20 Nov 2025 Lisa Marie Bowen · Prevention of Future Deaths report Surrey
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Concerns raised 5 Failure of anti-locking braking systems to reliably recognise tyre detachment View source Lack of regulatory requirements for under-run protection device strength View source Lack of industry testing and data collection on braking following tyre detachment View source Insufficient strength of under-run protection devices View source Failure of anti-locking braking regulations to specify requirements for tyre detachment View source See 2 more concerns
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AI-generated summary
Lisa Marie Bowen · Prevention of Future Deaths report
This summary was generated using AI from the published report. Please read the original report for the complete account.
Report summary
Lisa Marie Bowen died instantaneously from fatal injuries after her Toyota Corolla’s tyre detached while she was driving on the M25, and the vehicle failed to stop before colliding with a stationary lorry. The principal concerns were that the anti-locking braking system substantially reduced braking after tyre detachment, and that the lorry’s under-run protection device was insufficiently strong to prevent or reduce the under-run. The report also raised concerns about the adequacy of relevant testing, regulations and protection requirements.
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× Source evidence
How this individual concern was interpreted PFD Monitor created a concise, searchable interpretation from the report wording shown below. The report was sent to Toyota (GB) PLC; that does not assign responsibility.
PFD Monitor interpretation Failure of anti-locking braking systems to reliably recognise tyre detachment
Wider context from the report “Concern 1
As stated above, the brakes on the Deceased’s Toyota Corolla did not work effectively because, when the brake pedal was pressed, the vehicle’s anti-locking braking system was activated, and it operated to reduce the braking effect almost entirely. At the inquest I heard evidence that:
(i) Following the tyre detachment, the speed of the wheel with a detached tyre was much higher than the speed of the three other wheels with undamaged tyres.
(ii) The anti-locking braking system recognised this differential in speed, but perceived that the problem lay with the three slower wheels and assumed that they had locked or were at risk of doing so.
(iii) Consequently, each time the brake was applied, the anti-locking braking system immediately released the braking pressure to the three slower wheels in order to avoid them locking, thereby prioritising the preservation stability and steerability over braking.
(iv) In this way, the anti-locking braking system was working in accordance with its design.
(v) The system was unable to recognise that the problem in fact lay with the fourth wheel which was rotating much more quickly than the other wheels because its tyre had detached.
(vi) The outcome was an unintended effect of the system’s design which arose because the specific scenario, of tyre detachment occurring whilst the vehicle was being driven, which was thought to be a rare occurrence, had not been taken into account in the design process.
(vii) Testing of anti-locking braking systems and braking performance, following a tyre detachment, is not undertaken by the industry as a whole and, therefore, relevant data is not collated.
At the inquest and PFD hearing I was informed that –
(i) A large number Toyota Corolla motor cars continue to be driven on the roads of the UK with the same anti-locking braking system as was in Ms Bowen’s vehicle.
(ii) Anti-locking braking systems are developed by a small number of specialist companies and it may well be that other vehicles currently on the roads of the UK have systems similar to that in Ms Bowen’s car.
(iii) The company which developed the anti-locking braking system used in Ms Bowen’s car (Advics) has since developed and improved its system so that it is better able to recognise if one wheel speed is so different from the others that the data from that wheel should be ignored as unreliable. However, the improvements are not foolproof , not least because acceleration or deceleration of the vehicle affects this function.
(iv) The anti-locking braking system now used in Toyota Corolla motor cars has been developed by a different company (Bosch) and it is not known by Toyota precisely how it would respond following a tyre detachment whilst the vehicle is being driven .
(v) It seems that relevant regulations concerning anti-locking braking systems do not address or specify requirements relating to the scenario faced by Ms Bowen.
Although the detachment of a tyre whilst a vehicle is being driven is thought to be a rare occurrence, I am concerned that that may not be the case and that if it were to happen again, in the same or similar circumstances, the risk of future death continues.
” Open source report × Source evidence
How this individual concern was interpreted PFD Monitor created a concise, searchable interpretation from the report wording shown below. The report was sent to Toyota (GB) PLC; that does not assign responsibility.
PFD Monitor interpretation Lack of regulatory requirements for under-run protection device strength
Wider context from the report “Concern 2
This concern relates to the catastrophic failure of the under-run protection bar (“the Device”) that was in place on the piece of the lorry with which Ms Bowen collided. At the inquest I heard and accepted expert evidence which established that:
(i) The Device was compliant with all relevant regulations and legal requirements, save only that fixing bolts of an incorrect strength had been used to attach it to the lorry’s chassis.
(ii) The strength of the Device was grossly insufficient, either to have prevented any underrun, or even to have reduced the extent of the Toyota’s under-run.
(iii) The Device would not have been strong enough to do so even if the correct fixing bolts had been used.
