Vancouver, BC's Seabus was probably the first use of POP in North American transit. Because a lot off the riders were making bus connections with transfer rights the incentive for fare evasion was small. Edmonton opened LRT in April 1978 with a barrier system with ticket booths. In November 1980 we switched to POP. We learned to call the machines 'TVM's' rather than 'POP machines' when a lady sent us a letter warning that if we put POP machines in the stations the floors would get sticky.
As in Vancouver, the initial line had little problem with fare evasion because so many of the passengers had bus connections to make. Not, I should emphasize, that bus drivers check 100% of the passengers. It was just that the odds on being checked were high.
The Denver LRT line/s had the same experience. In both Edmonton and Denver I worked with Marketing to institute 10-ride ticket books to improve convenience for medium frequency riders or families or special events customers. As the rail systems grew, the incentive for fare evasion increased because more trips could be made all-rail. At the same time, this tempted budget trimming to add train hours to the system while holding the number of fare inspectors low. Consequently, evasion blossomed.
So, it takes a multi-faceted approach. Checks can keep fare evasion to 1% or 2% (a check of 1,001 fares on buses between downtown Edmonton and the U of A showed that was about the number of people who showed invalid passes on buses and got past the busy operator). Paid areas need to be defined. Fare media need to offer easy to use alternatives.
Edmonton poster used whimsy to sell Berlin-dimension tickets, the size of a souvenir that I had from Army days . Validators were built in the bus repair shop.
