Are banked curves used anywhere to allow high speed turns on public roads?
Yes everywhere, those are standard highway design standards. Referred to superelevation by civil engineers.
Quote from: Big John on February 19, 2025, 12:00:17 PMYes everywhere, those are standard highway design standards. Referred to superelevation by civil engineers.
Really? I haven't noticed them.
Quote from: kernals12 on February 19, 2025, 11:50:02 AMAre banked curves used anywhere to allow high speed turns on public roads?
Ever heard of the West Virginia Turnpike? In addition to high banking in many of its tight curves, the Turnpike actually has some high reverse banking in a few curves that allow both sets of lanes to remain on the same plane (most likely to simplify the curve drainage, but there are other possibilities).
Quote from: kernals12 on February 19, 2025, 12:03:27 PMQuote from: Big John on February 19, 2025, 12:00:17 PMYes everywhere, those are standard highway design standards. Referred to superelevation by civil engineers.
Really? I haven't noticed them.
Really really...
Quote from: kernals12 on February 19, 2025, 12:03:27 PMQuote from: Big John on February 19, 2025, 12:00:17 PMYes everywhere, those are standard highway design standards. Referred to superelevation by civil engineers.
Really? I haven't noticed them.
Here's one within walking distance of my grandmother's house on US 64. It was more obvious when it was still 2-lane...
https://maps.app.goo.gl/AgAZXN5gf8dDirpc9
Okay, I think I was wondering about steeply banked curves
Kernals, best example I can give from your old home area is watching snow from snow banks melt. That will give you a good sense in some curves with how they are banked by watching the melt descend across from one side to the other.
This one is terrific to drive at 55 mph because it's a double banked curve set with almost no level piece between the two. So when you change to opposite banking there is a cool visual and sensory effect:
https://maps.app.goo.gl/CwwDjQHKg53dp8er5
Quote from: kernals12 on February 19, 2025, 12:12:45 PMOkay, I think I was wondering about steeply banked curves
Do you mean the sort of thing you see on some NASCAR racetracks?
Quote from: kernals12 on February 19, 2025, 12:12:45 PMOkay, I think I was wondering about steeply banked curves
Quote from: 1995hoo on February 19, 2025, 01:18:22 PMDo you mean the sort of thing you see on some NASCAR racetracks?
This doozy across the Cabin Creek bridge (https://www.google.com/maps/@38.1954621,-81.4783485,3a,15y,280.55h,87.56t/data=!3m7!1e1!3m5!1sbLwcy8FBbIVPsO6_Y4jNZw!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D2.440695069853035%26panoid%3DbLwcy8FBbIVPsO6_Y4jNZw%26yaw%3D280.55083891386397!7i16384!8i8192?entry=ttu&g_ep=EgoyMDI1MDIxMi4wIKXMDSoJLDEwMjExNDU1SAFQAw%3D%3D) is much steeper than it looks on GSV, particularly in the southbound direction (coming towards this view). I don't think that it is the steepest banking on the West Virginia Turnpike, but it is probably most notorious.
Flyovers are often pretty significantly banked.
BTW, Google found the following: https://www.aaroads.com/forum/index.php?topic=33727.0
I recall from my youth that some of the curves on the Taconic State Parkway in NY were banked the wrong way. That's even more exciting.
Quote from: pderocco on February 19, 2025, 02:35:57 PMFlyovers are often pretty significantly banked.
This is especially noticeable if you're stuck in a traffic jam on it.
Banked curves nowadays are standard. They don't have to be like Talladega, just enough to allow reasonable speed to be kept.
One of the first times I drove a car myself in Kansas I was surprised at how much more banked the curves were on the then-recently reconstructed sections of I-35 east of Emporia than I was used to in Oklahoma. It felt almost like the road was driving itself.
Quote from: 1995hoo on February 19, 2025, 01:18:22 PMQuote from: kernals12 on February 19, 2025, 12:12:45 PMOkay, I think I was wondering about steeply banked curves
Do you mean the sort of thing you see on some NASCAR racetracks?
That's what I'm thinking he's thinking. But he's also probably missing the connection that a banked curve on a NASCAR oval is designed for 150 mph speeds. Comparably, a banked curve on a 65 mph roadway or a 35 mph roadway doesn't need to have the same superelevation.
As for examples, there's several I can think of, but this is probably my best: I-95 North as it curves over I-295 South near Wilmington, DE.
