 Hello viewers, I welcome you all for this today's session and analysis of Stopping Side Distance on Plain Ground. I am Ashok Kumar, Assistant Professor, Department of Civil Engineering, Valchand Institute of Technology, Solapur. The learning outcome of the today's session at the end of the lecture students will be able to analyze and calculate the stopping side distance on, stopping side distance on plain ground. Before we go into the analysis, let us understand what is stopping side distance. It is the minimum side distance available on a highway at any spot having a sufficient length to enable the driver to stop the vehicle travelling at a design speed safely without any collision with any other obstruction. So here you can take the three cases to understand the stopping side distance. It is just distance available for any driver in front of him to take proper action before meeting any object or any vehicle without having any collision. So considering this particular location where the vehicle negotiating on horizontal curve, here you can see that the sight line is restricted by the corner of the obstruction. Because of the obstruction, the sight line of the both drivers got reduced. So now what happened over here, the sight line is restricted and because of that, the distance between these two vehicles are going to be lesser. So by the point, there might have been an accident because of the shorter distance and driver unable to take any action in this first instant. Coming into the vertical curve here, the vehicle which is coming on the summit curve should be able to see the opposite vehicle well in advance or it may be any object or any pedestrian is causing anything that should be seen well in advance. Over here also because of the topography of this summit curve, if the topography kept very vertical, so in this case, the distance between the object and the driver will be very, very shorter. So that will again, they reduces the sight distance. In the third case, you can understand the vehicle negotiating on the main road and one vehicle coming on the crossroad. And here we can see the both the vehicles should see each other that is the vehicle from the main road also should see the vehicle coming from the crossroad. The both line, this is the sight line of the both the driver, this sight line is obstructed due to the corner obstructions of like any the building or any advertisement board. Because of this obstruction at the corner of the intersection, the sight line has restricted the both the driver and because of that, both are unable to see over each other. So might be they are coming very closer over here at the intersection, then they were able to see the both the vehicles. So by the time the distance left out in front of the driver will be very, very shorter. So for any designing the whether it may be horizontal curve or vertical curve or intersection, you must ensure yourself there is an along the alignment, you should have a proper sight distance so that the the distance available in front of the driver is sufficient to take a proper action as well as he perceives the any opposite vehicle or any pedestrian is crossing or animal is crossing whatever. So the distance should be sufficient for him to take an action. Now with this background, let us understand the how we are going to find out these stopping sight distance. This stopping sight distance is the distance some of the lag distance and the braking distance. So adding the lag distance and braking distance, we can get the what is the stopping sight distance. First we will calculate the lag distance, then we will go for calculating the braking braking distance. So lag distance is whenever the vehicle coming at a particular speed and as soon as the driver perceives the any object over here. So there is an object is coming or there is a pedestrian is crossing a vehicle is coming at that. So now as soon as he perceives the object and whatever the time elapsed between the perceiving the object that is during the reaction time of the driver, whatever the driver takes the time to go into this traveling during the reaction time t. So that is a distance we call as a lag distance. So here it is a distance the vehicle travel during the reaction time t. So here the action is not taken just his thinking process whatever the distance traveled in the during the thinking process that we call as the distance over here that is a D1 distance or you can say that is the distance of the lag distance. So once he decides that the action to be taken from here after reaching to the distance D1 he will apply the brake or he takes the action. So after application of the brake the again the further vehicle will go for a skidding. So that the distance is called as a braking distance that is a D2. So your stopping side distance is equal to D1 plus D2 that is lag distance plus your braking distance. So lag distance we know that the vehicle is coming up with the a particular speed here we know that the V and the reaction time t we can get the what is the lag distance here. If it is in meter per second it is a speed multiplied by the reaction time t. Okay so now t is usually taken as per the suggestion of the IRC we