He died on 18 October 1947 and was cremated at Mt Thompson Crematorium. He was survived by his wife and five daughters.
Professor Hawken was involved in the founding of IEAust in 1919 and was its president in 1923 and a councillor till his death. At his suggestion in 1928, Queensland became the first state to legislate for compulsory registration of consulting engineers.
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. He graduated M.C.E. 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 eminent English engineer, E. H. Salmon, who had written an authoritative text on the subject. 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.
Professor Hawken was reserved but excessively formal, with a wry, sometimes biting sense of humour. Engineering and the University was his life. He saw the complete engineer as a combination of wide experience and wide culture, encouraged originality in his students, called himself the 'senior student' and was known as 'hanks'.
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. He was involved in many major Brisbane projects including an early Victoria Bridge (the abutment is still standing near QPAC) and the Story Bridge. In 2006, Brisbane City Council proposed Hawken Bridge as one of 5 names for a new green bridge linking the University of Queensland to Dutton Park but ended up choosing the name Eleanor Schonell Bridge.
In May 1947, he was asked to participate in an inquiry into a railway crash at Camp Mountain.
Named in his honour
Two major engineering buildings and library at the University of Queensland have been named in his honour. The first Hawken building was built in about 1964  However it was vacated by the Engineering Faculty after the construction of a new building in about the 1990s. The name Hawken Building was then assigned to the new building, and the old Hawken Building was renamed the Prentice Building, reflecting the Prentice Computer Centre which took over the building.
The annual Hawken address, presented by the Queensland division of IEAust, is usually held in its Hawken Auditorium, the main lecture theatre in the Hawken Building.
- Australian Dictionary of Biography
- Newington College Register of Past Students 1863-1998 (Syd, 1999) pp85
- Alumni Sydneienses
- "Family Notices.". The Courier-Mail (Brisbane, Qld. : 1933-1954) (Brisbane, Qld.: National Library of Australia). 20 October 1947. p. 10. Retrieved 6 March 2011.
- "JUDGE MANSFIELD TO HEAD INQUIRY INTO RAILWAY SMASH.". Morning Bulletin (Rockhampton, Qld. : 1878-1954) (Rockhampton, Qld.: National Library of Australia). 9 May 1947. p. 1. Retrieved 6 March 2011.
- Photo of construction of Hawken Building, accessed 6 March 2011.
- Photo of the first Hawken Building, retrieved 6 March 2011.
- "Rename drive to honour professor.". The Courier-Mail (Brisbane, Qld. : 1933-1954) (Brisbane, Qld.: National Library of Australia). 15 January 1949. p. 4. Retrieved 6 March 2011.
- D. H. Trollope, Hawken, Roger William Hercules (1878 - 1947), Australian Dictionary of Biography, Volume 9, MUP, 1983, pp 230–231.