As per IRC, when designing pedestrian and traffic signals using approximate method for a two-phase system, the minimum initial period with pedestrian signal should NOT be less than:

Explanation:

Design method as per IRC Guidelines:

1. The pedestrian green time required for major and minor roads are calculated on a walking speed of.1.2 m/sec and initial walking time is 7 secs. These are the minimum green time required for vehicular traffic on the minor and major roads respectively
2. The green time required for vehicular traffic on the major road is increased in proportion to the traffic on the two approach roads
3. The cycle time is calculated after allowing amber time of 2 secs each.
4. The minimum green time required for clearing vehicles during a cycle is determined for each lane of the approach road assuming that the first vehicle will take 6 sec and the subsequent vehicles of the queue will be cleared at the rate of 2 secs. The green time required for vehicular traffic on any of the approach road is limited to 16 secs.
5. The optimum signal cycle time is calculated using Webster's method.

 Additional InformationWebster's Formula:

Webster's method of traffic signal design is an analytical approach of determining the optimum signal cycle time, C_o corresponding to minimum total delay to all the vehicles at the approach roads of the intersection.
The optimum signal cycle is given by the relation:
\(C_0=\frac{1.5L+5}{1-Y}\)
Where,
L= total lost time (sec)= 2n +R
n= number of phase
R = all red time or red-amber time
Y =y₁+ y₂ (the value of Y should be less than 1)
Here, y1 = q1/s1 and y2 = q2/s2
O = Normal flow
S = Saturation flow