Abstract:
A speed breaker is a rounded hump surface across the roadway which is provided to slow
down the vehicles. Speed breakers are employed primarily at the locations where vehicles
interact with vulnerable road user’s i.e. pedestrians in bulk volume. Furthermore, to prevent
accidents resulting from over speeding of vehicles, speed-breakers are employed at some
locations along the roadway. However, accidents may occur regardless of presence or
absence of speed-breakers. Improper use of speed breaker might act as a catalyst for causing
accidents. The purpose of this study is to determine the variation in speed for different
vehicles at a speed breaker located along New market to Azimpur road section at Dhaka.
To observe the variation of speed along the speed-breaker, we considered an 80 ft. road
segment keeping the speed-beaker at middle. This approach will allow us to observe how
drivers decelerate before approaching to the speed breaker and accelerates leaving the speed
breaker. Since we did not have the access to speed gun, we used indirect method to calculate
the instantaneous speed of vehicles. For this, we further subdivided the 80 segment into 5
small segments and marked them at the field and recorded the video using smartphone to
calculate the time required for vehicles to cross those segments. Analysis shows that the
behavior of driver for bus, car and rickshaw are not same at the speed breaker. On an
average, bus drivers reduced their speed from 13.16 km/hr to 8.12 km/hr while reaching at the hump of speed breaker, afterwards they increased their speed from 8.12 km/hr to 10.61
km/hr while leaving the speed breaker. On the other hand, car driver’s speed before the
speed breaker hump, at the speed breaker hump and after the hump were observed to be
17.55 km/hr, 11.6 km/hr and 15.23 km/hr respectively. Whereas rickshaw drivers speed for
those threes case was observed 10.97 km/hr, 8.11 km/hr and 8.88 km/hr respectively.
Therefore, it can be said that the low speed vehicle’s speed reduction rate is lower than the
fast moving vehicles.
