Taxonomy and description

The basic definition of a bus fleet management system is that it is a system which facilitates the efficient management and scheduling of bus routes to ensure that buses run as per the schedule. Management of the bus fleet involves the timely arrival and dispatch of buses throughout its journey and the ability to predict and react to changing circumstances which may disrupt this, e.g. vehicle breakdowns or heavy congestion. This in turn improves the operational performance of the bus which helps: 1) improve the perception of the bus in the eyes of the travelling public and; 2) reduce the financial costs of operating services. The former can be realised by improving journey reliability and minimising the wait and in-vehicle time when travelling by bus. The latter will result from being able to better to utilise bus fleets and by reducing maintenance and operating costs (less idling and better driving styles).

The key requirement of a bus fleet management system is the ability to locate a vehicles location throughout its journey, the ability to transmit this information back to a base office and then the ability to process this data usefully to ensure you make effective use of your fleet. Increasingly the information on vehicle location is being fed to various other systems to provide better Urban Transport Control (UTC), bus vehicle priority (including intelligent bus priority) and real time information both pre-journey (at the bus stop, on the web, via SMS) and during the journey (in-vehicle). These other functions themselves can help contribute to better fleet vehicle management and whilst not considered directly by this report, are important ‘side effects' that should be borne in mind.

The majority of bus fleet management systems are somewhat limited in the amount of dynamic rerouting they can carry out during normal operations. That is because they have pre-defined routes and bus stops which must be adhered to. This contrasts with road freight HGV systems which possess the ability to reroute vehicles during operations to provide additional pick-ups or to avoid traffic congestions. There are however a small minority of more specialised bus services where operational rerouting is possible and we briefly outline them below.

• One of the latest developments to arise from bus fleet management systems is the ability to provide Demand Responsive Transport (DRT). This complements fixed route buses, with DRT services dynamically adjusting themselves to the needs of the travelling public. No vehicle will run unless someone wishes to travel, and the vehicles will detour as necessary to combine a number of trip requirements onto a single vehicle. These services are managed from a central Travel Dispatch Centre, which takes the bookings and uses a sophisticated computer system to optimise the allocation of people to vehicles. At the moment DRT is not a mainstream application but is begging to grow in popularity in rural/semi rural areas, e.g. Cornwall .

• In the US bus fleet management systems are increasing being used to optimise routes and schedules for school bus transportation services to reflect changes in where school children live.

• Airport shuttle buses in some large airports need to serve numerous docking bays spread over large areas, e.g. Dusseldorf has 74 docking bays over 723 km 2 . The time pressure inherent in airport set-ups make providing a consistent and responsive service very challenging. Bus fleet management systems have been useful in optimising fleet scheduling and providing an effective two way communication between driver and base to ensure that the fleet is responsive.

There are several technologies that allow automatic vehicle location (AVL), which are outlined below:

1. Vehicle loop – this involves detector loops cut into the road surface that interact with a transponder (tag) on a vehicle. The loops receive information from the transponder about the vehicle and pass in to a central processing unit back at base.
2. Roadside beacon – similar function to the detector loops;
3. Global Positioning System (GPS) – This uses a passive device (such as a radio receiver) located on a vehicle. This reads signals from up to 12 satellites (but needs a minimum of 3) and calculates a vehicle's surface position to within 10 to 20 metres or 1 to 5 metres if differential GPS is used

The first two types of technologies are all dependent upon equipment fixed into roadside locations. They are therefore relatively inflexible and require relocation or new equipment to be installed if the network changes etc… There has therefore been a move towards GPS technology. This removes the need to roadside based equipment and provides flexible systems that are less expensive to expand geographically. The type of detection provided by GPS can be differentiated between passive and active. The former only notifies the base station of a vehicle presence in a pre-specified location, whilst the latter provides constant information about vehicle location.

Data transmission systems are generally dictated by the type of vehicle location technology used. If the system is transponder based there is a short wireless communication between the vehicle and the detector and then generally a wireline based communication to the bus depot (plus whoever else requires it, e.g. UTC). GPS systems will communicate to the depot and other offices using a wireless system such as General Pack Radio Systems (GPRS) and Private Mobile Systems (PMS).

Unlike with freight fleet management the data flow tends to be from the vehicle the base office. In part this appears to be because there is no need for such a flow of information since the bus route cannot be changed to avoid congestion as may be the case with a HGV. If the base office wishes to communicate with its drivers then separate radio or cell phone systems are put in place. The potential flow of data from the vehicle to the base office is outlined below:

• Vehicle location at calibrated intervals or upon request;
• Vehicle location when entering a pre-specified area(virtual fence placed around a destination to inform a depot of a vehicles imminent arrival);
• Vehicle location when panic alarm triggered;
• Vehicle and driver identification;
• Fuel consumption – trip/totals;
• Driving style – speed/revs/idling/braking;
• Timed trip data – start, stops, average speed, distance;
• Driving hours; and,
• Engine performance – e.g. temperatures.

As outlined earlier this data might be simultaneously transferred to not only the bus fleet's central control room but also to a traffic signal controller (to provide bus priority) or to a central UTC computer if an area wide strategy such as SCOOT is being used.