Hi, we are simulating a very congested area in Mexico City.

In our simulation we want the vehicles blocking the intersection; in actual Simtraffic simulation the vehicles stops before the intersection if the downstreet queue don´t let them pass.

How can we simulate the intersection blocked?

In real case, the intersection is blocked.

Thank you for your help.

Francisco

Hi Francisco,

Simulation models like SimTraffic have a logic that can either allow blocking, or not allow (not block sometimes and then not block others). So, SimTraffic has gridlock avoidence logic that does not allow vehicles to block the intersection. Otherwise, blocking would quickly begin to cause gridlock.

Thanks,

John.

John,

I have a case where I need to demonstrate that the area will be gridlocked because, I think, it would model 'reality'. If SimTraffic always incorporated the anti-gridlock logic, it might in some instances model an unrealistically optimistic scenario. Might I suggest an option in SimTraffic that allows intersections to be blocked.

Also, there is a condition that can occur on a four or six-lane street where left turns off of the main street into a driveway or side street can make the turn because oncoming traffic is stopped short of the intersection due to queueing ahead. If that occurs for the inside thru lane, but the outside thru lane is not queued back and the outside lane traffic does not stop short of the driveway, you have a very unsafe situation since the inside lane traffic is stopped short of the intersection due to queueing (usually from a left turn lane at a signalized intersection ahead) and the stopped thru traffic blocks the ability of the turning vehicle to see oncoming cars in the outside thru lane, so that when the vehicle turns left, they are unable to see oncoming traffic. Thus, I would prefer in many cases that the queuing traffic be permitted to queue through the next intersection instead of modelling something that I consider unsafe or unrealistic.

Also, you mentioned that some softwared did model queues through an intersection (i.e., allows queuing traffic to block an intersection). What software is it that does that?

Thanks,

Terry Brown
Albuquerque, NM

quote:

Originally posted by John Albeck:
Hi Francisco,

Simulation models like SimTraffic have a logic that can either allow blocking, or not allow (not block sometimes and then not block others). So, SimTraffic has gridlock avoidence logic that does not allow vehicles to block the intersection. Otherwise, blocking would quickly begin to cause gridlock.

Thanks,

John.

Hi Terry,

In older version of NETSIM, intersection blocking used to occur. However, this created complete gridlock in a network and the model would freeze up. I believe the newer version of NETSIM (CORSIM) do not block intersections.

Thanks,

John.