21 Jun 2024 by Jonathan Raper
Performance statistics measured by the rail industry are very focused on punctuality and cancellations. Look at the Office of Road and Rail Passenger Rail performance report for January to March 2024, and you will see Public Performance Measure – PPM covering on-time arrival at the train’s destination. You will also find reliability defined as the percentage of trains cancelled on the day or pre-cancelled due to last minute resource availability shortage. These statistics drive the way that train operating companies look at performance because they are regulated to do so.
However, these performance metrics do not cover some key aspects of the customer experience. In particular, the use of cancellations to define reliability does not cover a customer’s end-to-end journey experience when the journey is not cancelled. While cancellations are undoubtedly of importance to customers, particularly on low frequency services, the reliability of journeys on the high frequency network means consistently achieving the advertised journey time, delivered at the time it is scheduled to be available.
The bus industry has been focused on measures of reliability suitable for high frequency services for some years and has developed journey metrics that are tracked by both regulators and operators. For a turn-up-and-go, high frequency service, Excess Waiting Time (EWT) is a measure of the increased headway between services when they run late. High EWT erodes trust in delivery to the point where customers choose other modes of travel.
An even more important metric developed by bus operators is Reliability Buffer Time (RBT). This metric is measures the difference between the average real journey time (RJT) and the 95th percentile journey time i.e. the time a journey takes 1 out of 20 times. I used TAPI Rail Performance managed service to extract 20 real journey times between Basildon and London Fenchurch Street for 2B11 headcode service at 15.54 on a weekday between May 20th and 17th June 2024 to calculate this metric as a commuter would experience it.
The average RJT was 37 minutes (the scheduled time) but the 95th percentile journey time was 46 minutes from the time the service was due to depart. Research on RBT shows that customers treat this time as the ’time they should allow’ for the journey so they can rely on it… and in this example the 46 minute journey time is 24% longer than the scheduled time.
The TAPI Rail Performance managed service records all actual times and the expected departure times shown to customers as well as dwell times, and so facilitates the tracking and forensic exploration of these metrics like RBT and RJT. The raw data is available via web for in house browsing and via API so developers can show real journey times in apps and the data is now also available through the Rail Data Marketplace.
The equivalent tracking of RBT by bus operators through the TAPI Bus Performance managed service showed Transport for West Midlands that there were some routes that had values of RBT four times higher than others… and that helped focus attention on those services. High RBT is reputational damage for operators and needs measuring so journeys can be improved.