Network Rail is extending Glasgow's Queen Street station to accommodate longer platforms, and it will be connected to an expanded Buchanan Galleries shopping centre, with new car park and access walkways on different levels.
Strathclyde Partnership for Transport has written to Network Rail seeking assurances on a number of issues that occur when connecting the station with other modes of travel throughout the city.
They are concerned about Fastlink, bus connections with Central station, access for disabled passengers, the impact on Buchanan Street bus station and the Maryhill suburban train line to Anniesland station.
Network Rail is currently consulting on the station works, which include the demolition of SPT headquarters Consort House, in West George Street, and part of the Millennium Hotel.
SPT said it recognised the opportunity to improve a key gateway into Glasgow and the west of Scotland, but stated: "The redevelopment is likely to have significant impacts on the wider transport network during the proposed development period and beyond."
In a report to SPT councillors to be considered this week, Eric Stewart, assistant chief executive and Gordon Maclennan, chief executive of SPT, outlined the potential concerns. Platform work will be carried out one at a time, reducing capacity from seven to six, with fears the Maryhill service could be reduced as a result.
The report said: "SPT will seek assurance that the proposal to lengthen High Level platforms will not result in any diminution of suburban rail services such as Maryhill.
"SPT will continue to press for Maryhill services to be included in the EGIP programme."
The work on Queen Street station is expected to start later this year and last five years, with completion by 2019.