LYNN – The cost of getting to Boston by train, subway or bus could increase by nearly 40 percent over the next five years as the Massachusetts Bay Transportation Authority (MBTA) wrestles with the agency’s astronomical debt, a consumer protection group reported Tuesday.The Massachusetts Public Interest Research Group (MASSPIRG) conducted an analysis of MBTA finances and determined that the regional transportation system faces several “unhealthy choices” to address a budget deficit between $357 million and $438 million.Two of the most obvious choices are fare increases or service cuts, said MASSPIRG spokesman Eric Bourassa.”These budget gap numbers paint a bleak picture,” he said. “The options available to the T to close the deficits – higher fares and less service, or a greater debt – all would negatively impact ridership.”According to the report, “Derailed by Debt: Unhealthy Choices the MBTA Will Be Forced to Make in FY2009-FY2013,” highlights three primary solutions for closing the budget gap.The report stated that fares would have to increase by at least 38 percent over the five-year projection period. To put this in perspective, a single ride subway fare would rise by 65 cents, from $1.70 to $2.35 on a CharlieCard, or $2 to $2.75 for rides taken with a CharlieTicket.The Link Pass would increase from $59 to $81 a month. A commuter rail Zone 4 pass holder would see an increase from $186 to $257 a month.If the option to cut services instead is selected rather than increase fares, managing the multi-million-dollar debt would require the MBTA to reduce by 50 percent bus and rapid-transit services after 9 p.m. weekdays and all day on weekends, according to MASSPIRG.The report also asserted the service cuts would also reduce up to 20 bus routes, focusing on those that lose the most money; eliminate 50 percent of the commuter rail service after 9 p.m., and 50 percent of the service all day on weekends; and increase peak rapid transit rider congestion by removing one train from each time period before 9 p.m. and on weekends.Services such as The Ride, would likely be eliminated in towns not mandated by law, as would the Suburban Transportation Program.The impact analysis was prepared by Central Transportation Planning Staff (CTPS), which estimated these measures would lead to an annual 18 million loss of ridership.MASSPIRG delivered the report Tuesday to Gov. Deval Patrick’s office.