Staff have proposed either a 25-cent increase in Caltrain's base fare by itself, or a 25-cent base fare increase plus an additional 25-cent increase in the additional zone fares, according to spokeswoman Christine Dunn.
Under the first proposal, the base fare would go up from $2.25 to $2.50, while fares between Caltrain's six zones would remain unaffected.
Under the second proposal, the fares between zones would also increase, from $1.75 to $2.00.
Caltrain officials will ask at this Thursday's Caltrain board meeting in San Carlos for a public hearing to be scheduled on the proposed fare hikes.
Officials have requested a Sept. 4 hearing, which would be preceded by three public meetings on the proposals in late August in San Carlos, Santa Clara and San Francisco.
If either proposal were to be approved by the board, the fare hike would go into effect in January, Dunn said.
The agency's last fare hike, of 25 cents per zone, took effect in April 2007.
Caltrain has recorded increases in ridership in each of the past three years, as well as a record 8.6 percent rise in the past fiscal year, which is attributed to higher gas prices as well as service improvements, Dunn said.
However, she said, Caltrain's fuel costs have jumped 32 percent in the last two years.
Dunn said Caltrain uses 4.45 million gallons of diesel fuel each year, and each 10-cent increase in fuel prices costs the agency $480,000.
Caltrain offers train service on the Peninsula between San Francisco and San Jose, and commuter service to Gilroy.