The £600million transformation of New Street Station offers a golden opportunity to expand Birmingham city centre beyond the inner ring road.

Development of Southside, based on redevelopment of the wholesale markets site at Digbeth, offers the chance to build a new district where office, retail, residential, cultural and entertainment uses would coexist.

The Big City Plan envisages “repairing the street structure” to make the area more welcoming and easier to move through.

It speaks of “huge potential” to improve the built environment to the south of the historic city core, beginning with the redevelopment of New Street.

The document notes: “The redevelopment of the wholesale markets site will provide the opportunity to remove barriers to movement, create new open spaces and open up routes to the area from Park Central, Eastside, Digbeth and Highgate.

“One possibility is to create a sizeable city square, “Moat Square”, together with a lake or major water feature, on the site of the mediaeval moated manor house to draw people down from the Bullring and into southside.”

Planners suggest this would further the theme of Birmingham as a water city, with the centre of activity concentrated on New Street Station, Hurst Street and Moat Square.

Several options for the development of Southside are proposed. These include a major new office quarter near New Street Station and a natural expansion of the central shopping area. It’s suggested Moat Square could become an attraction on the scale and quality of Victoria Square and would become a “magnet” for people using the city centre by hosting a wide range of activities from open air events to markets, theatres and cafes.

Alternatively, Southside could be developed as food quarter with markets and specialist shops or a theatre and entertainment district to complement the existing Hippodrome, Electric Cinema and Birmingham Royal Ballet.

A large square would be created on the wholesale markets site, large enough to stage major outdoor events, making this a focus for a much enlarged leisure and theatre sector, with close links to the Hippodrome and Gay Village.

Finally, the Big City Plan suggests that Southside could become a focus for a cluster of tall buildings on the wholesale markets site.

Another area designated for city centre expansion is Westside, taking in land between Broad Street, Bath Row and the Middleway outer ring road.

Options include developing Westside as a specialist shopping area, focusing on the canal, the Mailbox, The Cube and the area around Bridge Street and the National Indoor Arena.

Another idea has Broad Street becoming a “major entertainment boulevard” with much more commercial leisure development being encouraged with larger scale buildings, wide pavements and “vibrant advertising” to create a “brash and buzzy” character.

It is also suggested that Suffolk Street Queensway, between the bottom of Broad Street and Holloway Circus, could be transformed into a pedestrian-friendly tree-lined avenue surrounded by tall buildings.

The document adds: “The Broad Street area is an important focus for Westside. Although it developed an entertainment function in the 1990s, its role in the future may be more akin to the local high street, with shops and services for the growing residential and business communities around it.”

n The Work in Progress conference, which will look at the Big City Plan proposals, will take place at the International Convention Centre on Tuesday.