take the t value as a 2.5 second that is the reaction time of the driver is 2.5 second and if you want to convert into kmph we have to convert that into meter per second into kmph that is dividing by 1000 again dividing by 1000 into dividing by 60 into 60 that is conversion of meter into kilometer and conversion of second into minute and minute into hours. So this is how we calculate the conversion of meter per second into kmph that is 1 by 3.6 or 0.278 just multiply the this value of Vt into 0.278 you will get the V value in kmph. So now the lag distance in where V in kmph it is 0.278 V into t here V is in kmph. Now you pass over here and try to answer this question the value of F decreases with increase in speed that is true or false and higher the speed higher will be the stopping side distance. Now you can think for a while and try to give the answer for this question. I hope you are able to give the answer for this question. The correct answer is the the value of F decreases with increase in speed because it is coming with a certain design speed. So during the if the speed is higher you need to have the F value will be decreases with the increase in the speed. Now we know that the for the higher the the speed you need to take more longer distance to stop the vehicle. So again it is a true in this case also. Now we will go for calculating the your braking distance that is after the application of the brake how we are going to calculate the your braking distance. So now it is the distance travelled by the vehicle after the application of the brake. So for a level road it is obtained equate this the work done in stopping the vehicle and the kinetic energy of the vehicle. So vehicle is coming up with a certain momentum now the the opposite vehicle the opposite the force which is applied now you equate the one which is coming in the direction and which is opposing the this the your moment you can equate these two forces you can get the what is the braking distance here. So now here the work done against the friction force. So here the the friction force in stopping the vehicle is F into L or WFL. So whatever the friction force is W and to F into L where the W is the weight of the vehicle and F is the longitudinal friction and L is the your the braking distance. And this the this momentum we know that it is the kinetic energy it is in this direction we got the kinetic energy and opposite of the kinetic energy is nothing but your friction force. Now you equate this kinetic energy and friction force to get then the distance of your L value. Here the kinetic energy is given as half m e square they were v in meter per second. Now this is your friction force and this is your kinetic energy equate this kinetic energy and friction force it is WFL into WV square by 2g here W will get cancelled on both the side and the remaining is L equal to v square by 2gf where f is nothing but your longitudinal coefficient of friction here v is in meter per second. So total s is the equal to lag distance plus braking distance and we know that the lag distance is v into t and braking distance is v square by 2gf where v in meter per second. Now you want to give the conversion of equation to meter per second into kmph we know that it is the conversion of multiplying by 0.278 you can get the conversion from meter per second into kmph. So now conversion of the this one the 2gf here how we are going to put that put the gul as 9.81 and multiply by 2 you can get the how I got this 254f this is the explanation over here that is multiply by 0.278 square here in the numerator you have to multiply 0.278 to convert into meter per second into your kmph. So this is 0.278 square divided by 2 into 9.81 put the g value as 9.81 that comes 0.03. So you can simplify further 1 by 0.03 it will get the value of 254f. Now the as per the codal provision you can take the depending upon the speed of the vehicle you can take the f value as 0.4, 0.38 for more than 80 kmph we take the f value as 0.35. Now we will solve the simple numerical over here it is the the two cars are approaching in opposite direction the speed of the two cars has 90 kmph and 60 kmph and the coefficient of longitudinal friction is given as 0.7 and the break efficiency is 50% in the both the case. So now because the break efficiency is 50% I have to multiply this 0.7 by 0.5 to get the the value of your f. So I got the f value as 0.5 into 0.7 so I get the f value as 0.35. Now you calculate the your stopping side distance for car one that is vt plus v square by 2gf the both the values are given in kmph you have to convert into meter per second first. So dividing by 3.6 or multiplying by 0.278 whatever you can do it but here I got dividing by 3.6 the value for car one is 25 meter per second and car two is the 16.67 meter per second. Now you put the the v1 that is for car one the side distance is 153.6 and for car two it is 82.2 meter. Now you to get the total side distance you have to add both sd1 of car one and sd1 of car two. So total it becomes approximately it becomes 236 meter is the total side this total your stopping side distance on the road. These are the references I have used for preparing this presentation. Thank you.