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yanyueliu / Cell_Transmission_Model_Python

A cell transmission model based on python
MIT License
41 stars 13 forks source link

Pre-load the cell with base flow #3

Open Jamespenglin opened 2 years ago

Jamespenglin commented 2 years ago

Hi, I'm wondering is there is way to pre-load the cells/links with base traffic flow to shorten the computation time. thanks,

yanyueliu commented 2 years ago

Hi, You can change the value of density column in supply.csv to set initial density of a link.

Jamespenglin commented 2 years ago

Awesome! That works out well! Thanks for the quick response!

Your CTP model assumed the ramp merge operation would use ratio or percentage of the ramp volume to enter the freeway mainline. Can you update the CTM for ramp metering control. That means the ramp enter rate is controlled by traffic signal. The most popular ramp metering control is using an algorithm called ALINEA. Here is the function to calculate the ramp entering rate:

R(t) =R(t-1) + k (Oc -O(t-1)

R(t)—— ramp enter rate (controlled by ramp signal) at time step t

R(t-1)---ramp enter rate (controlled by ramp signal) at time step t -1 (previous ramp enter rate)

K---Regulatory parameter defined by user

Oc——Critical Occupancy defined by user, it can be the freeway density when Q=Qmax

O(t-1) ——the Occupancy at time t-1, or freeway density at time t-1.

It will great if you can provide a CTM example for ramp merger with metering control.

Thank you!

Peng

On Apr 10, 2022, at 9:12 PM, yanyueliu @.**@.>> wrote:

Hi, You can change the value of density column in supply.csv to set initial density of a link.

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