NAIROBI, Kenya Aug 29- Commuters and motorists along Ngong Road have been left stranded after matatu operators staged a protest over what they termed as continued harassment by police officers.The protest, which began at dawn, saw dozens of matatus parked on both sides of the road near the Ngong Road- Prestige Plaza junction, effectively blocking one of the city’s key transport arteries.The operators are demanding a meeting with senior officials from the National Transport and Safety Authority and the police traffic department to address their grievances.Meanwhile, traffic officers on the ground struggled to redirect vehicles and ease the congestion. Motorists are urged to use alternative routes including Argwings Kodhek and Riara Road until further notice.