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The iBus system – serving as the backbone for London’s bus network

Posted: 30 April 2009 | Simon Reed, iBus Project Director, TfL | No comments yet

The transformation of the London bus network in recent years is a great public transport success story. Over the last decade, bus patronage in London has increased by 53%. Every weekday, over 8,000 buses run on almost 700 routes, carrying 6.4 million passengers and well over 2 billion trips are made on London’s buses annually – more than on the London Underground and the entire UK rail networks combined.

As the bus network has grown, so have the demands placed upon it. Passenger expectations have risen – today’s London bus passenger demands reliable, accessible services and effective journey information. The previous London bus radio communications and vehicle location system, designed for a much smaller bus fleet, could not cope with the continued development and expansion of the network – a new system was needed that provided more effective monitoring of bus services and better radio communication with drivers.

The transformation of the London bus network in recent years is a great public transport success story. Over the last decade, bus patronage in London has increased by 53%. Every weekday, over 8,000 buses run on almost 700 routes, carrying 6.4 million passengers and well over 2 billion trips are made on London's buses annually - more than on the London Underground and the entire UK rail networks combined.As the bus network has grown, so have the demands placed upon it. Passenger expectations have risen - today's London bus passenger demands reliable, accessible services and effective journey information. The previous London bus radio communications and vehicle location system, designed for a much smaller bus fleet, could not cope with the continued development and expansion of the network - a new system was needed that provided more effective monitoring of bus services and better radio communication with drivers.

The transformation of the London bus network in recent years is a great public transport success story. Over the last decade, bus patronage in London has increased by 53%. Every weekday, over 8,000 buses run on almost 700 routes, carrying 6.4 million passengers and well over 2 billion trips are made on London’s buses annually – more than on the London Underground and the entire UK rail networks combined.

As the bus network has grown, so have the demands placed upon it. Passenger expectations have risen – today’s London bus passenger demands reliable, accessible services and effective journey information. The previous London bus radio communications and vehicle location system, designed for a much smaller bus fleet, could not cope with the continued development and expansion of the network – a new system was needed that provided more effective monitoring of bus services and better radio communication with drivers.

iBus, one of the world’s largest integrated vehicle location and passenger information systems, was introduced in response to these challenges. Delivering better radio communications for drivers, real-time journey information for passengers and accurate bus service monitoring for controllers, iBus is revolutionising how bus services are delivered in London.

Passenger information

From a passenger’s viewpoint, a key benefit of iBus is real-time journey information. Onboard audio announcements and visual displays inform passengers of the route number of the bus, its final destination and the name of the next stop. Passengers, particularly tourists and people travelling in an unfamiliar part of town, can find their way around more easily. On a network of the size and complexity of London’s, providing passengers with clear, concise information is of vital importance.

In addition to automated announcements, iBus enhances drivers’ ability to communicate with passengers, providing them with a tannoy system and a range of pre-recorded announcements for use in situations they regularly encounter. For example, when the bus is crowded, drivers can use a pre-recorded announcement to ask passengers to move down inside the bus.

Some of the people to benefit most from iBus are those with visual or hearing impairments, or learning disabilities. London Buses already boasts the most accessible fleet in the UK for disabled passengers. The entire fleet comprises low-floor, wheelchair accessible vehicles, with the exception of a small number of classic Routemasters running on two heritage routes. iBus continues to enhance the accessibility of London’s buses, opening up the bus network to an even wider cross section of London’s population. It has been welcomed by the Guide Dogs for the Blind Association, which has reported an increase in the uptake of mobility training on London’s buses among its members since the introduction of iBus.

It’s not only on board that iBus is improving the quality of information provided to passengers. The waiting times displayed on Countdown signs, installed at around 2,000 of London’s 19,000 bus stops, are now more accurate. Before the introduction of iBus, these estimates were calculated using roadside beacons which registered the position of the bus and estimated its arrival time based on the time the preceding three buses took to reach the stop. iBus is considerably more sensitive and flexible, no longer relying on beacons but taking into account more factors to identify the location of buses and providing more frequent updates of their progress.

Enhanced radio

Despite its considerable benefits to passengers, improved passenger information was not the primary reason for the development of iBus. One of the key factors was the need for better radio communications across the bus network. In the early 1980s, the London bus fleet was half its current size and relied on a Band III radio system for communication between drivers and service controllers. Following significant expansion of the bus network, the old radio system had come to the end of its useful life and needed to be replaced. This coincided with the government’s withdrawal of Band III licences to free up spectrum for digital broadcasting, requiring London’s bus radios to switch to the mid-Band spectrum. London Buses chose to use this as an opportunity to redesign its bus radio system.

