Thanks for the kind feedback. If it's helpful, I have organized similar videos in playlists on this page: sites.google.com/ncsu.edu/daniel-findley/educational-resources
Thanks! Glad you liked the video - I have organized the engineering-related videos into playlists on this page, if it's helpful for you: sites.google.com/ncsu.edu/daniel-findley/educational-resources
Thanks for the comment - I recently organized my highway design related videos into better playlists on youtube. I've also summarized them here - sites.google.com/ncsu.edu/daniel-findley/educational-resources
Does the PVI always at the center of the vertical curve length? I am confuse..for instant, i will exaggerate the grade value to explain this. Let say the entry grade is 5% while the exit grade is 30%..isnt that obvious that the PVI will be at the right hand side of the middle vertical curve distance?
Yes, that's correct - for a symmetric, parabolic curve, the PVI will always be at the center. This is the most common and default type of vertical curve, so you should be safe with this assumption unless otherwise stated.
Why do we take e=y... we are taking y as elevation whereas e is clearly difference of elevation between elevation of PVI and Point on curve right below PVI. Wouldn't that be.. e= PVI-y= (G1*L/2) - AL/8
Below is a list of vertical curve videos that I've made, I can't recall exactly what scenarios I created for each though. Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
The key for this type of problem is to make sure you have the right sign (+ or -) associated with each grade. If you do that, everything should work out!
I solved a problem where the PVC elevation was greater than the PVI elevation. Looking at the vertical curve, it looks like the PVI should always have the highest elevation. How come this isn't the case?
Great question! There are 6 possible scenarios when analyzing a vertical curve. These 6 scenarios fall into either sag or crest curves. Sag curves (with a concave up shape) g1 = negative and g2 = positive OR g1 = postive and g2 = steeper positive than g1 OR g1 = negative and g2 = flatter negative than g1 Crest curves (with a concave down shape) g1 = positive and g2 = negative [this is the scenario in this video] OR g1 = positive and g2 = flatter positive than g1 OR g1 = negative and g2 = steeper negative than g1
Of those six scenarios, two could lead to a situation with the PVC elevation greater than the PVI elevation: Sag with g1 = negative and g2 = flatter negative than g1 Crest with g1 = negative and g2 = steeper negative than g1
Why do we delve deep into the science and mathematics of different curve types like circular and parabolic for highway design when, in practice, modern software tools render them perfectly identical for vertical crest curves? Isn't the distinction becoming more theoretical than practical, given that most software defaults to a circular representation?
I'm not familiar with agencies switching to circular arcs instead of parabolic curves for vertical alignment. Parabolic curves fit the terrain better and provide a smoother transition for vehicles (relative to a circular arc). For horizontal curves though, yes, circular arcs are the most common. I have a few videos showing horizontal and vertical curve designs. Here's an example of a vertical curve, using parabolic equations: th-cam.com/video/zhM-CKkan5M/w-d-xo.html
@@FindleyDaniel thanks for reply - I would agree with you but if you draw curves (circular or parabolic) in C3D or ORD Bentley - they look identical no matter how much you change gradients or exaggeration - I asked Bentley and they told me - It's mostly true that there are no visual differences. One of the differences isn't in what you can see, but in how they behave in combination with other elements - so no point to teach parabola - software doesn't reproduce it sadly
@@Call.of.the.mountains Interesting, do they show up correctly on design plans (I would assume that one some vertical curves there is a substantial difference based on the elevation increments).
@@FindleyDaniel it used to be like this in MX but now bentley made it too simple sadly. If you can send me an image to show comparison between the two - maybe I can tell them that software is producing design in error
Why your formula a=(g2-g1)/2L vs CERM r=(g2-g1)/L. Anyone can explain the reason is greatly appreciated. I’m confused why the divisor in your formula is 2L instead of just L🤷🏻♀️ But then CERM eq. 79.47 use your “a” formula with “2” when it’s substituted in the parabola general formula rx^2/2___my assumption is “a” formula to calculate the initial elevation or PVC and “r” is the formula use to determine the succeeding elevations per rate of change in slope 🧐
Unfortunately, I don't have my copy of the CERM at home, so I can't see exactly what you're referring to. You can try this method and the CERM method and see if you get the same results - that may help you determine what the difference is.
