Schedule Adherence: ITS Evaluation Guide

Schedule adherence has become a priority as passengers’ expectations of service reliability have increased. There are two types of schedule adherence: Headway and Timetable.

Headway refers to where the time interval between vehicles arriving at a stop is maintained. It is often used in high-frequency services, such as where a vehicle arrives at a stop every five minutes during the peak passenger period. Passengers do not need to know the timetables and just arrive at the stop, confident that the most they will have to wait is the headway time (e.g., five minutes in this case).

High frequency routes have many advantages for passengers and are increasingly being seen as the future of public transport in high density cities. Managing headway requires knowledge of the bus in front and has been difficult to properly achieve until the advent of today’s modern, sophisticated AVLC software.

Timetable adherence refers to keeping a vehicle to a set timetable for a route, for example, a vehicle arriving at a particular stop at 15:05. Passengers then know a vehicle will be at their stop at the planned time.

For rail services, timetable adherence is essential as track safety issues mean that access windows are very tightly controlled, and a single vehicle delay can potentially impact the entire network. Rail operations typically have very high availability rates.

Schedule adherence times (both for headway and timetabled services) are typically displayed in a control room and on a driver console. A simple colour indicator shows a driver how they are running against their target.

If they run a scheduled service, schedule adherence software shows if they are early, on time, or late compared to the planned timetable. If they are running a headway service, this is compared to targets and shows if they are too close to the service in front or if the time gap is too great. This allows the driver to adjust their speed to arrive at the planned time or maintain the service headway frequency.

Benefits

The benefits of schedule adherence software include:

Regular and reliable services. The implementation of schedule adherence systems ensures drivers are notified of their punctuality, keeping to the scheduled departure and arrival times. Service reliability improvements and on-time service increase passenger ridership.

Better passenger experience. Passengers plan their lives around which bus, train, ferry, or tram service they want to use. They don’t want to miss their service, so for less frequent services they want that service to be punctual and not leave them behind. Schedule adherence systems meet this need by ensuring that services run on time. Ideally however, passengers just want to show up at a bus stop arrive at a time that suits them and know that a service will arrive very shortly. For these high frequency services, managing services to a defined headway is more important than the schedule and enables passengers to plan their movements based on an anticipated wait time rather than catching a specific service.

Better resource allocation. Commuters do not like to board their service, only to find it overcrowded. This experience is even worse after a long wait and vehicles ‘bunch’ – causing the first service to be crowded, with subsequent services almost empty. Managing schedule adherence allows for better vehicle resource allocation and improved passenger services.

Evaluation Guide

When evaluating schedule adherence systems, these questions should be asked:

1. Does the system allow for both headway and timetable adherence?
For Bus Rapid Transit (BRT), or high-volume systems that are high frequency, headway schedule adherence makes a lot of sense. High frequency services are highly sought after by passengers[8] and is seen as the way of the future in places like Sydney and London where up to 80% of bus passengers travel on high frequency routes. For other routes, with lower frequency services such as feeder routes, timetable adherence is a more suitable solution. Make sure you choose a system that can handle both types of schedule adherence. This allows you to operate both headway and timetable services on different routes or during peak and off-peak times.

2. Does the system update the driver regularly, so they know they are ahead or behind schedule?
The best schedule adherence systems continually update the driver visually with colour indicators and timers. The system will notify them how long they must wait at stops and allows them to easily adjust their speed and driving style to keep on time. When managing to headways the system should tell the driver if they are too close or too far away from the bus in front, allowing them to slow down or not delay so as to maintain the target gap.

3. Does the system automatically notify a control centre operator if there is a deviation from the schedule or route?
Good schedule adherence systems send automatic notifications to a control centre operator if a vehicle leaves a stop early or is ahead or behind schedule beyond a set time value. This allows for timely intervention by the control centre. Interventions can significantly reduce disruptions and improve service reliability.

4. Do you need a network overview?
Most schedule adherence systems have a network overview diagram where status and overall route performance are viewed easily. Operators can examine high-level information for the network before viewing detailed performance metrics of individual routes. This allows the control centre to focus on underperforming services to bring vehicles back on time.

5. Do you require the ability to manage the whole route view?
Practical schedule adherence systems can help control centre staff visualise route performance. They offer visualisations like line and ladder diagrams that can be stretched and zoomed in/out so controllers can focus on specific locations that may be problematic. These systems usually allow control centre staff to assign certain routes to individual workstations. This allows each staff member to only focus on a single route or a selection of routes; and allows for efficient resource allocation.

6. Can control centre staff quickly identify a vehicles’ schedule status?
Most schedule adherence systems have a visual system where vehicle representations change colour based on their schedule adherence. A vehicle ahead of schedule can be red, on schedule can be green, while a vehicle behind schedule is blue. These visual cues quickly allow control centre staff to identify where they need to spend their time and attention. Not only are schedule variation colours based on time ranges (i.e., -1 to +2 minutes is on time), but colours are also customisable to reflect the operators’ preferences. Once defined, these colours should be reflected throughout the system on all the graphical views so that operators understand the situation at a glance and do not have to adapt to each view.

7. Is the visual schedule indication consistent in the control centre and the vehicle?
If the driver and the service controller have a consistent and synchronised indication of timetable adherence or headway operations, they can work together to manage service delivery.

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