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PDF (DX094490.pdf) - White Rose Etheses Online

PDF (DX094490.pdf) - White Rose Etheses Online

214 CHAPTER 7

214 CHAPTER 7 CONCLUSIONS

215 A computer simulation model has been developed to study the performance of entries to roundabouts. It allowed the comparison of straight and flared entries and the study of, the effect of turning movements, flow characteristics, and the gap acceptance parameters on delay and capacity associated with such entries. Further, the abstraction of gap-acceptance parameters from data collected at roundabouts was examined and a method for such abstraction was proposed. 1. Several methods for estimating the gap-acceptance parameters were tested. It was concluded that a model which fits a single line to the accepted gaps only, predicts adequately both the critical gap and the move-up time. 2. The predictions of capacity by the computer sim- ulation model were compared with observed values. That gap- acceptance parameter values used as input to the model were abstracted from the observed data. While the agreement was not exact, it was though to be sufficient and the predictions did not exhibit consistent overestimation or underestimation. 3. The concept of the effective number of lanes was used as a measure of the increase in capacity associated with the conversion of a two-lane entry from straight to flared. It was found that the effective number of lanes is a function of the circulating flow and, secondarily, of the critical gap. The full use of the extra lanes provided by flaring, is only achieved at very high circulating flows. A value of 50% increase in capacity has been achieved by all studied conditions for a circulating flow of 2300 veh/hr approximately. 4. Reduction to delay associated with conversion from straight to flared entries is on average 40% or more for

The Archaeology of Medieval Europe - White Rose Research Online
See PDF version here. - Blue & White Online
See PDF version here. - Blue & White Online
See PDF version here. - Blue & White Online
See PDF version here - Blue & White Online
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PDF (267549_VOL2.pdf) - White Rose Etheses Online
PDF (388061_vol2.pdf) - White Rose Etheses Online