a very new Idea

[walid]

Hi

my friend asked my help in his design
he wants some sensors placed some where in a gate that counts the visitors come in or out. when the number inside the room is say ten, the gate must closed and prevent more people from inteing

i tell him that he may use a controller like PIC16F84A and use two pair of IR TX and RX placed like to horizontal parallel lines one pair connected to say A1 port as i/p and the other pair to another i/p say A2
if a person cut ir connected to A1 then A2, then, this person is assumed to be entering the gate
if A2 then A1 he is out
the cotroller sums or substract till ten and close the gate for some period of tme

My questions:

(1) is this idea is the best for this progect or not?
(2) if it is OK can you help me in designing these sensors, the Tx is an IR diod connected to pin 3 of 555 IC. and the infrared receiver module .....

i need you help may be some links or any thing else
thanks