The death of an autistic woman hit by a lorry on the A1 was an "avoidable tragedy", an inquest has heard.
Colette McCulloch, 35, died in the early hours of 28 July 2016, while a voluntary patient at Pathway House in Wyboston, Bedfordshire.
The care home should have kept her safe but failed her, assistant coroner Martin Oldham said.
Pathway House said it had changed its "joint working processes" to "prevent an event like this happening again".
Ms McCulloch was described in a 2014 clinical assessment as "a high functioning autistic young lady of talent with complex health issues".
Mr Oldham, who recorded a narrative conclusion at Central Bedfordshire Coroners' Court, said: "She was failed by a lack of a mental health assessment and by an inadequate regime of care.
"Regrettably there is no direct causal connection which enables me to return a conclusion of neglect.
"Colette died as a result of failures for which no person directly is at fault nor any single or combination of organisations.
"This causes me considerable distress."
Mr Oldham noted that Ms McCulloch was vulnerable and incapable of keeping herself safe.
When anxious she turned to alcohol and this was a factor on the night she died but "no-one will ever know how she came to be on the A1".
"Her death was an avoidable tragedy," he said.
On the day before she died, she went to see her GP but did not return to Pathway House.
She was hit by a lorry driven by Pavel Fokt and a toxicology report later revealed her blood alcohol levels were above 300mg. The legal limit for driving is 80mg.
A Pathway House spokesman said: "Our priority at all times is the wellbeing, safety and health of the people we support.
"We conducted an in-depth internal investigation and by working closely with our local authority and health service partners we have changed our joint working processes to prevent an event like this happening again."
East London NHS Foundation Trust added: "Internal and independent investigations were held to understand how and where the NHS and other agencies failed to provide Colette with the care and support she needed.
"We have listened, learned and made changes to improve how we provide services as a result of this tragic incident."