View of support piers on 295: https://maps.app.goo.gl/DHiK8UBMQUUw5YBP8
View on 95: https://maps.app.goo.gl/GTss5bcCwX4sLgyN7 It's tough to tell in a picture, but the roadbed on the right shoulder will be higher than the car's roof in the left lane.
Quote from: jeffandnicole on February 19, 2025, 10:05:38 PMQuote from: 1995hoo on February 19, 2025, 01:18:22 PMQuote from: kernals12 on February 19, 2025, 12:12:45 PMOkay, I think I was wondering about steeply banked curves
Do you mean the sort of thing you see on some NASCAR racetracks?
That's what I'm thinking he's thinking. But he's also probably missing the connection that a banked curve on a NASCAR oval is designed for 150 mph speeds. Comparably, a banked curve on a 65 mph roadway or a 35 mph roadway doesn't need to have the same superelevation.
As for examples, there's several I can think of, but this is probably my best: I-95 North as it curves over I-295 South near Wilmington, DE.
View of support piers on 295: https://maps.app.goo.gl/DHiK8UBMQUUw5YBP8
View on 95: https://maps.app.goo.gl/GTss5bcCwX4sLgyN7 It's tough to tell in a picture, but the roadbed on the right shoulder will be higher than the car's roof in the left lane.
But I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Quote from: kernals12 on February 19, 2025, 11:50:02 AMAre banked curves used anywhere to allow high speed turns on public roads?
Have you been on public roads?
Not in place anymore, but a NASCAR-style banked curve was technically part of a public road in Berlin at one point...but only as a purpose-built connection when that expressway/Autobahn was used as the AVUS racetrack.
https://www.reddit.com/r/formula1/comments/ee5tg4/avus_and_its_famous_43_banking/
Though racing would continue on this expressway circuit (not even the only one Germany ever had) into the mid-90s, the banked section was dismantled by the end of the sixties.
Google Maps of where the racetrack used to be, with the Autobahn still in use to this day for Berlin commuters:
https://www.google.com/maps/search/AVUS+berlin+map/@52.4627565,13.1624513,12z/data=!5m1!1e1?entry=ttu&g_ep=EgoyMDI1MDIxNy4wIKXMDSoASAFQAw%3D%3D
---
Intentionally going this route on the same theme:
The Nurburgring Nordschleife racetrack, also in Germany, (former Formula One circuit, still holds touring car races on the regular including a yearly 24 hour event) is a public road on non-race days, where for a toll anyone can experience driving one of the most legendary motorsports circuits in the world. It has a low-speed banked turn that has become an iconic vantage point:
https://www.roadandtrack.com/motorsports/a20745890/mastering-the-nurbugrings-most-famous-corner/
https://newsroom.porsche.com/en/2020/motorsports/porsche-nuerburgring-nordschleife-caracciola-karussell-22455.html
Quote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Higher superelevation = more dirt work = more expensive
Quote from: Scott5114 on February 20, 2025, 06:18:12 AMQuote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Higher superelevation = more dirt work = more expensive
also less control for the non-professional drivers. Also problemic in northern climates where sliding is more likely to occur in slippery conditions.
Quote from: Big John on February 20, 2025, 06:44:12 AMQuote from: Scott5114 on February 20, 2025, 06:18:12 AMQuote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Higher superelevation = more dirt work = more expensive
also less control for the non-professional drivers. Also problemic in northern climates where sliding is more likely to occur in slippery conditions.
Also, steeper banks require a minimum speed to keep from sliding down the banking. On some NASCAR tracks that speed is well above 40 mph. To have that on a public road would mean you couldn't have a vehicle have a mechanical problem or have to brake for any reason within the curve without risking head on collisions.
Maybe the next technical breakthrough would be a road that senses the speed of the vehicles on it, and increases or decreases the banking of the road to compensate. That way the 150 mph cars could keep going strong, yet grandma on the way to bingo could putter along at her pace.
(where's that sarcasm emoji?)
Quote from: kernals12 on February 19, 2025, 11:50:02 AMAre banked curves used anywhere to allow high speed turns on public roads?
DC Beltway east of Rockville Pike. Aka the Rock Creek Rollercoaster. Recall a Driver's Ed teacher (1973) saying it had the largest such banks on the interstate system, and in icy weather cars could slide sideways. Not saying that's true, but...
Quote from: GaryV on February 20, 2025, 07:41:40 AMMaybe the next technical breakthrough would be a road that senses the speed of the vehicles on it, and increases or decreases the banking of the road to compensate. That way the 150 mph cars could keep going strong, yet grandma on the way to bingo could putter along at her pace.
