• Bus Safety Standard

The research work is centred on the amendment of TfL’s Bus Vehicle Specification, which is currently used in the bus contracting process. This specification sets out many aspects of what a London bus should look like, how it should provide passenger capacity and support passenger’s needs, meet emissions standards and a host of other engineering requirements. The new research will develop this to provide a greater emphasis on the safety performance of the bus.

How will safety improvements be assessed?

TfL has specified 13 safety measures of interest and these form the basis of the research. For each measure, a thorough review of the current regulations and standards and a review of the current bus fleet and available supplier solutions has been conducted.

Trials are currently being conducted and these have two purposes: firstly to evaluate the solutions in a realistic environment in order to ensure that a safety improvement is actually feasible; and secondly to inform the development of an independent test and assessment protocol. The exact evaluation methods depend upon each of the 13 measures being developed and are tailored to suit each one. The ratings developed will be simple pass/fail and/or a more complex performance rating; again, tailored to suit the nature of each safety measure. Injury and collision data will be used to derive the scenarios and/or injury mechanisms to be addressed; as such it will be an independent, performance-based assessment.

As an illustration of the range of approaches being used, for Automated Emergency Braking (AEB) evaluation, we will include track testing and on-road driving, whereas for crashworthiness protection of Vulnerable Road Users (VRUs) we will use computer simulation. The engineering aspects are being accompanied by human factors assessments. For example, visual and acoustic conspicuity measures (that aim to help VRUs better identify the path and speed of approaching buses) will be assessed by a representative population of VRUs. High risk, but thankfully rare, events such as runaway buses and pedal confusion will be assessed using prototype vehicles and a representative sample of London bus drivers. 

As a minimum, each technology will need to demonstrate significant improvement in safety performance against the baseline in controlled testing for scenarios that are representative of real service. However, translating this into an assessment of casualty reduction is challenging. Many of the measures do not exist yet in the bus market, so a predictive analysis will be undertaken if necessary. This will predict the numbers and severities of casualties prevented, and look at how well each technology can reduce them.

Competing technologies will not be tested or rated against each other; only one technology or vehicle will be used for each trial. Of course, it is possible that TfL will want to carry out comparative testing in the future to assess technologies/ vehicles against the newly developed BSS tests, but that is not within the scope of the current project.

What elements form part of the research?

The results of the trials will feed into the new BSS that will be incorporated into bus operator contracts from the end of 2018, however It’s unlikely that all 13 measures will be included in the 2018 requirements. A business case will be developed for each safety measure based on an economic valuation of the predicted casualty reduction. This will be balanced against the costs of adding the feature into the specification and any other operational costs or benefits. The key output for the research is the amended and extended Bus Vehicle Specification for TfL to use in the bus contracting process. These revisions will be additionally peer-reviewed by independent safety experts external to TRL too. Accompanying the specification there will be guidance notes to help inform the bus operators and manufacturers of what the specification is aiming to achieve and some practical tips on how to meet the requirements.

A road map has been developed by TRL to provide a guide for future developments of the BSS, and this is currently out for consultation with the bus industry. This road map will become a key tool for bus manufacturers and operators in understanding TfL’s requirements, and will be a rolling document with regular updates so as to remain relevant. The timescales will be challenging but realistic. Euro NCAP’s road map for passenger car safety has been used as the model for our approach.

Similarly, Euro NCAP is being used as a model to inform the development of an overall safety rating system. This will allow operators and TfL to select the buses with highest safety ratings when balanced against their other economic and operational concerns.

The Euro NCAP Advanced Reward system is another approach that will be used to help develop a framework for assessing other safety features that are not currently part of the 13 measures of the BSS. After all, the bus industry and its supply chain can offer a vast range of safety improvements and these should be given some form of independent assessment and recognition reward if they are deemed worthy. Applicants will need to provide a dossier of evidence describing a safety system and its effectiveness, so that an independent panel of safety experts can assess it. 

The challenge

Ultimately, the goal of the research is to develop an independent standard and framework for assessing the safety of TfL’s buses. Bringing all the safety measures together and ensuring that they are working in a complementary manner is complex. The programme has a tight schedule and is promising to deliver some novel research into new areas of bus safety. Strong steps towards safer buses for London are achievable through this Bus Safety Standard, which we would hope will grow in subsequent years to become a world-leading benchmark for bus safety. 

Published in Thinking cities 

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