service on this line runs every 30 minutes. The Green and Orange Lines operate service every 15 minutes on Monday–Saturday mid-days, but every 30 minutes on weekend mornings, on Sundays, and during evenings. Fares and fare collection The San Diego Trolley operates on a proof-of-payment system. Passengers must have proof of fare (ticket or pass) before boarding. Self-serve ticket-vending machines located at each station sell one-way paper tickets and passes (one day and monthly) on the Pronto Card. Roving transit enforcement personnel conduct random ticket inspections throughout the system. If customers are caught without a valid fare, they may be fined. Based on frequent security inspections, nearly 98% of the 37 million patrons have proper fares. One-way fares are good for up to two hours from the time of purchase. The fare does include a transfer to other routes, as long as it is within two hours from the time of purchase. One-day and monthly passes are sold on the Pronto Card, which costs $2. Passes allow passengers to transfer a number of different transit systems within San Diego County including the San Diego Trolley, MTS Bus, MTS Rapid buses, NCTD Breeze buses, and the NCTD Sprinter (a light rail line in North San Diego County). More expensive premium passes include access to the NCTD Coaster commuter rail line, MTS Rapid Express, and MTS Rural buses. Pronto cards are linked to an account which can store value to be used at any time. The Pronto card uses the "best fare," which is similar to pay-as-you-go. The card will automatically deduct a one-way fare each time it is tapped, and will cap the total fare deducted in a day to the limit of a Day Pass, which is $6. Pronto will also cap the total monthly fare to the same price as a Month Pass, which is $72. The Pronto card must be tapped on a Pronto Card validator (located just outside the paid area of stations), or the QR code must be scanned from within the Pronto App when entering and transferring within the system in order to be validated. Ridership As of the Fourth Quarter (Q4) of 2013, the average weekday ridership on the San Diego Trolley system was 119,800, making it the fourth busiest Light rail system in the United States. Taking overall track length into consideration, the San Diego Trolley transported 2,239 daily passengers per route mile