Although all buses conform to current regulatory requirements, there is a need for change in bus standards as we head towards a future fleet of connected and autonomous vehicles. In addition, the Mayor of London has set a target as part of the London Transport Strategy to achieve zero road collision deaths for buses in London by 2030. In response to this challenge, Transport for London (TfL) commissioned the Transport Research Laboratory (TRL) to deliver a programme of research to develop a new Bus Safety Standard (BSS).

The BSS is a safety focused standard for vehicle design and system performance. All the research work has been centred on the amendment of TfL’s Bus Vehicle Specification, which is used in the bus contracting process. It prescribes what a London bus should look like, how it provides passenger capacity and supports user needs, meets emissions standards and a range of other engineering requirements. The BSS extends the current specification by providing performance based test and assessment procedures, to encourage vehicle design changes that will help to deliver on the vision zero targets. Our Academy Director, Richard Cuerden, discussess this approach in this video by TfL.

The Safety Measures

TRL analysed in-depth data from real world injury collisions involving buses for TfL and identified a range of countermeasures capable of both preventing future collisions and mitigating the consequences in terms of injury severity should they occur. Based on this evidence, TfL specified a number of safety measures of interest. TRL reviewed the regulations and existing bus technologies on the market for each of these safety measures. Throughout the process, TRL has worked closely with bus manufacturers and operators to understand the technical feasibility of the safety measures. This has included partnering with them to create prototype solutions, which were used in the development of the test procedures, as well as increasing the overall understanding of the effectiveness of each safety measure. The resulting procedures are outcome based, rather than specifying a particular system or supplier, so that each is future proof and supports further innovation.

The safety measures specified are as follows:

  • Driver Assist – helping the driver to avoid or mitigate the severity of incidents. This includes: Advanced Emergency Braking (AEB) systems use forward looking sensors such as LiDAR, Radar, Camera, or fusions of data from more than one sensor, to identify the risk of an imminent collision. AEB will brake only if an emergency arises and the driver is unresponsive. Already widely fitted on HGVs and cars, considerable attention has been given to modelling the balance between collision avoidance and the risk of injury to both seated and standing passengers on board. This includes consideration of preventing vulnerable road user (VRU) injuries, the casualty savings amongst passengers on board if a collision is averted, and the risk of potentially additional injuries resulting from false activations of the system. New bespoke test procedures have been developed to minimise the likelihood of trauma from a false activation of the system.  

Intelligent Speed Assistance (ISA) is based on a digital speed limit map of London. The system interprets the speed limits for the bus position and prevents the driver from accelerating above them.

Improved Direct and Indirect Vision – this involves an assessment of the area around the bus that can be seen by the driver. Improvements can be achieved by better direct (eye-line) vision through the windows, or indirect vision via the use of mirrors, or blind-spot information systems and camera monitor systems (CMS) in the future. TRL has developed an innovative approach to improving vision for bus drivers through creating a combined direct and indirect vision standard.

Pedal Application Error – a variety of measures are used to help a driver prevent or to recover from an unidentified acceleration incident, where they have pressed the accelerator pedal instead of the brake.

Runaway Bus Prevention is a system of interlocks to stop the bus from rolling away if exceptional circumstances lead to the driver forgetting to apply the parking brake when leaving the seat. Based on task analysis workshops with drivers, human factors experts at TRL have generated a new checklist to govern the system’s performance.

  • Partner Assist – helping the other road users involved to avoid the collision. For example, an Acoustic Vehicle Alerting System (AVAS) has been reviewed whereby a quiet running (e.g. electric) bus is as conspicuous as a standard diesel bus, to help pedestrians and cyclists detect its presence. In addition, visual conspicuity has been assessed to help vulnerable road users to detect the presence of a bus and the collision risk it represents before starting to cross the road. For both of these measures, TRL has developed innovative evaluation procedures in order to help identify which solutions are most effective in reducing casualties.
  • Partner protection – reducing the severity of injuries for road users outside the bus in a collision. This includes a review of the front-end design of a bus, such as impact protection, energy absorption assessment, and run over prevention measures.It also comprises the impact performance of wing mirrors and their potential replacement with a Camera Monitor System (CMS). For this measure the test procedures have involved both simulations and headform impacts on the front of buses.

  • Occupant protection – reducing the severity of injuries for people on-board the bus. This comprises an assessment of the protection provided for passengers, including a visual inspection of the interior to design out potentially injurious features and encouragement of better positioning and selection of features. Innovative research has assessed whether higher back seats may be of benefit in the event of an impact, with simulations and physical seat testing providing new evidence. However, further research is needed in this area to develop robust and practicable seat design performance standards. This measure also includes testing anti-slip flooring.

For further information on these safety measures, the executive summary from the wider research can be viewed here>

Next steps

Launched on 16th October 2018, the BSS is a shift change in the approach to safety for London’s buses. The BSS will be a rolling programme, meaning this research is only the starting point. Testing and trials will continue to investigate the capability of new technologies and bus features. The specifications will be updated regularly to extend the preventative and protective benefits of both present and future safety measures. 

To take the BSS into its next chapter, TRL has developed a roadmap to provide a guide for these future developments. The roadmap will be a key tool for bus manufacturers and operators in understanding TfL’s requirements, and will enable them to plan for the future. It will be an evolving document with regular updates to maintain relevance. Overall, it will present a ‘preferred’ date earlier than the ‘required’ date, to reflect the anticipated first to market and leaders of the technologies, and therefore to encourage the earlier adoption of safety systems.

However, there are many further safety systems that could be implemented on buses, as well as new innovations yet to come. After all, the bus industry and its supply chain are expected to offer a wide range of safety innovations in the future through the work they are doing on an on-going basis. To support this process TfL has set the bus industry an Innovation Challenge, based on a framework developed by TRL and opening in early 2019, to deliver evidence that these new innovations are effective. TRL has championed the research behind the BSS. We will continue to strive toward greater safety on buses by working with bus manufacturers and operators in developing new state-of-the-art and cost-effective solutions based on a robust evidence-led approach in line with this Innovation Challenge.

Overall, we will work to see these standards adopted by other cities and countries in order to help achieve the vision zero for buses around the world.

By Alix Edwards, Vehicle Safety & Technology Consultant for TRL

 

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