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Post by pistonschick on Jun 4, 2010 12:12:25 GMT -8
Hey everyone, I really appreciate the time that everyone has been taking to respond to these requests for input. I am a firm believer that the Yacolt Burn Trails Project is for EVERYONE who wants to experience off-road recreation in SW Washington and that everyone should have an opportunity to weigh in on the decisions that are being made. Every single piece of content in these posts is being carefully read, considered and presented to DNR as we work through designing the bridges, trails and features of this system. The reasoning for the strict rules in the threads and on this forum is that DNR and other intereseted parties are also reading this information, so please remember to keep it clean, stay on topic, try to use internet links or research to support your ideas and above all -- BE NICE . . . With that said, here is the next request: What should be the minimum SAFE turning radius allowance for any potential off-road vehicle approaching or exiting a bridge that can accommodate a 102" wide vehicle?NOTE: This is NOT about trails - only for approach and exit from bridge. Turning Radiusen.wikipedia.org/wiki/Turning_radiusA turn with the turning radius being r.The turning radius or turning circle of a vehicle is the size of the smallest circular turn (ie. U-turn) that the vehicle is capable of making. The term turning radius is actually a misnomer, since the size of a circle is actually its diameter, not its radius. The less ambiguous term turning circle is preferred. As an example, Motor Trend refers to a curb-to-curb turning circle of a 2008 Cadillac CTS as 35.5 feet. By contrast, theAutoChannel.com refers to turning radius of the same car as 35.5 feet. It is often used as a generalized term rather than a numerical figure. For example, a vehicle with a very small turning radius may be described as having a "tight turning radius".As always, I am looking forward to everyone's feedback... Crystal
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Post by ljdude on Jun 4, 2010 16:00:51 GMT -8
I guess that I'm confused about the question. Are you looking to have a wide area at the ends of the bridge to turn around in?
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Post by pistonschick on Jun 4, 2010 16:10:40 GMT -8
Hey Darryl,
I knew that I was struggling to word this correctly - you confirmed that for me.
;D
At each end of the bridge there will be an expected amount of excavation into the bank in order to make a large enough area that a vehicle can make an estimated 90 degree turn either onto or exiting off of the bridge.
So - from each end of the bridge, do we need a 30 foot run-out, 40 foot, 50 foot, 60 foot-- so that all expected vehicles can safely make the exit without damaging their vehicle OR damaging the bridge. The more we need to excavate -- the more it will cost and will play a big part of exactly where the bridge can be located.
I know that my Jeep turns on a dime and I know that my 92' full-size Bronco turned on a dime - I would only need 15-20 feet.
What I am looking for is some feedback from folks with the experience of off-roading vehicles in the large/x-large vehicle category.
Thanks for the question...
Crystal
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Post by bricktop2 on Jun 4, 2010 17:26:39 GMT -8
If I'm missing something, pardon my ignorance, but questions like this or the bridge width questions really aren't items that need to have opinions voiced are they? These are things that have actual solid answers that can be found with a little research. Why would opinions matter when statistics can be produced, backed up by facts? Why not request someone do the research and present their findings? It seems like that would be a much more logical approach. With the facts in hand, the only questions that would remain are:
1. What margin, if any, needs to be added in for the rigs that are completely custom and have no statistics?
2. Should an allowance be made for a trailer behind a rig? If a rig turns sharply enough to make the turn and there is a trailer behind it, what will the result be?
If no allowance is to me made for trailers or customs, you take the widest turning radius out there, factor in the distance the front tires would have to travel in order for the rear tires to clear the bridge, then decide how much to add for driving imperfection, for wider tires and offset wheels, and for bumper overhang depending on the angle of the surface you're turning to avoid since that is not factored into turning radius. If it is virtually straight up and down, you need to look at a wall to wall turning radius instead of a curb to curb turning radius, which can be significantly different. If I get some time over the weekend, I'll try to do some research, get some solid figures and post them up and forward them over to the DNR. Then a decision can be made as to what to do with the margins.
