Free flow 和 optimum density 有联系吗?

kirin

例如在underwod模型中,要用到ko,即optimum density.
如果利用underwood来求不同路段(即有不同free flow speed的路段)的速度.
是否可以假设采用相同的optimum density?
这个问题困扰我好长时间了.
因为我发现free flow speed 和optimum density 没有直接联系.
那么underwood模型的实用性不是很差?

zhxo

[这个贴子最后由zhxo在 2005/03/05 06:44pm 第 4 次编辑]

The author want to know whether it is poosible to presume the same critical
density(as fas as im concerned ,the critical density seems to be used by a majority of transortation study individuals) in the different Underwood traffic models, which means that different road has dffferent free flow speed. My viewpoints on this problem are discussed below.

Generally, it is impossible to adopt the same critical density in the different Underwood stretches models because there are two decisive parameters in the Underwood model:free flow speed and jam density.And, the critical density could be generally deduced through this two parameters.In addtition, so do the other last century static models. So,generally presuming the same citical density fails to develop this traffic models.

However,there are exceptions by chance; the different free flow speed correspond the two same critcal density. It is just a specific phenomenon.

Last by not least, the reseach area should be advisably palced on the newly
realsed traffic models,such as there phase traffic theory, because several
recent detected characters cannot be fully explained by the fundamental diagram,which is the theory basis of the classic, frequently used and imprecisely traffic models.
best whishes!!