This video helps explain how and when you need to know when a curve is a crest or sag: th-cam.com/video/UuOP9n9cWnc/w-d-xo.html And, here are some additional vertical alignment topics that might be useful for you: Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html Vertical Alignment Example - th-cam.com/video/C6hkRgT8Iz0/w-d-xo.html Vertical Alignment Example - th-cam.com/video/5CL5lsHtUPQ/w-d-xo.html Vertical Alignment Information from Google Earth - th-cam.com/video/xAypCxEzw6k/w-d-xo.html Extracting Vertical Information from Google Earth - th-cam.com/video/HEibf1biICg/w-d-xo.html Parabolic Equation from Google Earth Information - th-cam.com/video/9RvianxZ4tM/w-d-xo.html L=KA - th-cam.com/video/UuOP9n9cWnc/w-d-xo.html Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
This is probably a useful one for you: Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html Here is my full list of vertical alignment videos: Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html Vertical Alignment Example - th-cam.com/video/C6hkRgT8Iz0/w-d-xo.html Vertical Alignment Example - th-cam.com/video/5CL5lsHtUPQ/w-d-xo.html Vertical Alignment Information from Google Earth - th-cam.com/video/xAypCxEzw6k/w-d-xo.html Extracting Vertical Information from Google Earth - th-cam.com/video/HEibf1biICg/w-d-xo.html Parabolic Equation from Google Earth Information - th-cam.com/video/9RvianxZ4tM/w-d-xo.html L=KA - th-cam.com/video/UuOP9n9cWnc/w-d-xo.html Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
This can't be correct when you talk about the grades. I've seen a million problems where the grades are put in their decimal form. But I do have one question about grades: I've also seen that sometimes they use their absolute value and sometimes they don't. How do you know when to use the absolute value and when not to?
That's correct - it's not impossible to use other units. However, with the equations presented and for the sake of consistency, you should pick a method and stick with it. From a units perspective, having grades in percent and distances in stations works out (each is in 100s), which is why I present the equations that way and recommend that method. In general, the sign (+ or -) of the grade is critical and should be associated with the grade. However, there are cases when the sign isn't necessary, including when calculating the external distance (distance from the PVI to the curve) and when using the formula L=KA (where A is the algebraic difference in grades - though this application still accounts for the grades because the K value is specific to the vertical curve type).
Explanation is clear as can be, subscribed.
thanks a lot sir, learned a lot from this video alone than in my 3hrs Sat class
Very Clear & Concise! Thank you.
Thanks for the kind feedback. If it's helpful, I have organized similar videos in playlists on this page: sites.google.com/ncsu.edu/daniel-findley/educational-resources
Great breakdown
hands down the best video
That's very kind, thank you!
@@FindleyDaniel sir Thanks
Brilliant video. It helps a lot indeed. Thanks.
Thank You Sir. Clear explanation
Thanks for your help
I develop my knowledge of vertical curve elements
Very helpful thank you
New subscriber right here! thank you
Thanks! Glad you liked the video - I have organized the engineering-related videos into playlists on this page, if it's helpful for you: sites.google.com/ncsu.edu/daniel-findley/educational-resources
Excellent! Good stuff! More examples more examples, I say! WHOO!
Thanks for the comment - I recently organized my highway design related videos into better playlists on youtube. I've also summarized them here - sites.google.com/ncsu.edu/daniel-findley/educational-resources
Does the PVI always at the center of the vertical curve length? I am confuse..for instant, i will exaggerate the grade value to explain this. Let say the entry grade is 5% while the exit grade is 30%..isnt that obvious that the PVI will be at the right hand side of the middle vertical curve distance?