One expert stated that he was aware that some under-run protection devices are capable of providing protection against much greater forces than is currently required under the law and he expressed disappointment that the relevant legislation and regulations are not more robustly framed, so as to require the use of these much stronger devices.
I am concerned that, in the absence of more stringent requirements in relation to the degree of force that an under-run protection device should be capable of withstanding , a risk of future death arises.
” Open source report × Source evidence
How this individual concern was interpreted PFD Monitor created a concise, searchable interpretation from the report wording shown below. The report was sent to Toyota (GB) PLC; that does not assign responsibility.
PFD Monitor interpretation Lack of industry testing and data collection on braking following tyre detachment
Wider context from the report “Concern 1
As stated above, the brakes on the Deceased’s Toyota Corolla did not work effectively because, when the brake pedal was pressed, the vehicle’s anti-locking braking system was activated, and it operated to reduce the braking effect almost entirely. At the inquest I heard evidence that:
(i) Following the tyre detachment, the speed of the wheel with a detached tyre was much higher than the speed of the three other wheels with undamaged tyres.
(ii) The anti-locking braking system recognised this differential in speed, but perceived that the problem lay with the three slower wheels and assumed that they had locked or were at risk of doing so.
(iii) Consequently, each time the brake was applied, the anti-locking braking system immediately released the braking pressure to the three slower wheels in order to avoid them locking, thereby prioritising the preservation stability and steerability over braking.
(iv) In this way, the anti-locking braking system was working in accordance with its design.
(v) The system was unable to recognise that the problem in fact lay with the fourth wheel which was rotating much more quickly than the other wheels because its tyre had detached.
(vi) The outcome was an unintended effect of the system’s design which arose because the specific scenario, of tyre detachment occurring whilst the vehicle was being driven, which was thought to be a rare occurrence, had not been taken into account in the design process.
(vii) Testing of anti-locking braking systems and braking performance, following a tyre detachment, is not undertaken by the industry as a whole and, therefore, relevant data is not collated .
At the inquest and PFD hearing I was informed that –
(i) A large number Toyota Corolla motor cars continue to be driven on the roads of the UK with the same anti-locking braking system as was in Ms Bowen’s vehicle.
(ii) Anti-locking braking systems are developed by a small number of specialist companies and it may well be that other vehicles currently on the roads of the UK have systems similar to that in Ms Bowen’s car.
(iii) The company which developed the anti-locking braking system used in Ms Bowen’s car (Advics) has since developed and improved its system so that it is better able to recognise if one wheel speed is so different from the others that the data from that wheel should be ignored as unreliable. However, the improvements are not foolproof, not least because acceleration or deceleration of the vehicle affects this function.
(iv) The anti-locking braking system now used in Toyota Corolla motor cars has been developed by a different company (Bosch) and it is not known by Toyota precisely how it would respond following a tyre detachment whilst the vehicle is being driven.
(v) It seems that relevant regulations concerning anti-locking braking systems do not address or specify requirements relating to the scenario faced by Ms Bowen.
Although the detachment of a tyre whilst a vehicle is being driven is thought to be a rare occurrence, I am concerned that that may not be the case and that if it were to happen again, in the same or similar circumstances, the risk of future death continues.
” Open source report × Source evidence
How this individual concern was interpreted PFD Monitor created a concise, searchable interpretation from the report wording shown below. The report was sent to Toyota (GB) PLC; that does not assign responsibility.
PFD Monitor interpretation Insufficient strength of under-run protection devices
Wider context from the report “Concern 2
This concern relates to the catastrophic failure of the under-run protection bar (“the Device”) that was in place on the piece of the lorry with which Ms Bowen collided. At the inquest I heard and accepted expert evidence which established that:
(i) The Device was compliant with all relevant regulations and legal requirements, save only that fixing bolts of an incorrect strength had been used to attach it to the lorry’s chassis.
(ii) The strength of the Device was grossly insufficient, either to have prevented any underrun, or even to have reduced the extent of the Toyota’s under-run.
(iii) The Device would not have been strong enough to do so even if the correct fixing bolts had been used.
One expert stated that he was aware that some under-run protection devices are capable of providing protection against much greater forces than is currently required under the law and he expressed disappointment that the relevant legislation and regulations are not more robustly framed, so as to require the use of these much stronger devices.
I am concerned that, in the absence of more stringent requirements in relation to the degree of force that an under-run protection device should be capable of withstanding, a risk of future death arises.
” Open source report × Source evidence
How this individual concern was interpreted PFD Monitor created a concise, searchable interpretation from the report wording shown below. The report was sent to Toyota (GB) PLC; that does not assign responsibility.
PFD Monitor interpretation Failure of anti-locking braking regulations to specify requirements for tyre detachment
Wider context from the report “Concern 1
As stated above, the brakes on the Deceased’s Toyota Corolla did not work effectively because, when the brake pedal was pressed, the vehicle’s anti-locking braking system was activated, and it operated to reduce the braking effect almost entirely. At the inquest I heard evidence that:
(i) Following the tyre detachment, the speed of the wheel with a detached tyre was much higher than the speed of the three other wheels with undamaged tyres.
