The hike in diesel fuel costs helped send Providence and Worcester Railroad Co. third quarter profits plummeting 85 percent, according to the railroad's earnings released Monday.

The Providence and Worcester Railroad Co. reported a net income for the quarter of $702,000, compared to net income of $1.3 million in the third quarter of 2004.

The regional freight railroad, which operates in Massachusetts, Rhode Island, Connecticut and New York, also reported a 7.3 percent dip in total revenue, which was $7.6 million in the third quarter 2005 compared with $8.2 million in the third quarter 2004.

The nine months, ending Sept. 30, revealed a 1 percent gain in total revenue for Providence and Worcester Railroad Co. (AMEX: PWX), which said revenues were $20.2 million at the end of the nine-month period in 2005 compared to $20 million reported at the end of nine months in 2004.