Yes, that's correct - for a symmetric, parabolic curve, the PVI will always be at the center. This is the most common and default type of vertical curve, so you should be safe with this assumption unless otherwise stated.
@@FindleyDaniel well explained. Thank you Prof Findley 👍🏻👌🏻
Why do we take e=y... we are taking y as elevation whereas e is clearly difference of elevation between elevation of PVI and Point on curve right below PVI. Wouldn't that be..
e= PVI-y= (G1*L/2) - AL/8
This referring to the lowercase "y" which is the tangent offset that is described at 3:21 (th-cam.com/video/qZVZyf_9r2k/w-d-xo.html).
Hello and thanks , Do you have an example for positive g1 and g2 or negative g1 and g2 whit lower and higher point in the curve
Below is a list of vertical curve videos that I've made, I can't recall exactly what scenarios I created for each though.
Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html
Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html
Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html
Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html
High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html
High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
The key for this type of problem is to make sure you have the right sign (+ or -) associated with each grade. If you do that, everything should work out!
Please give me a video of the following example sir
Absolutely, here is a playlist of vertical alignment which has a variety of example problems: th-cam.com/play/PLQ2tBMRKXROZsDv_W9Ax-ytgp5x3y2BQX.html
Subscribed and downloaded
Thanks!
thank u thats help me a lot
Very good
I solved a problem where the PVC elevation was greater than the PVI elevation. Looking at the vertical curve, it looks like the PVI should always have the highest elevation. How come this isn't the case?
Great question! There are 6 possible scenarios when analyzing a vertical curve. These 6 scenarios fall into either sag or crest curves.
Sag curves (with a concave up shape)
g1 = negative and g2 = positive
OR
g1 = postive and g2 = steeper positive than g1
OR
g1 = negative and g2 = flatter negative than g1
Crest curves (with a concave down shape)
g1 = positive and g2 = negative [this is the scenario in this video]
OR
g1 = positive and g2 = flatter positive than g1
OR
g1 = negative and g2 = steeper negative than g1
Of those six scenarios, two could lead to a situation with the PVC elevation greater than the PVI elevation:
Sag with g1 = negative and g2 = flatter negative than g1
Crest with g1 = negative and g2 = steeper negative than g1
اللهم صل على محمد وعلى اله وصحبه اجمعين
Why do we delve deep into the science and mathematics of different curve types like circular and parabolic for highway design when, in practice, modern software tools render them perfectly identical for vertical crest curves? Isn't the distinction becoming more theoretical than practical, given that most software defaults to a circular representation?
I'm not familiar with agencies switching to circular arcs instead of parabolic curves for vertical alignment. Parabolic curves fit the terrain better and provide a smoother transition for vehicles (relative to a circular arc). For horizontal curves though, yes, circular arcs are the most common. I have a few videos showing horizontal and vertical curve designs. Here's an example of a vertical curve, using parabolic equations: th-cam.com/video/zhM-CKkan5M/w-d-xo.html
@@FindleyDaniel thanks for reply - I would agree with you but if you draw curves (circular or parabolic) in C3D or ORD Bentley - they look identical no matter how much you change gradients or exaggeration - I asked Bentley and they told me - It's mostly true that there are no visual differences. One of the differences isn't in what you can see, but in how they behave in combination with other elements - so no point to teach parabola - software doesn't reproduce it sadly
@@Call.of.the.mountains Interesting, do they show up correctly on design plans (I would assume that one some vertical curves there is a substantial difference based on the elevation increments).
