Are there any (a) building restrictions or (b) legal constraints preventing the contractors from continuing the work on the M1/Grayston Drive pedestrian and cyclist structural bridge in Johannesburg, Gauteng; if not, (i) why has work on the bridge halted, (ii) why has the inquiry into the collapse of the specified bridge been delayed until March 2017, (iii) who gave the instructions for the specified inquiry to be delayed for so long and (iv) why could the expert not appear before inquiry in the next few weeks to answer the new set of questions and allow the enquiry to continue?