With regard to her reply to question 2495 on 14 July 2015, what (a) empirical evidence was used by her department to come to the conclusions stated in the reply, more specifically that (i) the overall economic impact was positive, (ii) delays on the road network has decreased, (iii) traffic growth of more than 20% in many instances could be accommodated and (iv) the development that took place in the immediate vicinity of upgraded interchanges such as Lynnwood, Atterbury, Garsfontein, John Vorster, Allandale, etcetera reflects the positive impact the road improvement project had on Gauteng and (b) economic studies is her department referring to in the specified reply when she indicates that the Friday, 31 July 2015 977 INTERNAL QUESTION PAPER: NATIONAL ASSEMBLY NO 26 - 2015 project renders a high return on investment and a B:C ratio of 8 to 1?