The CBC reports a problem from two Presto users who were billed wrongly for trips miles from their actual location on a different transit system. Specifically, riders who boarded the subway at Wilson Station, and then transferred to the 52 Lawrence West bus using Presto cards with TTC monthly passes were billed for a MiWay trip at Westwood Mall.

Problems with Presto placing a rider or charging wrongly for trips have been known for quite some time. Some cases are due to GPS errors, and others due to limitations of a rule-based system for calculating fares.

Before the TTC moved to the two-hour fare in August 2018, riders could find they were billed for a new fare in cases where they made a legitimate transfer connection. This could occur for two reasons:

The connection occurred at a location that was not defined as a valid transfer point between routes within the Presto system. Typically this happened when vehicles were short-turned or diverted and the transfer happened at a location Presto was not programmed to recognize. Transfers between cars of the same route could trigger a new fare charge.

The vehicle did not accurately “know” where it was at the time a card was tapped because of a GPS error, and so Presto misinterpreted the transfer as a new trip.

Riders using passes on their Presto card were not affected by these problems because they paid a fixed charge, but pay-as-you-go riders would be charged a fare they should not have paid. Unless riders checked their transaction history, they would never notice the problem.

With the two-hour fare, the controlling factor is the time, not the location of the tap, and so the whole transfer point issue disappeared.

However, recently Presto extended its functionality so that TTC riders could use their card on neighbouring systems such as York Region Transit and MiWay, and this created a new way that Presto could fail. If a TTC bus reports its location in a “foreign” location, Presto could assume that they were on a different transit system, and charge for a trip there.

The specific case reported by the CBC is particularly interesting because Westwood Mall is a legitimate location on the 52 Lawrence West route. TTC buses run outside of the City of Toronto on some routes and riders can use their Presto cards to pay the outside-city fare on a TTC vehicle. However, it is clearly impossible that someone could get from Wilson Station to Westwood Mall in 6 minutes.

This brings us to the problem of how Presto deals with bad GPS data.

The plot below shows GPS data from the 52 Lawrence route taken from the TTC’s vehicle tracking system. There are 10,000 vehicle data points included here, and they clearly show the geography of the route, its branches, and the garage trips to and from Mount Dennis Garage. The blue dot at the northwest end of the route is at Westwood Mall.

However, the plot looks somewhat different if we zoom out to include all data. The cluster of dots in the lower central part of the plot is the main part of the route, but there are many dots far away from the route. When these are plotted on a map, locations range from Wasaga Beach to the middle of Lake Ontario. What does Presto do when it “sees” a tap at such a location? Does it try to map this to the nearest point that is legitimate for the route? Would a tap far northwest of Toronto be mapped to Westwood Mall, the nearest point on the 52 Lawrence West route?

There are two major issues for Metrolinx here, and this is not the trivial problem the agency presents.

First, GPS errors happen and Presto needs to deal with them. This is not a problem with the TTC, a favourite whipping boy for Metrolinx, but with GPS systems generally. This will become more important as riders whose “home” systems with local fare discounts such as monthly passes or two-hour fares regularly cross boundaries to other systems. Even with some sort of fare integration (a rat’s nest of policy and funding problems in its own right), there will be challenges if the tariff involves zones or some distance-based charge. There must be a reasonableness check built into the system to detect travel patterns that don’t make sense for a rider. Even so, things will go wrong.

The second problem is that Presto needs to acknowledge that these problems do occur and clean up its Customer Service practices. Only after this incident became a media issue did Presto actually do something, three months after it occurred. Indeed, their original advice to the riders was that they should contact MiWay to get a refund even though (a) they were on a TTC bus and (b) the fare system is Presto’s, not MiWay’s. Evading responsibility should not be the first response to a customer complaint.

Transit has a hard enough time fighting for riders. It should not be hobbled by systems and procedures that work against good service.