As the number of people riding the metro area's two light-rail lines soars, so does the number of passengers who take rides without paying.

New figures to be released at Wednesday's Met Council Audit Committee meeting show that between 8.3 percent and 10.4 percent of passengers on the Blue and Green lines bypass the fare box, up from between 3.4 percent and 4.7 percent when the last Light Rail Fare Evasion Audit was conducted two years ago.

Metro Transit's 2015 ridership figures showed 10,620,284 rides were taken on Blue Line and Green Line ridership in 2015 was 12,383,173. Metro Transit uses Automatic Passenger Counters, or overhead sensors inside the train to measure movements into and out of light-rail cars, to estimate ridership.

It was not immediately clear how many times passengers rode without paying, said spokesman Howie Padilla.

Metro Transit says 1,470 citations have been issued this year along with more than 8,000 warnings.

Both light-rail lines allow riders to board without passing through a turnstile or showing a conductor a ticket. Riders are supposed to swipe their electronic fare cards at readers on a rail platform or purchase a ticket from a machine. Passengers are required to have a ticket while on a platform or train or have proof that they swiped their card.

Auditors arrived at their percentages of nonpaying riders by surveying 915 passengers who were required to show proof of payment. Some riders are allowed to ride free. They include children under 5, personal care attendants traveling with a passenger with a disability and travelers shuttling between Terminal 1 and 2 at the MSP Airport.

The number of non-paying riders rose substantially on the Blue Line, which runs from downtown Minneapolis to the Mall of America in Bloomington, the audit found. Estimates show that the number of riders who skip paying on the Blue Line rose sharply from between 2.6 percent and 3.6 percent two years ago to between 7.6 and 11.8 percent, according to data collected between April and May 2016 when compared with a similar audit conducted in September and October of 2014.

The fare evasion rate on the Green Line, which runs between downtown Minneapolis and St. Paul, rose slightly but was comparable to the rate recorded in the 2014 audit. The most recent estimate showed that between 8.4 percent and 10.8 percent failed to pay. That compares with a rate of 4.6 percent to 9 percent identified in the 2014 audit.

Fares range from 50 cents within downtown zones to $2.25 at peak travel times. Failure to pay can result in a $180 fine.

A report last year from the Met Council found that the transit agency loses out on fares of $4,600 to $6,400 a week on the Blue Line while those on the Green Line ranged from $11,100 to $21,800 a week. The new audit did not calculate the amount of lost revenue.

Fare dodging scofflaws on the Blue Line are most likely to ride during the midday period and weekends while Green Line cheaters were most common at night, during the evening rush and on weekends. Compliance was highest on both lines during the morning peak periods. The Blue Line saw a drop in fare evasion at night while the Green Line saw a drop during midday hours the audit showed.

Fare dodgers on the Blue Line were most common on weekends between Target Field and U.S. Bank Stadium stations. The segment between Cedar/Riverside and Lake Street had high numbers of non-paying riders during the evening rush hours, weekday midday periods and on weekends while fare evaders were common on weekends along the segment from American Boulevard to Mall of America, the audit said.

On the Green Line, fare evasion is highest between Snelling and Western Avenues, ranging from 14 to 22 percent during evening rush hours, nights and weekends. Consultants who performed the audit also found high numbers of fare evaders between Union Station and Capitol/Rice Station on weekends.

One reason given for the big rise in fare evasion on the Blue Line may have come due to a change in enforcement by Metro Transit police. In the spring, the agency said all first-time offenders would be given a warning instead of a fine.

"This policy change could have made some riders more willing to risk riding without proof of payment knowing that a warning would be issued, rather than a citation," the audit said.

Conversely, fare evasion on the Blue Line in 2014 may have been suppressed as Metro Transit hired more officers ahead of the June 2014 opening of the Green Line. Officers checked fares with more frequency during the first half of 2014 which may have deterred riders' willingness to board without paying during the summer and fall, the audit concluded.

Police have stepped up fare enforcement between 2014 and 2016. Two years ago, officers on trains asked 1.4 million riders to show they have paid. Through September they have checked 1.6 million and are on pace to hit 2 million by Dec. 31. The number of citations issued in 2016 was not immediately available.

Metro Transit has about 100 full-time and a pool of part-time police officers whose duties involve canvassing trains and platforms looking for fare flouters.

Metro Transit's fare evasion rate is in line with peer transit agencies in the United States, Canada and Australia that have similarly-constructed transit systems, with rates between 5 and 15 percent, the audit said.

Some systems, such as Chicago, New York and Los Angeles require riders to pass through a barrier before boarding a train, as opposed to the honor system used by Metro Transit. But that has not eliminated the problem of fare evasion in those cities.