(where's that sarcasm emoji?)
And if it detects a car without a license plate, it banks up super fast and tosses the car clear into the next county!
Quote from: Scott5114 on February 20, 2025, 08:27:12 AMQuote from: GaryV on February 20, 2025, 07:41:40 AMMaybe the next technical breakthrough would be a road that senses the speed of the vehicles on it, and increases or decreases the banking of the road to compensate. That way the 150 mph cars could keep going strong, yet grandma on the way to bingo could putter along at her pace.
(where's that sarcasm emoji?)
And if it detects a car without a license plate, it banks up super fast and tosses the car clear into the next county!
Or a "low polygon count pickup truck", for that matter.
Quote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Great question. This is a three dimensional puzzle that confounds the civil engineers when designing high-speed railroad trackage (and similar other technologies). The simple concept is that the centerline of the [lane] needs to be rotated at a constant rate (called "roll rate") until the design superelevation is achieved. In theory, you want the entire section of tight curve radius to be set at the design superelevation, but the spiral rate into the curve radius seldom can be coordinated with the roll rate, which at some point also needs to be spiraled. This is where it gets tricky, as the design line needs to split from the centerline to both the top-of-curve and the bottom-of-curve (each with their own curve designs).
On railroads, the spiralling of superelevation is simple because we are stuck with crossties that are straight and flat. On rubber-tired trains, the guideway design gets tricky because there is a tendency to "scoop out" the centerline (which is exactly what you see on a NASCAR track). Since we calculate the G-forces on passengers (hence the maximum curve speed) based on the characteristics of the centerline [of each lane], calculating the effective superelevation versus curve radius when you are "rolling" and/or "spiralling" into both the curve radius and the banking is a mathematical problem that is not for the timid. And this is often more important to establishing the "maximum safe speed" than when in the peak of the banked curve.
Worse, unlike NASCAR we railroaders and highway guys also have to address changes in vertical curves. When I've been on the design teams, I won't let the designers play with both horizontal and vertical curves at the same time so we won't mess up the "maximum safe speed" calculations.
Quote from: jeffandnicole on February 19, 2025, 10:05:38 PMBut he's also probably missing the connection that a banked curve on a NASCAR oval is designed for 150 mph speeds.
It's K12. That's probably why he wants them - for the 150 mph AI cars.
There was a pretty funky banked curve on the Mountain Parkway just east of Exit 53 (the KY 1010/Hazel Green exit) that got reworked during a recent pavement rehab project, then completely obliterated as the widening project continues.
Quote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
I once drove an unpaved road that had a pretty good banked curve, shortly after a heavy rainfall. My car slid down the mud to the bottom, and I was barely able to get back up and turn around.
So yes, steeply banked curves would allow for higher speeds with a smaller turning radius. But only in good conditions. You'd better hope to God you don't find yourself driving slowly around such a curve on icy roads, or else you're going to be stuck for a while.
I'm sure half of us on this forum could describe a time when our vehicle started to slide on ice while standing still at a complete stop.
Quote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Quote from: kphoger on February 20, 2025, 02:29:56 PMI once drove an unpaved road that had a pretty good banked curve, shortly after a heavy rainfall. My car slid down the mud to the bottom, and I was barely able to get back up and turn around.
So yes, steeply banked curves would allow for higher speeds with a smaller turning radius. But only in good conditions. You'd better hope to God you don't find yourself driving slowly around such a curve on icy roads, or else you're going to be stuck for a while.
Not only the issue with sliding down a steep bankment, but there is also the possibility of rollover for high loads that have a very high center-of-gravity. Many railroads increased Amtrak speeds by increasing the superelevation to 6 inches (as measured from top of the high rail -to- top of low rail, which is over 10.6%). But back then, there was an immediate problem with tall grain railcars flipping over down towards the inside of the curves. So-called "grain trains" were therefore required not to operate between 11 MPH and 17 MPH.
(My understanding is that these situations are no longer considered acceptable, and presumably the superelevation is no longer allowed to be set at 6 inches when such conditions might occur).
Quote from: kphoger on February 20, 2025, 02:29:56 PMI'm sure half of us on this forum could describe a time when our vehicle started to slide on ice while standing still at a complete stop.
