Guess I'm an old hand, degree of curve was always the standard for design. Of course I long ago stopped laying out curves on line, still habits die hard.?ÿ
All the long segments are SE, giving us the orientation even without a N arrow, so th 12.00 and 17.14 ones are shown NE but one is labeled SE.
Well, if the delta was the given dimension then that's what I would use too.?ÿ If all you have is the arc length, radius and chord data though then who's to say what the delta is intended to be??ÿ But I think you are right about the chord length being the weak link.?ÿ The end of the arc rarely lands on the end of the chord but at least the bearing is maintained.?ÿ Hopefully that is enough to build an accurate curve.
My experience is that if I construct the ends of a curve using a chord bearing and distance, the computed radius and delta will not be the exact numbers (or proper second) they are intended to be, so I have always gone through the radius point, going 400.00 feet (in my example and assuming a tangent curve or where a radial bearing is given for non-tangent), use the labeled delta (left or right) then then back the 400.00 to the EC. The integrity of the numbers remain intact that way.
That's the way I handle curve data - I will use chord information as a check, but nothing more, if I have supplementary data. Draw the entry/exit tangents and fillet with the record radius, check the delta and arc length first before looking at chord info.
Nowadays I label the radial bearings at all curve PC/PTs on my plats, even if the curve is tangent. Gives the next guy a check on tangency, and an easy way to calculate/check the radius point.
They should make this website a requirement for the degree seeking students that need to experience the many and more or less correct ways you can lay out curves etc.
Man I love this site!
@spmpls?ÿ P.S.?ÿ The map example for this thread came out of your former agency.?ÿ Not casting any blame, mind you -- everyone makes mistakes!
NC requires chord bearing and distance so I add it below R and L.?ÿ In the Boone, NC area it seemed as though PLSs discovered horizontal curves in the 60s and 70s.?ÿ
Like most people, I'm drawn to symmetry like a moth to flame, but other than aesthetics, I don't see that tangent (or non-tangent) curves are a great improvement in many cases.?ÿ There's beauty in simplicity.?ÿ
Do you get physically ill when reviewing plans that have bizarre non symmetrical compound curves and convergent giant radius almost straight lines??
Just wondering (twitch....twitch...) ???? ???? ?????ÿ
Surely done after I departed, likely under contract to get all of the SSJDD parcels digitally mapped. I am sure that parcel number is a "levee" parcel number and not for the State Water Project.
As professionals it's helpful to have discussions with designers about some of these issues.
I believe it's been helpful when I have sat down with them.
The No.1 issue I've brought up is spirals in the ROW.
Then it's the jogs in and out slightly after a direction change. One of the designs from the early 2000's had numerous jogs before or after a TS or SC. The highway needs to flare out for cut/fill, culvert, drainage purposes but why do it 10' up station from a TS. For a 30' jog that's 300 sq ft. and even at $10,000 an acre that isn't $100. Way more than that is spent buying a $100 concrete ROW monument, installing it, writing the description, calculations, ect.?ÿ
I think it's helped, no more spiral ROW curves and legals, no more jogs slightly before or after direction changes and hopefully no more 1/4 degree curves, I think it's safe to say that a 1 degree curve covers almost all situations.?ÿ
It's a matter of cleaning up a ROW as much as possible and making them as clean as possible. Of course, there are times a ROW has to get very complicated, when it's up against senior lines and such. But out in the middle of ranch lands with no homes or development......that's a time for a simple design.?ÿ
Received a call from a fellow recently who was concerned with the true width of the right-of-way in a rural area where the road had been improved a great deal about ten years ago.?ÿ He was gong to bore under the road but the fence appeared to be in the wrong spot at the location where he was going to dig down to set his boring equipment.?ÿ This turned out to be a case of where the road designer had introduced several changes from the normal width to accommodate a longer culvert.?ÿ This was only a short distance from the corner of the landowner's property.?ÿ It made more sense to move the whole fence back several feet in this short distance than to set extra corner posts and brace posts in order to follow the exact right-of-way jogs.?ÿ Very short lengths of wire fence do not stay tight and are problematic in the long run.?ÿ Setting the extra corners and braces would also increase the cost substantially.?ÿ The landowner did what made sense to him.?ÿ The contractor was going to have a longer bore than anticipated as he couldn't set up where he had planned based on the road plans he had been provided.
I want the delta and the radius. Interesting to see what people prefer.
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I prefer the delta because it tends to give the correct (same as shown) out bearing on a tangent curve when I use CAD to calc it.?ÿ
My preferred method has become creating the two tangent lines and using the fillet command with the radius. I then can check the curve information. The question is always where to put the rounding on calcs in CAD.?ÿ
If provided the arc length you can back into the delta.?ÿ We encounter so many non-tangent curves it is handy to have the chord data to confirm the intent.?ÿ People screwup left and right so often it is amazing.
I grew up in a world where almost everyone can identify cardinal directions in a flash and know left from right.?ÿ My high IQ daughter still has to form an L with her left thumb and pointer finger to remember that is her left hand.?ÿ Tell her to go east or west and she'll get that right every time.
Chord bearing and length would be great.
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Around here, it is delta, length, radius, and (if you are lucky) a radial bearing IF the curve is non-tangent. I cannot remember seeing anything else on a plat or legal description. Of course, all of the data can be derived (backed in) given adequate information. I wouldn't mind chord bearing and length.?ÿ
For the most part, however, the arc length is the last thing I use in actually calculating curve.
@jitterboogie?ÿ lines that are seconds from being -//- And center lines with minor deflections for tenths over hundreds of feet...twitch twitch
Mules always used short chords for road design.?ÿ Following in their footsteps is a challenging task at times.
I am going to suggest that screenshot is quite possibly the final resolution of several poorly designed/coordinated road takings over the years and this is the "very complex" result.
By using the phrase "very complex", I must be feeling quite charitable today....?ÿ I would typically use much more colorful phraseology.?ÿ
I recently dealt with a much simpler, yet similar, issue.