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Post by bricktop2 on Jun 4, 2010 17:31:22 GMT -8
I just read my post and I came across sounding a little critical for some reason. Not intended. Long week. It just seems like a question better answered by research than opinion. Then again, knowing me, I'll get all the facts, accidentally divide some figure instead of multiplying it, and screw the whole thing up so maybe I should just stay away... ;D
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shortbus
Charter Member
Every great day ends in POO!
Posts: 254
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Post by shortbus on Jun 4, 2010 18:15:53 GMT -8
Hey Crystal as you know my subburban is only for towing but I just went out and did a full turn and it was just under 20 foot turn at 90degs turning out of the driveway. Can't imagine that there would be anything longer than that on the trails but you never know. lol
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Post by pistonschick on Jun 4, 2010 18:39:26 GMT -8
I just read my post and I came across sounding a little critical for some reason. Not intended. Long week. It just seems like a question better answered by research than opinion. Then again, knowing me, I'll get all the facts, accidentally divide some figure instead of multiplying it, and screw the whole thing up so maybe I should just stay away... ;D Ok - I'll admit, it rubbed a little - so I took a time-out and came back again. Here's the method to my madness: You're right, I could just do the math and tell DNR what I think. I am pretty confident that I can present a reasonable theory as to what is needed and I am more than capable of providing the research to back up my numbers. BUT, OK, a really BIG BUT, if I do not reach out to the 4x4 community and take into consideration their thoughts on the matter (especially in regards to trail width considerations), I am setting myself up for a formidable public flogging at the end of this project. Also, it would be pretty snarky of me to believe that I can think of everything and every possible scenario all by myself and that I know everything about everything. I know from 22 years of experience that the 4x4 community is worldly wealthy by the way of knowledge, resources and unique ideas about creating and maintaining off-road trail systems - so why not tap into it and at the very same time create a living, breathing document that might help someone else, somewhere else build a trail system in their neck of the woods? Also, we are making every effort to avoid any perceptions of exclusion while making abolutely certain that this project doesn't wind up in a dead end of disagreement - like Reiter for instance... Your input on topics such as this, frees me up to work on things like public relations, fund raising, forest watch patrols, Pick Up the Burn, etc, etc, etc... instead of having to do everything myself. This project would never have left the gate without the members of the club and members of this forum stepping up EVERY SINGLE time I asked for help. So that's it, in a nutshell. I will continue to ask for input. Give it or don't give it - that's your choice, but the record will show -- I ASKED! Crystal
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Post by fivendime on Jun 4, 2010 21:43:47 GMT -8
My opinion here is no more then 30'. If shortbus's suburban can turn in under 20. We all know how long those things are and the one my dad used to have was like driving a small bus around town, lol. Also if you have a trailer, the fact that 4x4 trails weren't meant for a trailer will be evidence enough not to design it for one. not to sound brash or anything but I think we can over engineer something real quick.
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Post by bricktop2 on Jun 4, 2010 21:55:02 GMT -8
I gotcha. I wasn't criticizing your methods, I was questioning the DNR's request for opinions on the matter. I was speaking with them a few weeks ago about the bridge width issue and it seemed like it was pretty cut and dried. Do you want to be able to accommodate the widest rigs out there, or do you want to risk them bypassing the bridge, damaging the area you're trying to protect? Option A. Ok, 102-104 inches to accommodate (barely) a Hummer H1.
I wasn't saying you should be doing this research either, you've obviously got your hands full, I was thinking more along the lines of someone being delegated to do the research to save you some time.
My writing style can be a bit direct at times (my wife reminds me of that from time to time, usually with a 4 letter word or two for emphasis) but I truly don't mean to question your means or methods. I was just voicing my opinions.
