Eng. Wambua was determined to become an engineer from an early age gaining inspiration from a particularly dreadful stretch of road near the Lake Victoria, his home place. The road would become impassable when it rained and vehicles would get stuck for days. This was when the engineer in him paused the question, ‘How to do you make roads’.
Determined to become a civil engineer, Wambua completed his lower A level course he was forced to study overseas universities since there was no institution offering it in the country by then. In 1962 he was accepted at the Budapest Technical University in Hungary and went on to study for six years.
Though several Africans had started on the course, only Wambua and a fellow student from Ghana managed to complete the rigorous syllabus. On his final year in Budapest he was recruited to join the Ministry of Transport and Communication where within an year he was appointed the deputy resident engineer in Eldoret-Kapsabet road.
In 1968,he started working with the Ministry of Works where he first worked closely with a team of experts from the British Road Research Laboratory in UK on traffic engineering matters. After a while he was attached to consulting engineers Howard Humphreys and Partners.They mainly worked on design and site supervision .He later went back to headquarters to understudy an expatriate Norwegian in Roads Department.
His background was heavily oriented towards roads.Wambua was sent to England to take a course in transportation planning at the University of Sussex. After two years at Sussex, he participated in a course on Transportation at the Economic Development Institute of the World Bank in Washington.
His basic experience covered planning design construction and maintenance of roads and bridges. In addition, he prepared several feasibility study reports and also participated in the negotiation of loans and grants for roads and bridges with different lending agencies.
By late 1971 and 1974, Wambua had been promoted to superintending engineer and senior superintending engineer (planning) respectively. He became Chief Executive Engineer in 1978 and by 1979 he was promoted to Chief Engineer (roads and aerodromes).
In October 1983, Wambua became the second civil engineer to take up a top civil service post in the Ministry of Transport and Communication after the retirement of Eng. Simon Mbugua. Wambua who believed that engineers could make good administrators without wasting their engineering education was once a registrar in the Engineers Registration Board.