As part of the DfT Bus Open Data Service (BODS) project, a new TransXChange 2.4 profile – the UK Passenger Transport Information Profile (TXC-PTI) – was commissioned to establish a common standard for exchanging UK timetable and schedule data. The initial draft documentation, running to 66 pages, was issued on 30 April 2020.
TransXChange is complex, in large part because there are numerous ways to represent identical information, with each software supplier choosing the approach that suits its own systems. The schema guide for TransXChange 2.4 runs to 210 pages; the GTFS specification, by comparison, runs to 21. We looked at the draft profile from the perspective of the people who will have to consume BODS data: those trying to assemble a usable national dataset from many producers using very different systems.
There is a lot to like. National Operator Codes are mandated, service coding becomes consistent across operators and regions, and version numbering requirements are clear.
Our concern is with what the profile still permits. Data that is declared as a default and then overridden in a more specialised element should be avoided wherever possible: it forces every consumer to handle multiple cases and to form its own view of what compliance means. We would rather see all trip validity information held within the trip itself, and routes and journey pattern sections kept simple – even at the cost of slightly larger files.
The usability of BODS data determines its value. If producers and consumers disagree about how to interpret it, and there is no arbitrator of what “correct” TransXChange looks like, consumers will go elsewhere – to unofficial GTFS feeds, or away from transport apps altogether. Timetable data is genuinely complex, and handling compliant data from every producer is markedly harder than handling it from one. The answer is to simplify the standard as far as it can be simplified.