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Post by bricktop2 on Jun 4, 2010 21:58:08 GMT -8
My opinion here is no more then 30'. If shortbus's suburban can turn in under 20. We all know how long those things are and the one my dad used to have was like driving a small bus around town, lol. Also if you have a trailer, the fact that 4x4 trails weren't meant for a trailer will be evidence enough not to design it for one. not to sound brash or anything but I think we can over engineer something real quick. True. The trailer thing is probably irrelevant. I wasn't sure if this bridge was on the way to an area where someone might want to camp with a small adventure-style trailer behind a Jeep or something.
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Post by windturbine1 on Jun 5, 2010 5:44:01 GMT -8
i tend to agree with what joey said. my burban would turn really sharp as well. so i think that 30ft would be enough.
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Post by toyrocs on Jun 5, 2010 11:25:13 GMT -8
My comments for turning Radii : a skilled driver can make a "back & fill" maneuver if the situation requires it! Even a rig towing a trailer can back up a little without "jack-knifing" for a real tight turn. I have seen trailers do it on the Rubicon trail to reposition for boulder fields & other tight spots.
IMO the trail width ( distance between trees) is more critical close to a tight radius turn! Part of the challenge is to make these tight turns without backing up! A larger vehicle driver most think ahead ( two or three turns ahead) & position their rig before entering the group of tight and/or restricted width turns.
In regards to tight turns entering & departing a bridge structure. The tendency is for the rear inside tire ( track) to be close to or go over the edge of the bridge in these locations. The radius in these locations are more critical & a larger radius must be used (for safety)" than the minimum set for the trail system. Also a tree or large boulder(s) placed on the inside radius on the bridge approaches, will encourage/ force drivers to stay away from inside radius & position their rig ( line up straight) to safely cross the bridge.
As for an actual turn radius: 22' should work (IMO) . A 22' radius would be 44' curb to curb for the vehicle". This would work fine for almost all rigs & the very largest oversize rigs will just have to " back & fill" if needed.
Toyrocs
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Post by joshwho on Jun 8, 2010 12:23:37 GMT -8
My opinion here is no more then 30'. If shortbus's suburban can turn in under 20. We all know how long those things are and the one my dad used to have was like driving a small bus around town, lol. Also if you have a trailer, the fact that 4x4 trails weren't meant for a trailer will be evidence enough not to design it for one. not to sound brash or anything but I think we can over engineer something real quick. From what I was reading in his post his rig has a 40' turning radius, so that's what I'd say would be a great number if that's the case (on the suburban having a 40' turning radius (which sounds reasonable)). The question was asked based on turning radius, not trying to flame you! I say if your rig can't turn as sharp as a Suburban... back and fill! I don't know of any trail rigs (or rigs straight off the lot for that matter) that cant' turn as "sharp" as a Suburban... just my thoughts! I'm all for having room for fullsizes (seeing as I own a few) and small rigs with high clearance trail trailers, but I like trails to be tight enough that they can offer a challenge.
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Post by fivendime on Jun 8, 2010 14:43:32 GMT -8
My opinion here is no more then 30'. If shortbus's suburban can turn in under 20. We all know how long those things are and the one my dad used to have was like driving a small bus around town, lol. Also if you have a trailer, the fact that 4x4 trails weren't meant for a trailer will be evidence enough not to design it for one. not to sound brash or anything but I think we can over engineer something real quick. From what I was reading in his post his rig has a 40' turning radius, so that's what I'd say would be a great number if that's the case (on the suburban having a 40' turning radius (which sounds reasonable)). The question was asked based on turning radius, not trying to flame you! Dont worry, your not flaming me because I know what I said......30' is what my opinion was not 40'. Depending on where the bridge is put we may not have that space so we might not be lucky enough to have even 30'.
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Post by joshwho on Jun 17, 2010 14:36:35 GMT -8
Yeah, now that I know what the issue is with turning sharp off the end of a bridge (needing to climb out of a canyon INSTANTLY) I say go 30' or less. People can back if they need to... if there's no other place to put the thing, that'll have to work!
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