Traffic modleing/Systems of Equations

[techb]

This is for a friend, but I don't even really understand on what is going on. I think it is college math of some kind, judging by ask for equations, I'm assuming it is Algebra.

anybody who knows a little about traffic modeling or systems of equations can you please help me with this? I have to create a system of equations to model the traffic flow in the attached diagram. it follows the principle flow-in = flow-out but the problem is I don't know how much is flowing through the center so I can't figure out how to write the equation. I know the first intersection has 800 cars entering an hour so that means 800 also has to leave that intersection but the only variable I have for it is A. I'd really appreciate any help that can be given. This is my homework but I created this diagram myself to be similar to the actual assignment so I'm not asking for answers or anything, just how to look at this. The example in the book only has 4 streets

Any light to shed on this?

[Mordred]

I don't know about advanced algebra or anything, but if I'm not missing some hidden complicated point the idea is simple

traffic in = traffic out <=> sum (traffic in / street) = sum (traffic out / street)
<=> (traffic.in.street.1+traffic.in.street.2+...+traffic.in.street.n) = (traffic.out.street.1+traffic.out.street.2+...+traffic.out.street.n)

and that's the equation. I guess you can involve more parameters like a weighted function by assigning weights depending on the size of the street or the maximum traffic flow it can handle. It's just a matter of customizing I guess.

I hope this helps.

[techb]

More than what I gathered, I was thinking something about the cars turning at the intersections making the in and out numbers vary, but I think I was looking at it wrong. I was too literal with it.

But like explained this is for a friend, I am not in the class, nor have gotten this far in algebra. I have started watching lectures on trig and calc though, yet unrelated.

I have given le friend a link to this thread, and go from there. Thanks to all and any input.

[Axon]

Use differential equations.  Check these links, they may shed some light on this.

en.wikipedia.org/wiki/Traffic_flow
math.mit.edu/projects/traffic/