Urban freeway means the principal arterial that provides the higher levels of mobility, safety and efficiency in the movement of high-volumes of traffic at high speeds in the big city. However, most of the urban freeways don't play their roles in the mobility, safety and efficiency because they experience the severe transportation problems by the incoming or outgoing traffic on the urban freeway ramp junctions regardless of the peak periods. Thus, the purpose of this study is to investigate and analyze the speed characteristics on the urban freeway ramp junctions, construct and verify the speed conversion models, and finally clarify the relationship between the mean speeds on the urban freeway ramp junctions in the big city.
From the results of the speed characteristic analyses, construction and verification for the speed conversion models on the urban freeway ramp junctions under the study, the following conclusions were drawn；
ⅰ) The on-ramp flow was shown to exceed the capacity, but the off-ramp flow was shown to be under the capacity during the peak periods,
ⅱ) The on-ramp speed showed a big difference during the time periods, but the off-ramp speed didn't show a big difference regardless of the time periods,
ⅲ) Speed conversion factors(, ) in the Yule & Kendall's model were proved to be almost consistent with those of the integrated model on the ramp junctions of urban freeway. However, they were proved to be completely different from the speed conversion factors(, ) in the on-ramp and off-ramp models on the ramp junctions of urban freeway, respectively,
ⅳ) Speed conversion factors(, ) in the Yule & Kendall's model were also proved to be completely different from the speed conversion factors(, ) under the stable and unstable conditions on the ramp junctions of urban freeway, respectively, and
ⅴ) The speed conversion models were proved to be definitely classified by the ramp types(on-ramp and off-ramp) and the flow conditions(stable and unstable conditions) for a higher explanatory power in the model construction.