Just one of six Norfolk schools picked for trials banning traffic from nearby roads at pick-up and drop-off time is still running the experimental scheme.
Sites in Norwich, Costessey and Wymondham were selected by Norfolk County Council for trials of the 'School Streets' scheme earlier this year.
The idea of the 18-month experiment was to bring in timed road closures around schools, with certain streets shut to vehicles during the school run, so children could travel more safely and sustainably.
But a shortage of volunteers to help with road closures has seen two of the schemes "paused" - and three more never started.
The initiative began in three schools - Dussindale Primary on the edge of Norwich, along with Robert Kett Primary and Browick Road Primary and Nursery in Wymondham.
But of those, only Robert Kett is still running the scheme, with the other two pausing the initiative due to struggles to find volunteers to supervise road closures.
A proposed trial at St Augustine's Catholic Primary in Costessey was scrapped after a feasibility study.
And, what the council described as "significant changes in the senior leadership team" at Wensum Junior and Nelson Infant meant those schools did not take part.
At a recent council meeting, Maxine Webb, Labour county councillor for Norwich's Wensum ward, said she hoped solutions could be found to enable schemes to go ahead.
Robert Savage, Conservative councillor for Wymondham, said there had been "mixed success", with the Robert Kett scheme going well, but a shortage of volunteers hindering the Browick Road trial.
A report will come before councillors in March before decisions are made on the future of the initiative.
A council spokesperson said: "The pilot has seen a lot of support from residents and parents, and has already provided some very useful feedback, although one thing we’ve found, so far, is that it can be difficult to secure sufficient numbers of local volunteers needed to supervise the road closure points and enable the scheme to operate at each school.
"A report on School Streets will be considered by councillors in March, so they are able to review all the findings from the work here in Norfolk, and consider what the next steps should be."
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