The Shrewsbury Big Town Plan, which would involve several large changes to the town centre including a riverside plaza, proposes to have a "multimodal transport hub".
A study was undertaken earlier in the year by transport planners and designers, PJA, with a planning consultation expected to follow.
However, campaign group Bus Users Shropshire say the idea of using the railway station forecourt for buses as proposed is impractical.
The group say that foremost among their concerns is the small size of the station forecourt, which "can be thronged" with arriving train passengers which could constitute a safety hazard in the presence of buses.
The train station building, Bus Users Shropshire say, is an important landmark and should be a welcoming place of arrival for pedestrians. They also raise concerns over the possibility of making use of Cross Street for a one way bus operation. The bridge height restriction of 3.3m is lower than the typical height of battery electric buses which will replace diesel buses in coming years.
The proposal to move the bus station onto the railway station site would also require a line of bus stops and shelters along Castle Foregate under the railway bridge.
Les Lumsdon from Bus Users Shropshire said: "The rationale for the Big Town Plan is for Shrewsbury to become a better, more attractive place to visit. Pushing bus passengers onto dark and damp, pigeon-infested streets is the exact opposite of what we need to do to entice residents and visitors onto the enhanced bus services our council says it wants.
"The council should be asking their consultants to come up with a Movement Strategy that makes best use of the existing bus station site for multimodal operations. Instead, they’ve made it clear they want to sell the bus station for redevelopment to fix a hole in their budget, shoehorning future bus operations onto inappropriate locations in and around the railway station. We want integration, but not if it is substandard."
One of the most contentious issues around the Big Town Plan when a major consultation was held at the start of last year was that the bus station could be scrapped.
Councillor Ed Potter, Shropshire Council’s former representative on the Shrewsbury Big Town Plan Partnership, said previously: “Getting movement of people right is absolutely vital to Shrewsbury’s future, and follows on from the Masterplan Vision which generated so much useful discussion and debate last year.
“The movement and public realm strategy will relate to lots of important work already in progress, such as the Local Transport Plan, the High Street weekend low traffic trial, planned transformation of the town’s Park and Ride, and of course the Riverside development.
“As this work progresses, we’ll be looking to get people involved and seek their views and what’s important to them in lots of different ways.
“This will be an holistic and integrated plan for the whole town - which is why the Shrewsbury Big Town Plan Partnership leading this work is important - all partners working together for the greater good of the town.”
Shropshire Council has been contacted for a comment.