Mr Rigby said part of the bus station area could be pedestrianised, because there were fewer buses using the station, and a section of its interior space would become a retail area for start-up businesses.
The guard who was killed was standing outside the checkpoint, while the two wounded guards "were standing in a more protected area, " said Interior Minister Muammer Guler said.
Shahzad has a Karachi identification card, a sign of Pakistani residency, and his family is from volatile northwestern Pakistan, where government forces have been fighting Taliban militants who have strongholds in the area, according to Pakistani Interior Minister Rehman Malik.