Acoustic Vehicle Alerting System (AVAS) Retrofit Project

The Mayor’s Transport Strategy (MTS) sets out the Vision Zero goal of zero people killed or seriously injured (KSIs) on London’s roads by 2041. It includes targets for a 70% reduction in KSIs by 2021 and for no one to be killed on or by a bus by 2030. The Bus Safety Standard (BSS) was launched in 2018 to help achieve the Vision Zero goal for buses. The BSS mandates the use of safer vehicles and supports safer behaviours and speeds, specifying safety requirements that new buses entering service in London must meet. An Acoustic Vehicle Alerting System (AVAS) is one of a number of the measures in the BSS. AVAS is a system to make quiet running buses (i.e. electric, hybrid or hydrogen) audible to pedestrians and cyclists, and other road users outside the vehicle. The United Nations Economic Commission of Europe (UNECE) Regulation 138 has required AVAS on new electric and hybrid vehicles since July 2021. TfL committed to introducing this early and since September 2019 AVAS has been required on all new quiet running London bus models as part of the BSS. The UNECE regulatory requirements have also been exceeded for London Buses. This includes the development of a unique Urban Bus Sound, which along with moving the speakers to the front of the bus, aims to maximise the benefits of AVAS by making it easier for Vulnerable Road Users (VRUs) to distinguish the sound over typical city background noise and improve acoustic conspicuity compared to a diesel bus. A 'beacon' element has also been introduced which provides directionality to blind and vision-impaired persons (or anyone listening for the bus but not looking). In addition, a responsive AVAS system has more recently been developed. Responsive AVAS will provide optimal volume levels for the sound dependent on the location of the bus. This will both optimise the potential effectiveness for casualty reduction but also minimise the impact on the London soundscape, and the possibility of complaints. However, the requirement for new buses in London to have AVAS does not address existing or pre-2019 manufactured buses in the fleet. Therefore, to support our Vision Zero targets for no deaths on or by a bus by 2030 and for zero deaths or serious injury by 2041, we are developing a project to potentially retrofit AVAS onto existing quiet running buses in London (i.e. electric, hybrid or hydrogen buses). This retrofit will be of responsive and non-responsive AVAS, the type of AVAS chosen being determined in each instance by the model of bus being fitted, and whether that model is capable of supporting responsive AVAS or not.