 I welcome you all for the today's session on Fundamentals of Traffic Flow. In this class, we will discuss about the Directional Design Avali Volume. Myself Ashok Kumar, Assistant Professor, Department of Civil Engineering, Walchand Institute Technology Solapur. Learning outcomes of the today's session, at the end of the session, students will able to calculate a Directional Design Avali Volume of the traffic. We know that traffic volume is expressed in daily volumes and hourly volumes. This daily volume is used for design and planning purposes, but it does not consider any variations within the day. Neither the ADT nor the ADT, average traffic, indicate the variations in the traffic volume that occur on the hourly basis during the day. This ADT and ADT consider the variations within a year and within a month or within a week also, but it does not consider the variations in the hourly basis during the day. So specifically, high traffic volume that occur during the peak hour of the travel. So peak hour, it means where within a one hour, you will be observing maximum number of traffic flowing in a within a one hour, that we call as a peak hour. So for the traffic engineer, he has to balance adequate facilities to be given for this kind of the peak hour traffic also or providing adequate level of service. So level of service, it means giving an proper speed, capacity, design of signal, all those things. Let us understand the peak hour volume. The hour with highest volume is referred as a peak hour volume. This peak hour within a day and within an hour in the day, you will be observing peak hour. It might be in the morning, busiest traffic hours in the morning or busiest traffic in the evening also. So this is used for capacity analysis of the highways and also used for designing and operational purposes. And this reflects the hourly variation of your traffic within a day. This diagram, you can understand what is a peak hour. So the service conducted for morning 12.30 am to the next day of 12.30 am. So within this the hour, the traffic between 7.30 or 9.30 will be observing the peak hours. Suppose that particular location, the capacity is maximally specified as 5000 number of vehicles per hour. So it is almost teaching the capacity. In the evening hours, the peak hour is going beyond the capacity. It means here the possibility of having congestion. If your facility is not able to cater this traffic, so this time there is a possibility of having a congestion or there is a queue length formation at this peak hour. So we need to consider this peak hours and design our facilities according to our peak hour volume. Peak hour volume is generally stated as directional volume. So each direction of flow is counted separately. Suppose if you are the service conducted on both side of the location and if you are considering there is no balance between the left side and right side traffic, you can calculate the peak hour volume direction wise also. So each direction we can calculate the separately. Comparison controls must be designed to adequate serve the peak hour traffic volume in the peak direction of flow, yes. And this peak hour volumes, how to calculate this peak hour volumes, whether we should take the highest hourly volumes, that is uneconomical, should we take the lowest, that is also uneconomical, should we take the average, that is inadequate. So now this peak hour is usually estimated from the projection of the ADT, that is average annual daily traffic. That term we are trying to refer as a DDHV, that is directional design hourly volume. Let us understand little bit more about this DDHV. So before we go into the DDHV, that is directional design hourly volume, let us understand the desired hourly volume. So this design hourly volume in both direction, adding both left side as well as right side traffic, this is used for the design. So that design hourly volume is taken typically 30th highest hourly volume. So this 30th highest hourly volume lies between 10th or 15th highest hourly volume. Usually we take in between of 10th and 50th, we take 30th highest hourly volume as a design hourly volume. So design hourly volume multiplied by equals to K into ADT, where K is the proportion of daily traffic occurring during the peak hour expressed as a decimal. So ADT you have A by D ADT and proportion of the ADT, we need to find out this K factor considering the 30th highest hourly volume. So that K factor specified in terms of decimal multiplied by the ADT gives the DHV. Let us understand little bit more about this 30th highest hourly volume. In the next axis I am taking the number of hours in one year with the traffic hours exceeding the shown over here. So within the hour, within a year I am trying to take the highest traffic over here with the shown in the exceeding the shown over here and Y axis I am taking the hourly traffic volume that is percentage of ADT. Now I am drawing the line over here 30th hourly volume, so from here it is getting the some decimal value that is percentage of ADT say here it is approximately 0.09 or 0.1 value. So 0.1 multiplied by the ADT that gives the design hourly volume. So proportion of ADT is your K factor. So what is the principle behind going with the 30th hour, why only 30th, why should not 10th, why should not 100, so all these things. So this 30th hourly volume how we are trying to find out if I take the highest hourly volumes in the year and put that in the descending order highest hourly volume suppose here in the January month or in the December month you got a highest hourly volume is 1000 vehicles per hour. Again in the next month what is in the hourly volume this might be lesser than this value, so lesser than this value. So just go on counting 1, 2, 3 like that and at 30th value what is the hourly volume that we are going to consider as the 30th hourly volume. So this 30th hourly volume indicates what this represents the volume that is exceeded in only 29 hours of the year it means 29 hour of the year traffic is exceeding this value rest of the hourly volumes are lesser than this value. If I consider over here if I take the 10th hourly volume yes it is exceeded only 9 times in the year but what about the facility which you are giving facility will be required more that is un economical. Again in the 100 hour the volume it is if I take the 100 hour the volume it is lesser and more condition at the particular location. So the K value which we usually take for urban location is 8 to 12 percent and 12 to 18 percent for a rural sections. So this is the principle behind the 30th hourly volume. Now you try to pass over here the question here if from the graph if you take K10 lowest or K100 highest what is the effect in the traffic stream. So pass for a while and try to think answer for this question. I hope you are able to give the answer for this question. As I told you in the previous slide if I take the K10 over here K10 the design hourly volumes comes higher. So only 9 hours you will be having congestion and rest hours we will be having a but it is goes for un economical. If I take K10 value it comes 0.15 or 0.2 0.2 multiplied by your ADT the volume will be more design hourly volume will be more. You are giving unnecessarily the more facility for that. If I take K100 value it is something like 0.05 it means 99 hours of the year it will be having a more congestion. So I should consider the 30th hourly volume not more not less. So if I take more lesser value more congestion in the traffic stream. So because of that we are taking the 30th hourly volume as the design hourly volume. Example if the ADT is given in 3500 vehicles per day and 30th ASLA volume is given as 420 so find out the K factor. So K factor is design hourly volume by ADT. So design hourly volume is 420 vehicles per day vehicles per hour sorry and 3500 vehicles per day so that gives you K factor is 12 percent. So now if you have the traffic not balanced on the left side and the right side traffic so you can calculate the directional design hourly volume also. So in the both side if your traffic is not balanced so this D factor is involved in calculating the directional design hourly factor the rest will remain same only we are adding the D factor. So these ADTs are converted to peak hour volume in the peak direction of flow this referred as the directional design hourly volume. So again K remains same this is the daily traffic occurring during the peak hour in decimal. So typically we take the 30th highest hourly volume and D is the directional distribution factor. So how to find out the D suppose here in the left side it is given as 300 and right side it is 700 so D factor is 700 by total traffic that gives you your D factor. And suppose from the table also we can calculate the we can get the K factor and D factor depending upon the facility you are giving for rural, suburban and in urban also for a radial route as well as for circumferential route you can take the K factor and calculate the DDHV that is directional design hourly factor. Another example of calculating the your directional design hourly volume giving the ADT of 33000 vehicles per day and 16 percent is your K value that is design hour is given as 16 percent of the ADT and 65 by 35 that is the directional distribution is given. So usually we take the highest direction distribution that is 65 so 0.65 multiplied by 0.16 into 33000 gives you directional design hourly volume these are the references I have used for representing this presentation thank you.