Shropshire Council had intended to bring in the temporary measure in a bid to combat pollution, but now says it needs more time to weigh up the benefits and potential impacts of the scheme.
The postponement means the council could miss out on grant money that had been secured for the trial.
The right-hand lane closure was intended to reduce the amount of traffic pollution reaching nearby properties, and was set to be the first intervention trialled as part of a plan to cut overall nitrogen dioxide levels in the Shrewsbury Air Quality Management Area to below legal limits.
A report setting out plans to improve air quality in both Shrewsbury and Bridgnorth – was due to be presented to Shropshire Council’s health and wellbeing board on at a meeting on Thursday.
But Councillor Dean Carroll, board chairman and cabinet member for public health, said he wanted to see more work done to investigate the proposed measures.
He said: “There are some suggested proposals made in the report that we feel actually need further consultation and engagement with stakeholders and with internal colleagues as to how they have a knock-on impact on other plans and policies of the council.
“I’m specifically referring to a proposed trial lane closure in Shrewsbury, which I think we need very careful consideration of, particularly alongside our Highways colleagues and the Big Town Plan.
“I think it’s right that we take all of that on board first before we ask health and wellbeing board to endorse that as an approach.”
Members agreed to defer consideration of the report to a future meeting.
Councillor Cecilia Motley, portfolio holder for transport, said: “I think that’s a very sensible approach, because I think we need to take a holistic view of this situation.
“If we try and do it in bite sized chunks and we don’t knit it up together I think we may find that we have gaps, so I think we need to do a bit more work on this.”
Councillor Carroll said: “The amount of grant funding in question here is relatively minimal and it is more important that we get these decisions right after thorough deliberation rather than rush ahead.”
The legal maximum for nitrogen dioxide concentration is 40 microgrammes per cubic metre of air.
This is currently being exceeded by around 30.5 per cent in the Shrewsbury AQMA and 17.5 per cent in Bridgnorth.