3 research outputs found
Performance assessment of signalised intersection using uav videography : a case study of the jorissen-bertha street intersection in Johannesburg
Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2023.Intersections are critical sections of a road network as they are designed to accommodate
various conflicting movements. For signalised intersections with pre-timed controls in urban
areas, it is essential to assess the performance of the signal timing plans at regular intervals.
The objective of this study is to develop a method that could be employed to assess the
performance of any signalised intersection using a typical intersection in Johannesburg as the
case study. The method relies on video data gathering using Unmanned Aerial Vehicle, from
which various traffic parameters such as the approach flow rate, saturation flow rate,
headways and delays are measured. The performance of the intersection is assessed by
comparing observed delays with theoretical delays computed using HCM delay models. The
study showed that UAV video data can be processed relatively easily to measure various
traffic flow parameters required to assess the performance of signalised intersections
Mechanistic response of conventional vs perpetual flexible pavements under similar loading condition : a 3-d finite element analysis
Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2023.A 3D finite element analysis was conducted on several models of conventional and
perpetual pavements to assess the similarities and differences in their structural and
fatigue response when both pavement types are subjected to varied axle load and wheel
configurations. The models were designed as a five-layer pavement system made up of an
asphalt surface laid on an asphalt binder course. The base used was a graded crushed
stone of G1 quality. Asphalt materials were assumed to be viscoelastic, while the granular
base, subbase and subgrade were assumed to be linearly elastic. All material properties
conformed to the South African Mechanistic Design Method (SAMDM) Guideline. Tandem
axle dual wheel loading produces the least safety factor and fatigue life, and the highest
damage among other configurations. Perpetual pavement models from the same materials
were found to be more structurally rigid when comparing strains and damage in the long
term. They show more resistance to distress by traffic loading when compared to
conventional pavements. It was concluded that a 3-Dimensional Finite Element Analysis
(FEA) is a suitable tool for supporting Mechanistic-Empirical design methods and provides
a platform for further investigation of the behaviour of perpetual pavements
Travel time reliability assessment of public transport : a case study of the Johannesburg bus rapid transit (brt) corridors
Papers presented virtually at the 41st International Southern African Transport Conference on 10-13 July 2043Travel time reliability is one of the key measures of transport network performance. It also
provides an indication of the level of predictability of travel time from origin to destination
for any mode of transport. This paper presents an investigation of the travel time reliability
of the Bus Rapid Transit system in Johannesburg - the Rea Vaya Bus service. The study
method involves field collection of travel time information through onboard surveys along
the BRT corridors. Travel time reliability is measured using a set of indicators proposed by
the Federal Highway Administration (FHWA) of the US Department of Transportation.
Among the objectives of the study is to gain some insight into the critical operational and
road network factors that impact travel time for both peak and off-peak periods. Some of
the factors considered include commuter boarding and alighting delays, stop frequency
and delays at intersections. From the study, one of the notable factors found to currently
affect travel time reliability for the BRT system was additional delays from traffic signal
disruption due to the ongoing load-shedding scheme implemented by the national power
agency, ESKOM