Glamorgan Inter-Valley Road The area was rural and sparsely populated until the mid 19th century, when the discovery of coal led to a major industrial boom. The geography of narrow river valleys sandwiched between mountains meant that land space was at a premium, with roads and railways running along limited land space. With relatively little sunlight reaching the valley floors, the local climate in the valleys was depressing. Visiting a town in a neighbouring valley, only a few miles away
as the crow flies, could involve a round trip. The A4061 was typical of this, and around 1900 it was a
dead end road from Bridgend to
Nantymoel, requiring a detour via the Ogwr Fach Valley and
Tonyrefail to reach the
Rhondda Valley. The downturn of the coal mining industry after
World War I hit the Rhondda particularly hard due to its isolation and lack of access, with high unemployment by the 1920s. In 1924 a series of new mountain roads, to connect isolated valleys, was proposed, including a new through route from Bridgend to Hirwaun via the Rhondda. As well as providing unemployment relief and connecting communities,
Glamorgan County Council hoped the better access to the mountain summits would provide recreation, which
Lord Temple described as "a playground for all time for those people". In addition to the A4061, the A4107 to Abergwnfi and a mountain road from
Llyn Fawr to
Maerdy in the
Rhondda Fach valley were planned as part of the same project. campaigned for the A4061 to be completed. The road schemes were designed by
Ministry of Transport engineer and surveyor George Macpherson, with a standard planned width of , with an additional on one side for pedestrians. By 1929, £356,431 (now ) had been spent on constructing of new road (including the A4107 and all connecting links). The Bwlch-y-Clawdd section opened at the end of 1928, while the Rhigos Road section, from Treherbert to Hirwaun, delayed by financial constraints, opened on 4 November 1929.
Herbert Morrison, Minister of Transport, visited the works in 1930 and was impressed by the progress and effort expended in the project. The link road from Llyn Fawr to Maerdy was never built. In 2013, a large sink hole appeared on the Rhigos Mountain Road section. The road was shut for several days for repairs. In 2016,
Rhondda Cynon Taf County Borough Council announced a £1.25 million resurfacing package for the A4061 between Treherbert and Hirwaun. The road was closed for three weeks while the council laid around 6,000 tonnes of tarmac. In August 2018, the Rhigos and Bwlch sections were both closed because of a burst water main and essential remedial works respectively. ==Landmarks==