The iBus radio system is designed to cater for the growing needs of London’s bus network with scope for expansion beyond the current fleet size. As well as increased resilience, wider coverage and better quality radio communications, iBus offers service controllers the ability to choose to speak to their entire garage fleet, individual drivers, or specific groups of drivers in one area or on one route.

iBus’ combination of improved radio and automatic vehicle location comes into its own when a driver needs to report an incident on the network. CentreComm, London Buses’ control centre, handles up to 1,200 calls from bus drivers every day, covering everything from cars parked in bus lanes to major traffic incidents. Previously, 40% of the duration of the average call was consumed by identifying the location of the bus. Now this information is immediately displayed for the CentreComm staff on an on-screen London street map. Calls can be dealt with more efficiently and, where necessary, emergency services and/or London Buses staff can be on the scene faster.

CentreComm is able to talk to individual drivers or broadcast a message to groups of drivers. iBus also allows CentreComm staff to send messages to passengers via the on-board signs and broadcast over the PA system to bus passengers in the event of a major service issue or other emergency.

Service control and performance

Through the data it provides to Service Controllers, iBus is also helping to deliver a more reliable bus service.

Bus services in London are contracted to private operating companies. Rather than merely paying operators by the number of bus kilometres covered, contracts are designed to incentivise them to run a reliable service, with a two year extension to the contract automatically available if specific performance targets are met. In order for this system to work effectively, London Buses needs accurate data on the performance of individual operators and routes. iBus is a valuable addition to the tools London Buses has at its disposal to monitor performance, providing detailed running time reports that compare the actual running of buses against the schedule. This information provides an accurate picture of reliability, and a good indication of the performance of specific routes and operators.

The operators themselves are also benefitting from the sophisticated journey information provided by iBus. The system has been installed in 58 service control centres at bus garages, providing controllers with a live representation of where buses on a particular route are at any one time, and whether they are ahead or behind schedule, or running to time. The improved radio communications offered by iBus mean that messages can be quickly and accurately relayed to bus drivers if they are not on schedule, enabling them to take corrective action.

Logistics and challenges

iBus has to be much more than a Global Positioning System (GPS) for buses. Traditional GPS has limitations, especially in large cities such as London, where satellite signals can be affected by surrounding buildings – known as multipath and urban canyon effects. What makes iBus unique is the enhanced navigation algorithm it uses to generate information on the location of each vehicle.

The navigation algorithm uses four sources of information in addition to conventional GPS to identify the location of a bus. Firstly, an on-board odometer provides a measure of the distance the bus has travelled from the last stop. Secondly, known points the bus has passed are matched to the route – each bus stop is a known point, and when a bus opens and closes its doors this is recorded. Thirdly, on-board gyroscopes record corners turned by the vehicle. Finally, iBus checks the bus’ position against the route it should be following. The inputs from each of these measurements are combined and from this the iBus software calculates the bus’ position on the road. Across the network, tests have confirmed that there is a 95% confidence of the bus being within +/- 12m of its reported position, with the mean figure being closer to +/- 3m.

Once the iBus system had been developed and tested, the next logistical challenge was installing it on London’s 8,200 buses. Buses were fitted at a peak rate of 28 per day over an 18 month period at one of two installation centres in London or by a roving team which fitted buses in situ at garages. The aim during the installation was that no bus should be out of service for more than a day – some considerable challenge given the vast range of bus makes and models that make up the London fleet, each of which demanded a slightly modified installation process. Meticulous planning saw that the installation centres were aware well in advance of exactly what bus specifications to expect on any given day, and this information was combined with some hi-tech warehousing to ensure that 97% of buses were fitted out successfully and back in service the next day.

Developing the ‘data’ for the iBus system presented a further logistical challenge. The system was required to provide precise information across 700 routes and 19,000 bus stops, each of which was subject to a full audit to ensure that the actual stop on the ground and the stop name and location on the iBus system matched. Once the data had been checked and validated, a voice artist, Emma Hignett, was recruited to record each of the route numbers and stop locations for audio announcements. Emma began recording bus stop names at the end of May 2006 and completed them in summer 2007.

The success of iBus was continually monitored and assessed as the roll out progressed and adjustments and changes to the system were made based on this feedback. The volume of announcements was one issue that required careful attention to ensure they could be heard over background noise, whilst not being uncomfortably loud in quieter conditions. Following careful analysis of the different types of bus and levels of background noise encountered, levels have now been set that are acceptable for the vast majority of passengers. However the constant renewal of the London bus fleet and the introduction of new bus types, such as hybrids with quieter engines, will mean that work to refine the system is ongoing.

The future

The roll out of iBus was completed in April 2009 and will serve as the backbone of London’s bus network for the foreseeable future. London Buses is already assessing how to use the information generated by iBus, with plans for the future including the provision of predicted bus arrival times via the internet, mobile phones and a new generation of Countdown signs for its passengers.

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