Public mass-transit systems must be responsive to commuters’ concerns and strive to become as user-friendly as possible if they are to have any chance at achieving long-term viability.

That is why it is so encouraging that Palm Beach County’s Palm Tran bus system and the Tri-Rail commuter trains have promptly adjusted their operations to address some of South Florida’s new transportation realities.

On Monday, Palm Tran added two routes and activated 36 other route and schedule changes that had been suggested by passengers in the three months since the countywide bus system launched its greatly expanded service.

At the same time, Tri-Rail opened its $2.6 million Mangonia Park station, which became the northernmost terminus of the eight-year-old railroad that links Palm Beach, Broward and Dade counties.

The 18th and newest Tri-Rail station is intended to serve central Palm Beach County and to provide commuters with access to the Veterans Administration hospital in Riviera Beach.

The additional station will require revising the schedules of all trains by from five to 30 minutes, so riders are advised to pick up a copy of the new timetables.

The same advice holds true for passengers of Palm Tran, which has altered several of its schedules to coordinate the buses with Tri-Rail trains and added buses in areas where ridership has exceeded expectations.

South Palm Beach County residents in particular should welcome the changes, which will put more peak-hour buses on the busy Florida Atlantic University-Town Center Mall route and provide additional service to Century Village west of Boca Raton. Some low-ridership routes have been eliminated.

The commendable efforts of Palm Tran and Tri-Rail to fine-tune the regional mass-transit network are in marked contrast to the negative, parochial attitude being demonstrated by government officials in Dade County.

Last month, the Metro-Dade Commission voted to withhold its annual $976,000 contribution to the Tri-Rail budget. If the decision stands, it could jeopardize the future of the railroad, which receives similar subsidies from Palm Beach and Broward counties.

Three Tri-Rail board members attempted to pay a courtesy call on newly elected Dade Mayor Alex Penelas last week in Miami, but Penelas snubbed them. Even more dismaying, the delegation later was told it may have inadvertently violated the Florida Sunshine Law by failing to advertise the meeting and open it to the public.

Dade’s shortsighted approach on this issue is sounding a discordant note in an otherwise harmonious and promising effort to build a regional transportation network suitable for growing South Florida.