Monday, August 02, 2010

Real-time information: need for, reliability and management

Real-time information has been a growth area for Melbourne’s trains, trams and major bus routes. Although less important than the service basics of coverage, span and frequency, it is still appreciated by passengers.

Available and accurate real-time information can mitigate the effects of service disruptions, particuarly on the rail network. Some passengers may choose to change or defer their trip, reducing loadings on scarce train replacement buses. And where services are delayed, reliable information allows passengers to make better use of their time, especially if the station or stop is near a shopping area. Advising of services just ahead eases crowding by spreading loadings across several trains (especially if just after a cancellation) or improving the efficiency of transfers at major stations. Hence good real-time information potentially offers substantial operational and customer service benefits.

Real-time information can vary from manual staff announcements to automated position reporting systems that transmit their data to information displays on station platforms or mobile phones. As staff rely heavily on automated systems, this item will concentrate on these.

Printed timetables are simple and reliable


The need for real-time information varies across the network. I believe there are three factors (reliability, urgency and trust) that determine whether real-time information is justified or not.

Consider a suburban bus route that caters mainly for local shoppers. Passengers may not need to connect with another service or be particularly time-sensitive. Buses are almost always on time and cancellations are rare. Printed timetables fairly reflect actual times and are trusted by passengers. Low urgency, high reliability and high trust make real-time displays a frill rather than a necessity, and in any case the per passenger cost is high if installed at quiet stops.

Suburban railways are quite different. More passengers are time-sensitive, expecially those who need to change to a bus or have fixed work times. Even a ten minute train delay can increase end-to-end travel time by 30 or 40 minutes if a bus is missed.

Even allowing for measurement changes, rail delays approximately trebled since 2003. Punctuality declined from 96-97% to around 85% network-wide. It is lower again during peak periods and on long lines served by the troubled Siemens trains (around 75%). Customer satisfaction also fell as patronage rose faster than service levels, causing crowding and delays. High urgency, lower reliability and falling trust all make real-time information a high priority on the train system, second only to network strenghtening measures that increase capacity, frequency and reliability.

In between are the major bus and tram routes. Here heavy traffic and long routes can increase variability. The city-bound routes have a large commuter function, while the orbital routes feed passengers to railway stations and major trip generators. Again real-time information is desirable, providing extra assurance, especially on orbital routes where the bus might be starting its run 60 kilometres away.

The installation of real-time information in Melbourne has generally followed the above priorities. About the only exception is the busier bus corridors that offer above-SmartBus span and frequencies but provide only fixed timetables at stops.

Unreliable information can reflect poorly on a network

Reliability The extent to which an information system is worthwhile depends on whether its content is useful, provided when the passenger needs it, and can be relied on.

Required standards for the latter are high; if 99% of trains run (as is frequently attained in Melbourne) and information displays are 99% accurate then there is just as much chance of the information being wrong as the train being cancelled.

To be fit for purpose, measuring and reporting equipment (such as passenger information systems) should be sufficiently accurate to show variations in the item being measured without introducing substantial errors or uncertainties of their own. Hence in a system where 99% of services run, information systems must be operational and accurate (in this case faithfully indicating which services have been cancelled) for 99.9 to 99.99% of the time.

Information system reliability may fall during service disruptions, but should always be at least an order of magnitude better than the reliability of the underlying service. This increases trust that information is accurate (despite problems the service itself is experiencing).

In Melbourne some SmartBus displays at stops, ‘next station’ displays on the new Siemens trains and ‘next train’ displays at stations are particularly at risk of not meeting availability and reliability standards (in contrast the 1980s AVM system used for trams appears more reliable).

An inconsistent quality of information can make a transit service appear less reliable than it actually is (and undeservedly lower its reputation). And customer complaints are often as much about missing or inaccurate information as the service interruptions themselves. To lessen these risks electronic information displays must be much more reliable than the system itself, and if this cannot be attained they are best removed.

Upgraded equipment is being installed across the rail network


The simplest information display systems (eg blackboard and chalk) require no special expertise to maintain. Lapses in availability (eg running out of chalk) or poor readability (due to bad writing) can be diagnosed and resolved at the local station level. The key issue here is likely to be the extent to which customer-facing staff are kept informed of short-notice service changes and disruptions.

Arrangements for managing automated real-time information are more complicated. Day to day ‘babysitting’ may be done at control desks at bus depots, operations centres or major railway stations. Faults that are beyond the control of stations and can only be fixed by centrally-deployed technically-trained personnel.

Responsibility and accountability are divided (a likelihood in any technically specialised area but accentuated through franchising) and recurring problems may be unresolved defects from two or three operators ago.

A difference between the treatment of service delivery and passenger information is that operator contracts (at least for train and tram) impose penalties for non-performance of the former each month. There is also a requirement for public reporting through ‘Track Record’ and these topics are frequently matters for media comment.

In contrast contracts specify no hard performance standards for real-time information system reliability nor the public reporting of same. While the latter is in line with other cities it does mean that (unlike service reliability) discussions of PID reliability are more anecdotal than factual.

The reliabilty of passenger information systems has a lower profile than either of the above, so is unlikely to the the topic of such special action. Nevertheless it sometimes makes the media when tested and found wanting, for instance during last Tuesday’s disruptions when it was found that the SMS alert system lacked the message sending capacity to promptly advise all subscribers.

Even if public standards existed, the extent to which a new incoming operator could or should be held liable for systems inherited from and unfixed by previous government and private operators is debatable. But in the end it boils down to contractual obligations (which the government drafts, signs, enforces and should be accountable for). Additionally the government can negotiate with the operator enhancements beyond what’s in the contract at an additional public cost (examples being the strengthening of the Comeng train air conditioners or late night services).


The fragmentation of responsibility, only limited accountability, the dependence on IT, the interconnection of various systems at multiple sites (of various origin and age) and use of wireless communication all increase the risk of failure.

Real-time passenger information systems are of only limited value unless they are much more reliable than the services they are intended to monitor and indicate.

If such systems are to be a beneficial part of the transit network (and passengers increasinly appear to want and expect it), increased attention will need to be paid to the management, procedures and technology that make the difference between information reliability and unreliability.

No comments: