The Bold Street Bridge was rebuilt as a single span without any intermediate support piers, and other bridges similar to the destroyed bridge had their piers reinforced. The original inquiry into the accident found that the primary cause of the crash was "the very unsatisfactory condition of the permanent way", being the poor fastening of the track, which has caused the track to spread and allowed the left front wheel of the locomotive to come off the rail. Other contributing factors determined during investigation included the structure of the bridge itself, the condition of the track, and the condition of the locomotive. When built, the base of the Bold Street Bridge had been found to be one metre lower than the road surface at each adjoining street. In order to bring the bridge road surface up to the same height as the street concrete was added on top to remove the difference. This addition added almost triple the weight of the originally designed bridge, a factor which contributed significantly to the destruction of the wooden train carriages. It was found that the track immediately prior to the curve leading into the area of Bold Street Bridge had not been maintained correctly, leading to the locomotives' wheels to push the track out of gauge, which led the front right-hand wheel to leave the track, effectively derailing the locomotive. Locomotive 4620 had been involved in a similar accident twelve years earlier, when it had derailed at Wentworth Falls in the Blue Mountains when operating a freight service. 4620 jumped the tracks as it entered the loop at the western end (country side) of Wentworth Falls platform, resulting in the entire train derailing. The cause was found to be an irregular operation of the train brake pipe. After being recovered from this accident, 4620 had the dents and scratches repaired and placed back into service. The carriages involved were wooden bodied Supplementary Interurban Passenger Carriages, which had been converted from Country Passenger Stock by the PTC to Interurban Passenger stock. This was done by removing the previous internal arrangement of individual compartments and making the carriages an open plan similar to how passenger stock is today. This left the cars with only the side and end walls supporting the roof instead of a number of internal walls bearing the weight of the roof. It is entirely possible that if the cars had been left as built, with individual compartments, then whilst the collapse of the bridge would have crushed the carriages, the internal walls could have prevented the cars from being completely destroyed, enabling passenger to survive in pockets rather than simply being crushed. The disaster prompted substantial increases in rail-maintenance expenditure, which had been experiencing a steady decline since the Second World War due to the reduction available of materials, finances, and labour forces. The
Public Transport Commission of NSW after the accident immediately began a systematic overhaul of track maintenance in order to prevent another incident from occurring. The train driver, Edward Olencewicz, was exonerated by the inquiry due to the exhaustive investigation into the incident. Due to the Granville rail disaster and the number of victims who suffered from
crush syndrome (a little understood medical condition at the time), a number of changes were made as to how crush injuries are dealt with by rescue personnel, not only at incidents such as this, but also for smaller rescues as well. On 4 May 2017, New South Wales Premier
Gladys Berejiklian apologised to the victims of the disaster, in Parliament House after extensive pushing for the apology.
Memorial Families and friends of the victims and survivors gather with surviving members of the rescue crews annually. The ceremony ends with the throwing of 84 roses on to the tracks to mark the number of passengers killed. The original group, known as 'the trust', made submissions on rail safety issues, including recommending that fines for safety breaches be dedicated to rail safety improvements, and campaigning for the establishment of an independent railway safety
ombudsman. ==Media==