[6][7] Hawken's academic bent was evident by 1903 in a remarkably advanced paper to the Sydney University Engineering Society on the structural analysis of bridges.

Hawken worked as an engineer in the Federated Malay States for four years and then with local government authorities in New South Wales.

from Sydney in 1918 after submitting a thesis on column design, a frontier topic of the period, and appears to have had slightly the better of a lively argument with the English engineer, E. H. Salmon, who had written an authoritative text on the subject.

[8] In the 1920s, he turned again to earth pressures and the stability of slopes; he thus was one of the pioneers of the study of soil mechanics, a subject generally neglected until the 1950s.

In later work on rainfall runoff and flooding potential and the economic appraisal of engineering schemes, his ideas were well ahead of his time.

[6] His work included design of an early version of the Sydney Harbour Bridge that did not proceed to construction, and identification of crossing points for the Brisbane River.