Question: When did construction start on the sydney harbour bridge?

context: No context provided
question: When did construction officially start on the sydney harbour bridge?
short_answers: 28 July 1923
context: Arch construction itself began on 26 October 1928. The southern end of the bridge was worked on ahead of the northern end, to detect any errors and to help with alignment. The cranes would "creep" along the arches as they were constructed, eventually meeting up in the middle. In less than two years, on Tuesday, 19 August 1930, the two halves of the arch touched for the first time. Workers riveted both top and bottom sections of the arch together, and the arch became self-supporting, allowing the support cables to be removed. On 20 August 1930 the joining of the arches was celebrated by flying the flags of Australia and the United Kingdom from the jibs of the creeper cranes.
question: When did construction of the Arch start on the sydney harbour bridge?
short_answers: 26 October 1928

Answer: While construction officially started on the Sydney Harbour Bridge on 28 July 1923, construction of the arch on the bridge didn't begin until 26 October 1928. Work on the bridge itself commenced with the construction of approaches and approach spans.