow passenger rail service as a possible alternative to existing commuter rail services in the region.

The service, which is expected to start in 2021, will run smaller, cheaper and more fuel efficient trains called Diesel Multiple Units, on the same tracks as larger Metrolink trains, from downtown San Bernardino to the University of Redlands.

Running diesel trains would not require the construction of new track, which is required with the light rail system. Also, trains would arrive every 30 minutes, said Otis Greer, director of legislative and public affairs for SBCTA.

But, Greer said, they are not asking the Gold Line to study the potential use of DMUs. Instead, they are asking the agency to consider the impact to Metrolink and possible remedies.

“Everybody supports connectivity,” Greer said. “Given what we’ve seen from the bids and cost, is this the right way to do it? And if there’s another way to do it, shouldn’t we consider it?”