Some of us have done while standing still (and not in a vehicle). I've slid down a banked curve more than once, and also had the misfortune of getting out of a car only to lose grip of the door handle, thus sliding down the parking lot more than 200 feet (somehow, I never did fall). :crazy:
Quote from: Dirt Roads on February 20, 2025, 03:03:59 PMMany railroads increased Amtrak speeds by increasing the superelevation to 6 inches (as measured from top of the high rail -to- top of low rail, which is over 10.6%). But back then, there was an immediate problem with tall grain railcars flipping over down towards the inside of the curves. So-called "grain trains" were therefore required not to operate between 11 MPH and 17 MPH.
TIL grain hoppers come in different heights. At first, I thought you might be talking about woodchip gondolas or something, but then I realized "grain trains" most likely referred to unit trains made up of those smooth-sided covered hoppers that are favored for freight-hopping because of the likely presence of a "porch" and covered "cubby" (or, I suppose, there are also unit trains of uncovered hoppers too).
Quote from: Scott5114 on February 20, 2025, 08:27:12 AMQuote from: GaryV on February 20, 2025, 07:41:40 AMMaybe the next technical breakthrough would be a road that senses the speed of the vehicles on it, and increases or decreases the banking of the road to compensate. That way the 150 mph cars could keep going strong, yet grandma on the way to bingo could putter along at her pace.
(where's that sarcasm emoji?)
And if it detects a car without a license plate, it banks up super fast and tosses the car clear into the next county!
Why not helicopters with giant magnets and ... err, never mind ...
Quote from: kphoger on February 20, 2025, 04:14:49 PMQuote from: Dirt Roads on February 20, 2025, 03:03:59 PMMany railroads increased Amtrak speeds by increasing the superelevation to 6 inches (as measured from top of the high rail -to- top of low rail, which is over 10.6%). But back then, there was an immediate problem with tall grain railcars flipping over down towards the inside of the curves. So-called "grain trains" were therefore required not to operate between 11 MPH and 17 MPH.
TIL grain hoppers come in different heights. At first, I thought you might be talking about woodchip gondolas or something, but then I realized "grain trains" most likely referred to unit trains made up of those smooth-sided covered hoppers that are favored for freight-hopping because of the likely presence of a "porch" and covered "cubby" (or, I suppose, there are also unit trains of uncovered hoppers too).
I could also see it potentially being an issue with double-stacked intermodal containers as well.
(https://live.staticflickr.com/65535/54276964928_ed87d3c6eb_z.jpg) (https://flic.kr/p/2qGgCG9)
NS 8098 - NS 288 - Stevenson, AL (https://flic.kr/p/2qGgCG9) by freebrickproductions (https://www.flickr.com/photos/96431468@N06/), on Flickr
Quote from: Scott5114 on February 20, 2025, 06:18:12 AMQuote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Higher superelevation = more dirt work = more expensive
But less land overall
Quote from: kernals12 on February 20, 2025, 06:14:08 PMQuote from: Scott5114 on February 20, 2025, 06:18:12 AMQuote from: kernals12 on February 19, 2025, 10:50:12 PMBut I mean wouldn't a Nascar style curve allow for higher speeds with a smaller turning radius?
Higher superelevation = more dirt work = more expensive
But less land overall
Labor is more expensive than real estate.
Banked curves on freeways are very common.
Here is a modern example of a banked curve on an off-ramp, with a design speed of 65mph. Note that the right parapet of the bridge is pitched slightly higher than the left.
https://maps.app.goo.gl/uv76GhwgyQTxDgT2A?g_st=ac (https://maps.app.goo.gl/uv76GhwgyQTxDgT2A?g_st=ac)
Later on, after merging onto the Interstate from said on-ramp, is this banked curve, build circa 1985.
https://maps.app.goo.gl/hvzjEa2xjC724hEf7?g_st=ac
(https://maps.app.goo.gl/hvzjEa2xjC724hEf7?g_st=ac)
CTH-CV in Madison
https://www.google.com/maps/@43.1685478,-89.3335325,3a,25.2y,267.19h,88.33t/data=!3m7!1e1!3m5!1sD9Jmi1CJhz0nUshHpqKfpg!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fcb_client%3Dmaps_sv.tactile%26w%3D900%26h%3D600%26pitch%3D1.6689949824381216%26panoid%3DD9Jmi1CJhz0nUshHpqKfpg%26yaw%3D267.1915075730727!7i16384!8i8192?entry=ttu&g_ep=EgoyMDI1MDIyNi4xIKXMDSoJLDEwMjExNDUzSAFQAw%3D%3D