Abstract: Alone with fast urbanization in world, traffic control
became a big issue in urban construction. Having an efficient and
reliable traffic control system is crucial to macro-traffic control.
Traffic signal is used to manage conflicting requirement by allocating
different sets of mutually compatible traffic movement during distinct
time interval. Many approaches have been made proposed to solve
this discrete stochastic problem. Recognizing the need to minimize
right-of-way impacts while efficiently handling the anticipated high
traffic volumes, the proposed alternative system gives effective
design. This model allows for increased traffic capacity and reduces
delays by eliminating a step in maneuvering through the freeway
interchange. The concept proposed in this paper involves
construction of bridges and ramps at intersection of four roads to
control the vehicular congestion and to prevent traffic breakdown.
Abstract: An efficient freeway system will be essential to the
development of Africa, and interchanges are a key to that efficiency.
Around the world, many interchanges between freeways and surface
streets, called service interchanges, are of the diamond configuration,
and interchanges using roundabouts or loop ramps are also popular.
However, many diamond interchanges have serious operational
problems, interchanges with roundabouts fail at high demand levels,
and loops use lots of expensive land. Newer service interchange
designs provide other options. The most popular new interchange
design in the US at the moment is the double crossover diamond
(DCD), also known as the diverging diamond. The DCD has
enormous potential, but also has several significant limitations.
The objectives of this paper are to review new service interchange
options and to highlight some of the main features of those
alternatives. The paper tests four conventional and seven
unconventional designs using seven measures related to efficiency,
cost, and safety.
The results show that there is no superior design in all measures
investigated. The DCD is better than most designs tested on most
measures examined. However, the DCD was only superior to all
other designs for bridge width. The DCD performed relatively poorly
for capacity and for serving pedestrians. Based on the results, African
freeway designers are encouraged to investigate the full range of
alternatives that could work at the spot of interest. Diamonds and
DCDs have their niches, but some of the other designs investigated
could be optimum at some spots.