In a city that is continuously experiencing rapid growth and increase in population, the
importance of an efficient transport system cannot be stressed enough. Transport serves
among other functions accessibility and movement of people and goods from one point or part
of a city to the other. In cities and towns in the developing world, (Nairobi included) the transport
system has not been able to effectively carry out these roles due to traffic congestion as
manifested by increased travel time due to traffic jams. This study therefore assessed a typical
urban road in the city of Nairobi and set to find out the effects of informal commercial activities
on the road reserve on the efficiency of the transport system. Taking Juja road as the case, the
study was carried out in Mathare, Bondeni, area between the Moi airbase and the junction of
Juja road and Eastleigh 1st avenue. It focused on the causes of inefficiency in the transport
system with particular emphasis to the effects of roadside commercial activities. The actives
here included those that were located on the road reserve and whose client base was mainly
the pedestrians. Data for the study was collected from two main sources, literature review and
actual site visits to the study area. Secondary data was obtained from both published and
unpublished materials, library and internet research. Primary data obtained from the field was
captured by photography, distribution of questionnaires to key respondents, interviews and
observation among other methods and analyzed by the use of quantitative and qualitative data
analysis methods including SPSS and the output presented in the form of graphs and pie
charts. Findings from the study indicate that the efficiency of the transport system is reduced by
the bad driving habits of road users particularly operators of public service vehicles. The
efficiency is also hindered by the sharing of the carriageway by motor vehicles and non
motorized forms of transport (particularly cyclists and handcart pushers) including pedestrians
which increases the risk of accidents occurring on the road. Sharing of the road was mainly due
to the high levels of obstruction and reduction of the road space by the informal activities on the
road reserve. The study finally recommends that for the efficiency of the transport system to be
improved, there would be need to plan for separation of motorized from the non motorized
transport by the creation of separate pedestrian infrastructure and the taming of bad driving
habits by PSVs operators. There is also the need to plan for the informal roadside activities to
reduce interference on the flow of traffic.