@@FindleyDaniel it used to be like this in MX but now bentley made it too simple sadly. If you can send me an image to show comparison between the two - maybe I can tell them that software is producing design in error
@@Call.of.the.mountains This video shows one, is that clear enough: th-cam.com/video/zhM-CKkan5M/w-d-xo.html
Thank You Sir
Why your formula a=(g2-g1)/2L vs CERM r=(g2-g1)/L. Anyone can explain the reason is greatly appreciated. I’m confused why the divisor in your formula is 2L instead of just L🤷🏻♀️ But then CERM eq. 79.47 use your “a” formula with “2” when it’s substituted in the parabola general formula rx^2/2___my assumption is “a” formula to calculate the initial elevation or PVC and “r” is the formula use to determine the succeeding elevations per rate of change in slope 🧐
Unfortunately, I don't have my copy of the CERM at home, so I can't see exactly what you're referring to. You can try this method and the CERM method and see if you get the same results - that may help you determine what the difference is.
What is the usage of crest and sag ?
This video helps explain how and when you need to know when a curve is a crest or sag: th-cam.com/video/UuOP9n9cWnc/w-d-xo.html
And, here are some additional vertical alignment topics that might be useful for you:
Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html
Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html
Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html
Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html
Vertical Alignment Example - th-cam.com/video/C6hkRgT8Iz0/w-d-xo.html
Vertical Alignment Example - th-cam.com/video/5CL5lsHtUPQ/w-d-xo.html
Vertical Alignment Information from Google Earth - th-cam.com/video/xAypCxEzw6k/w-d-xo.html
Extracting Vertical Information from Google Earth - th-cam.com/video/HEibf1biICg/w-d-xo.html
Parabolic Equation from Google Earth Information - th-cam.com/video/9RvianxZ4tM/w-d-xo.html
L=KA - th-cam.com/video/UuOP9n9cWnc/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html
High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html
High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
Can show example,Simplify the example💜
This is probably a useful one for you:
Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html
Here is my full list of vertical alignment videos:
Vertical Curve Fundamentals - th-cam.com/video/qZVZyf_9r2k/w-d-xo.html
Parabolic Equation - th-cam.com/video/OJYDhdcV6KM/w-d-xo.html
Vertical Curve - th-cam.com/video/4gUxo1jhu4s/w-d-xo.html
Vertical Curve Example - th-cam.com/video/884ca7ZDVyM/w-d-xo.html
Vertical Alignment Example - th-cam.com/video/C6hkRgT8Iz0/w-d-xo.html
Vertical Alignment Example - th-cam.com/video/5CL5lsHtUPQ/w-d-xo.html
Vertical Alignment Information from Google Earth - th-cam.com/video/xAypCxEzw6k/w-d-xo.html
Extracting Vertical Information from Google Earth - th-cam.com/video/HEibf1biICg/w-d-xo.html
Parabolic Equation from Google Earth Information - th-cam.com/video/9RvianxZ4tM/w-d-xo.html
L=KA - th-cam.com/video/UuOP9n9cWnc/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point - th-cam.com/video/nn6_RliorAw/w-d-xo.html
Passing a Vertical Curve Through a Fixed Point Example - th-cam.com/video/ADTbmlMo2UM/w-d-xo.html
High /Low Point - th-cam.com/video/1pGM2tjEbt4/w-d-xo.html
High /Low Point - th-cam.com/video/h0-zhBIXaWM/w-d-xo.html
This can't be correct when you talk about the grades. I've seen a million problems where the grades are put in their decimal form. But I do have one question about grades: I've also seen that sometimes they use their absolute value and sometimes they don't. How do you know when to use the absolute value and when not to?
That's correct - it's not impossible to use other units. However, with the equations presented and for the sake of consistency, you should pick a method and stick with it. From a units perspective, having grades in percent and distances in stations works out (each is in 100s), which is why I present the equations that way and recommend that method.
In general, the sign (+ or -) of the grade is critical and should be associated with the grade. However, there are cases when the sign isn't necessary, including when calculating the external distance (distance from the PVI to the curve) and when using the formula L=KA (where A is the algebraic difference in grades - though this application still accounts for the grades because the K value is specific to the vertical curve type).
Sa AGÜ
Thanks for your help