Volunteers were asked to act as traffic wardens at Tilbury Pioneer Academy in Essex in September 2015.
But the BBC can reveal the powers were enforced by just one parent, with no penalty imposed.
Thurrock Council defended the project, saying it highlighted the "deterrent value of the project".
The pilot was introduced after the council said it only had six full-time traffic wardens to police illegal parking outside its 50 schools.
However, a Freedom of Information (FoI) request by the BBC showed it was halted after three months
A lone parent volunteer enforced the rules and no tickets were issued, the FoI showed.
A spokeswoman for Thurrock Council said the trial would not be rolled out across the borough.
She said: "There has been considerable improvement in parking behaviour as a result of the scheme but, due to the significant training commitment for the volunteers, continuing the project will be difficult."
Jerry Glazier, national executive member of the National Union of Teachers in Essex, said the scheme had "the right motivation, but the wrong approach".
"In the cold light of day the practicalities were such that this was simply not an effective runner," he said.
"There needs to be proper engagement with parents."

Plans were approved for Coastal Oil and Gas Limited to drill in a field at St Nicholas.
The permit does not allow the company to carry out fracking - hydraulic fracturing of the land - to extract any oil or gas.
Fracking is subject to a temporary ban in Wales until decision-making powers on the practice are devolved.
Natural Resources Wales said it had carried out a "thorough assessment" of the company's plans before approving them, with all work including reinstatement of the land to be completed within 12 months.
"It's important that any activity of this kind doesn't harm the environment, and this permit makes it clear what Coastal Oil and Gas Limited will need to do to comply with this," a spokesman said.
"Once the work begins, our officers will regulate and monitor the site to ensure it complies with the conditions of the permit, to protect people and the environment."
The permit for exploratory drilling comes despite a moratorium on fracking in Wales pending devolution of responsibility for such decisions.
In August, the UK government urged councils in England to speed up the process of approval for fracking projects.
However, Natural Resources Minister Carl Sargeant said fracking technology was "unproven", and that Welsh Labour ministers preferred to look at renewable energy.

Two were picked up by a coastguard helicopter high up on the 3,196ft (974 metre) Munro.
Lomond Mountain Rescue Team located two others on the lower slopes.
Mountain weather forecasters were predicting winds of up to 80mph with frequent snow showers at summit level in western Scotland for Wednesday.
Not a single fine was issued during a £5,000 trial to get teachers and parents to police roads outside a primary school, it has emerged.
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Permission has been given for exploratory drilling for oil and gas in the Vale of Glamorgan.
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Four hillwalkers who got into difficulties during severe weather on Ben Lomond have been rescued.