(ii) The anti-locking braking system recognised this differential in speed, but perceived that the problem lay with the three slower wheels and assumed that they had locked or were at risk of doing so.
(iii) Consequently, each time the brake was applied, the anti-locking braking system immediately released the braking pressure to the three slower wheels in order to avoid them locking, thereby prioritising the preservation stability and steerability over braking.
(iv) In this way, the anti-locking braking system was working in accordance with its design.
(v) The system was unable to recognise that the problem in fact lay with the fourth wheel which was rotating much more quickly than the other wheels because its tyre had detached.
(vi) The outcome was an unintended effect of the system’s design which arose because the specific scenario, of tyre detachment occurring whilst the vehicle was being driven, which was thought to be a rare occurrence, had not been taken into account in the design process.
(vii) Testing of anti-locking braking systems and braking performance, following a tyre detachment, is not undertaken by the industry as a whole and, therefore, relevant data is not collated.
At the inquest and PFD hearing I was informed that –
(i) A large number Toyota Corolla motor cars continue to be driven on the roads of the UK with the same anti-locking braking system as was in Ms Bowen’s vehicle.
(ii) Anti-locking braking systems are developed by a small number of specialist companies and it may well be that other vehicles currently on the roads of the UK have systems similar to that in Ms Bowen’s car.
(iii) The company which developed the anti-locking braking system used in Ms Bowen’s car (Advics) has since developed and improved its system so that it is better able to recognise if one wheel speed is so different from the others that the data from that wheel should be ignored as unreliable. However, the improvements are not foolproof, not least because acceleration or deceleration of the vehicle affects this function.
(iv) The anti-locking braking system now used in Toyota Corolla motor cars has been developed by a different company (Bosch) and it is not known by Toyota precisely how it would respond following a tyre detachment whilst the vehicle is being driven.
(v) It seems that relevant regulations concerning anti-locking braking systems do not address or specify requirements relating to the scenario faced by Ms Bowen .
Although the detachment of a tyre whilst a vehicle is being driven is thought to be a rare occurrence, I am concerned that that may not be the case and that if it were to happen again, in the same or similar circumstances, the risk of future death continues.
” Open source report
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Source evidence
How this respondent action was interpreted
PFD Monitor created a concise, searchable interpretation from the published response wording shown below.
PFD Monitor interpretation Continue regularly reviewing ABS design with specialist suppliers to identify appropriate safety updates.
Verbatim wording from the response “As in all areas of car design changes, Toyota is committed to the continued evolution of ABS. The design is therefore regularly reviewed and, if appropriate, updated in conjunction with specialist suppliers, with changes gradually introduced starting from new models. Although total tyre detachment (as in this incident) is very rare, some of the ABS design changes already implemented can help detect tyre detachment while driving.” Source location Response from Toyota GB PLC
Open published response
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Source evidence
How this respondent action was interpreted
PFD Monitor created a concise, searchable interpretation from the published response wording shown below.
PFD Monitor interpretation Implement ABS design changes that can help detect tyre detachment while driving.
Verbatim wording from the response “As in all areas of car design changes, Toyota is committed to the continued evolution of ABS. The design is therefore regularly reviewed and, if appropriate, updated in conjunction with specialist suppliers, with changes gradually introduced starting from new models. Although total tyre detachment (as in this incident) is very rare, some of the ABS design changes already implemented can help detect tyre detachment while driving.” Source location Response from Toyota GB PLC
Open published response
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Source evidence
How this respondent position was interpreted
PFD Monitor created a concise, searchable interpretation from the published response wording shown below.
PFD Monitor interpretation Total tyre detachment is highly unusual and rare, with only one known case affecting ABS performance and producing a fatal outcome.
Verbatim wording from the response “The total detachment of a tyre from a wheel of a passenger vehicle is highly unusual. You heard evidence from an expert automotive engineering consultant who described the specific scenario that preceded this collision – namely total tyre detachment - as “very unusual and rare”. This is consistent with Toyota’s experience.” Source location Response from Toyota GB PLC
Open published response
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Source evidence
How this respondent position was interpreted
PFD Monitor created a concise, searchable interpretation from the published response wording shown below.
PFD Monitor interpretation Accurate detection of complete tyre detachment is not currently technologically possible, and no industry solution yet exists.
Verbatim wording from the response “The experts at the inquest agreed that, unfortunately, the technology does not yet exist to detect accurately when a tyre has completely detached from a car. According to one of those experts, work is being done to understand how anti-lock braking systems could be designed to detect complete tyre detachment – but no one in the industry yet has the answer.” Source location Response from Toyota GB PLC
Open published response
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Information checked against published PFD reports and official responses · Data reviewed 7 Sep 2026 · About data quality and limitations