Spiral Curves for Highway Alignment

#HorizontalCurves #HighwayDesign #DanielFindley

[@philanimkhize2656]

Best lecturer..I remember using this when I was on campus.Now I'm back for revision.

[@FindleyDaniel]

Thanks for the kind words, glad this was helpful for you!

[@NeilRobicheau]

Great video. My 20 year-old notes from college weren't making sense. You helped bring it all back. Thank you.

[@1TexasDallas]

Thank you! I haven't dealt much with spiral curves in over 30 years and your video helps.

[@FindleyDaniel]

You're welcome, I'm glad this was helpful for you!

[@Stacey-e4o]

Thank you!

[@FindleyDaniel]

You're welcome!

[@tran-set2420]

Great mini-lecture and explanation!

[@orlyjayberay5034]

Great Video Doctor Findley, as I was searching for an information about your research and background in transportation, I got interested on your book entitled "Highway Engineering - Planning, Design, and Operations, the 2nd edition" Is there any chance I can get a copy of this book I'm currently teaching as an Instructor in one of the university in the philippines. I want to learn more about Highway Engineering such as fundamentals with regards to this subject. Hoping for your response.

[@FindleyDaniel]

Great question - yes, from my understanding, you can confirm your instructor status and receive a free digital copy through Elsevier Educate - educate.elsevier.com/features I hope that will work for you, if not, please let me know and I'll see if I can find anything else out for you.

[@orlyjayberay5034]

@@FindleyDaniel Thank you for your response on my request Doctor Findley, I hope that I will be given an access on your book, it really means a lot.

[@orlyjayberay5034]

@@FindleyDaniel Good day Doctor Findley! I was not given access by Elsevier on your book, can you help me in securing a copy of your book? Thank you

[@jdagle]

Thanks for the video it was very helpful! I know you touched on how points could be located along a spiral by deflection, just like a horizontal curve but do you mind explaining the values that theta S/3 is multiplied by? It looks like a cursive L over another L squared?

[@FindleyDaniel]

The lowercase L is the arc length to any point along the curve and the uppercase L is the full spiral length.

[@jle1981]

Would it be important as a surveyor when locating a road or railroad tracks to locate not only an accurate as possible pc and pt begin and end but the pcc as best that they can actually visually tell in the field or has technology surpassed having to use these types of more old school methods in the field and the office side can calculate more efficiently now than is needed? I have been surveying for about 17 years and I started implementing an experiment so to speak where I indicated what I believe to be points of compound curvatures etc when I did a couple of projects that would have sidewalks designed crossing over railroad and highway right of ways. My forethought was that yes we have some pins marking the right of way east and west along the right of way but for safety sake I would want to see a tight check of the offset off of the edge of tracks, road etc to the row. I haven’t had a chance to work in the office before and never get a lot of good answers from them most of the time because they’re pretty busy but I was wondering if I’m just overthinking this or if I am on to something.

[@FindleyDaniel]

Johnny, great question! I'm not a surveyor, so I don't have the practical experience to give you a definitive answer, but the technology is capable of providing many additional incremental points, so I would suspect that more points are used.

[@derihilyas]

Hi I have a question for the PI that have different length of spirals, cause when I calculate this with normal formula it doesn't match with the one that I created with AutoCAD

[@FindleyDaniel]

That's correct, these equations are only for symmetric curves (with both spiral transitions equal).

[@derihilyas]

Do you perhaps have an equation for my case?

[@FindleyDaniel]

@@derihilyas Unfortunately, I don't think I've made a video on this topic yet - but it's on my list to complete.

[@derihilyas]

@@FindleyDaniel, Really appreciate your response, man. Also can't wait for the content to be released. But for now, do you have a link for kinds of literature/references about it?

[@FindleyDaniel]

@@derihilyas I think the textbook by Hickerson should have these detailed equations.

[@marksalvador8488]

when do we used spiral curve in road design?

[@FindleyDaniel]

Great question! Spirals are recommended according to the Green Book in Table 3-18. Beyond these values, the spiral transition doesn't add much value. This is based on p (the lateral offset) - if it is less than 2/3rds of a foot, the value will be minimal because drivers will introduce a spiral transition on their own anyway. From Table 3-18, as an example, at a design speed of 60 MPH, the maximum radius for the use of a spiral curve transition is 1,822 feet. So, for this example, if the curve has a radius larger than 1,822 feet, you don't need to use a spiral transition.

[@FindleyDaniel]

Mark, I've put together a new video on this topic, hope it helps you: kzbin.info/www/bejne/bneol2SmgLlredU

[@นิติกรมานะการ]

If Ls in not equal to Ls out. What the formular to calculate Ts

[@FindleyDaniel]

Great question! I'll check around to see if I can find equations for an asymmetric spiraled curve. They're not as common, but they are needed in some locations. Let me know if you find anything too. Thanks.

[@FindleyDaniel]

Here is the content from Hickerson that may be useful: drive.google.com/file/d/1YpD9pLtNpkgOR5U71ml9M81eUG9NmmiC/view?usp=sharing

[@FindleyDaniel]

This is the document - www.amazon.com/Route-Location-Design-Thomas-Hickerson/dp/0070286809

[@nellvincervantes3223]

Hi where is the Dc in the drawing?

[@FindleyDaniel]

Great question, the Dc represents the amount of curvature and is a function of the radius, so it isn't a directly displayed parameter of the curve, but is related to the curvature through a relationship with the radius. The equation is Dc = 18,000 / ( Pi x Radius )

[@nellvincervantes3223]

@@FindleyDaniel thanks you!

[@slimlady5817]

Hey can i ask you question please? I need help with that (it's down there)

[@slimlady5817]

If we have : the R , Front and back hooks, and O...but we can't get to PI and we can't use (Pc & PT) as a Fulcrum to drop curve stations...and also we can't get to O when you only have a device that measures angles and distances? And really thanks

[@FindleyDaniel]

Hello! If I understand your question correctly, I believe this information will help you: drive.google.com/file/d/1cAMyfVQw2WHE9c2VmI9uvLn2zUEv15Ip/view?usp=sharing

[@slimlady5817]

@@FindleyDaniel Oh sorry for my bad english...for simple curves I meant ( we can't reach the 4 points(P.I,PT,PC,O)) but we have R and both Tangent extension

[@FindleyDaniel]

@@slimlady5817 No worries! Here is the link for similar equations for a simple curve: drive.google.com/file/d/17wmtL1APeUvFUs5JmJjbRP_ZlKZ1Onc0/view?usp=sharing

[@slimlady5817]

@@FindleyDaniel thanks Daniel

[@marc4620]

hello can you derive some formulas of the spiral curves? thank you

[@jajataposlukas3030]

it is best to just memorize it, deriving the formulas from spiral is not recommended for me