 Hello everyone. I welcome you all for today's session on fundamentals of traffic flow. Today we are trying to cover on sub-overly traffic volume. Myself, Pashok Kumar. Assistant Professor, Department of Civil Engineering. Walsh and the Institute of Technology, Sulapur. Learning outcomes of the today's session. At the end of the session, students will be able to calculate sub-overly traffic. As we know that overly volume is the main basis for a design and analysis of a traffic. But the variation of traffic within a given hour is also of considerable interest. So we always talk on overly volume, daily volume. But within an hour, there might be a variation in the traffic also. So as a traffic engineer, we must know that what is that and how it is going to vary it. A facility may have sufficient capacity to serve the peak-over demand, but a short-term peaks of flow within the hour may exceed the capacity and create a breakdown. It means, so overall in a delay, so there might be a peak-over and this peak-over is able to serve the required demand and fulfill the condition. But sometimes within the peak-over, there might be a 15-minute flow or 10-minute flow exceed the capacity and create the breakdown. Breakdown means there might be a condition of a traffic or the queue length is going to be caused on the particular location. So volume observed for a period of less than one hour are generally expressed as equivalent overly rates of full flow. For example, if 1000 vehicles are given to you for 15 minutes, an equivalent hourly rate flow is calculated by dividing 0.25 H. Suppose if you are taking a 15-minute, so in an hour, 4-15 minutes are exist. So 1 by 4, it gives a 0.25. So whatever the value given to you, for 15-minute rate of flow, it is given by 1000 divided by 0.25. So that gives you 4000 vehicles per hour. Actually it is a 15-minute flow, volume is converted into equally hourly rate of flow. Now let us understand little bit more about the volume and rate of flow. So whatever the traffic survey we conduct, it is a volume, a 15-minute volume, interval of 15-minute or 10-minute interval, 5-minute interval, whatever we take the interval of 15-minute, 10-minute or 5-minute. Now the survey is conducted from 5 to 6 p.m. In this one, each 15-minute flow is given 1000, 100, 1200 and 900. Now this volume is converted into equally rate of flow for every 15 minutes. So as I told you, 1 by 4, 0.25. So divide this 15-minute volume by 0.25. It gives you 4000 vehicles per hour. It is equivalent rate of volume of equivalent rate of flow of 15 minutes. So converting volume into equivalent rate of flow. So this is the main difference between the volume and rate of flow. The rate of flow, usually they are taken less than 1 hour and converted into 1 hour. So from 5 to 6, all the 15-minute volume are converted into equally rate of flow in terms of 1 hour. Now observe, say that the capacity of this location is 4200 per hour, vehicles per hour. Now in this condition, for 5 to 15 minutes, there is no any, the flow is not exceeding the 4200. So there will not be any problem with the 5 to 515. From 515 to 545, you can just say that the rate of flow is increasing the capacity of that particular location. Even though this 4200 is capable to serve the demand, but within an hour, we have the variation in the rate of flow. So this is what we are interested, the application of the calculation of the rate of flow is this only. So within the hour, there might be variation and we must, our facility must be able to ready to receive this variation of the demand. The actual flow per hour is 4200, but for 30 minutes from 515 to 545, we have a variation of the traffic within the hour. So this is the sub hourly volume or rate of flow we need to very much interested to know that. So in this one, the condition, it means that in each 15-minute period, the capacity is 4200 by 4, actually 15-minute flow should be 1050. This is theoretical, but actual rate of flow observed from 515 to 545 is 4400 and 4800. So this means this is exceeding the capacity and our facility will break down at this 30 minutes. So why it break downs? Because the actual rate of flow is 4400, that is exceeding the capacity of that particular location. So here we got some unused capacity, so actually the 4000 is there, our is 4200. This unused capacity will not be able to use it for a further time period. So from 515 to 545, we have a breakdown of the facility. So our facility must able to serve this capacity for this rate of flow. Further, what is the problem with this exceeding? Let us see in the next slide. Taking the same one, let us try to calculate what is the queue size is developing because of that 30 minutes. Capacity is increasing in that 30 minutes, that is 515 to 545. Now how to calculate the queue size? Queue size is calculated, initial there is no queue because this is 1050 is capable or this 1000 is capable or it is less than our capacity. So there is no issue with the queue at the first 15 minutes. Now how to calculate the queue size at the second one? Initial queue size plus arriving vehicles minus departing vehicles. So arriving is 1100, departing is 1050. So 15 number of vehicles is queued in the 515 to 530. Now again we have to take in the second initial is 50, arriving is 1200 and departing is 1050. So 200 number of vehicles are queued in the period of 530 to 545. And last one 545 to 6 pm we got another 15 number of vehicles is queued in this one. So this is what our facility is breaking down. If you are not capable, our facility is not capable to serve the demand. The form 30 minutes we got an issue with the capacity. So our facilities should be able to serve this issue for increasing the rate of flow. This is the advantage of calculating the rate of flow within the sub hour or within the peak hour volume. Let us define the another factor, peak hour factor. If you have the rate of hourly volume and maximum rate of flow, we can be able to calculate the peak hour factor. So this is the ratio between the hourly volume and the maximum rate of flow within the hour is defined as the peak hour factor. So put the hourly volume numerator and denominator maximum rate of flow. You have the 1 hour volume and you have the 15 minute volume. So you can calculate the what is the rate of peak hour factor for the 15 minutes. So volume divided by the 4 into 15 minutes. So in the 1 hour 4 15 minutes are there. So that is what we put a 4. Now another example we got a 2 hours survey from 4 to 6. In that a peak hour is observed is from 5 to 6. So within the 5 to 6 530 to 545 we got a 135 number of vehicles. Now how to calculate the peak hour factor? Let's add that 1 hour peak hour volume. So that comes as 464 and what is the 15 minute peak flow? It is 135. Now 4 multiplied by 135 at the denominator and 464 by that value it gives a 0.86 is the peak hour factor. Suppose if you have 5 minutes or 10 minutes volume that also that time also we can able to calculate that. What is the peak hour factor for 10 minutes? Peak hour factor for 5 minutes. If you are going for a 5 minutes so you divide it 60 by 5. So it comes here 12. 12 into 5 minute volume and total hourly volume. So that gives you peak hour factor for any kind of interval. Now let us pause this video and try to think and answer this question. What is the maximum and minimum possible peak hour factor for any kind of the traffic intensity? I hope you are able to give the answer for this. The answer is the maximum peak hour factor is 1 and a minimum is 0.25. Let us elaborate with a small example 1 9.25. So 1 happens when your 15 minute traffic is matching with the actual rate of flow. So 4200 by your 4 so that comes your 1050. So that times both are equal that your 15 there is no any variation in the 15 minute traffic. So whatever we are calculating 4200 by 4 it comes 1050 and your actual rate of flow is observed also 1050. Absolutely there is no variation in the peak hour within the peak hour. That time maximum value is 1. Minimum value we got 4200 it means it is your 1000 your 1 hour traffic is coming in the 15 minute. That case the minimum value comes as 0.25. So here like purely a completely a disaster or completely a breakdown of a facility. That time only this kind of value we can able to observe. It means 15 minute 1 hour traffic is coming in the 15 minutes. That is the worst condition any kind of the location we have. So that time we get a 0.25. So generally peak hour factor vary from 0.7 for rural section and 0.98 for a dense urban section. So this case also why lesser value for rural the condition in the rural section rarely happens in the rural section because of that little bit lesser value. And we need urban section we need a possibility of having congestion in the urban section. That is what we need to keep more preference for the urban sections. These are the references I have used for preparing this presentation. Thank you.