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Post by pistonschick on May 19, 2010 16:15:46 GMT -8
Hey guys and gals,
We are starting to make some final determinations and recommendations to DNR as to what the Yacolt Burn trail system is going to look like. For this first task, I am needing feedback from ACTIVE 4x4 enthusiasts. It does not matter if you wheel a Jeep, a stock Toyota, a Full-Size Truck or a custom-fab buggy - your input matters to us...
First and foremost, we need to make some decisions about a required water crossing that will be mandatory in the first phase of the trail system. This will be in the form of an approximately 85 foot long bridge. We are not looking for material or design recommendations - those decisions will lie within the design engineer's responsibilities.
What we are looking for from all of you out there is how wide should the bridge be built? This bridge will accommodate 4x4's, Side-by-Sides, ATV's and Dirtbikes. In the spirit of equal opportunity as well as fiscal responsibility, we are looking to design a bridge that will accomodate the largest realistic 4x4 that might be utilizing the bridge today (and in the future) while still keeping it small enough to avoid pricing ourselves right out of this trail opportunity.
SO - the two primary things we need to determine:
1) How wide should the bridge be?
2) What weight capacity should the bridge be built to?
Some things you should consider before responding:
1) What is the maximum width of existing 4x4's that are currently responsibly recreating in the forests in the Pacific Northwest?
2) What is the maximum width of the vehicles that you and your fellow 4-wheelers are currently wheeling?
3) What is the maximum weight (including passengers & gear) of 4x4's that are currently responsibly recreating in the forests in the Pacific Northwest?
4) What is the maximum weight (including passengers & gear) of the vehicles that you and your fellow 4-wheelers are currently wheeling?
5) This bridge will be around for a LONG, LONG time - what sizes of 4x4's do you think we will all be driving in 10 years? 20 years? 30 years? 40 years? How about 50 years? Will they be larger? or smaller?
Some more things to consider:
(the following numbers are rough estimates based on previous bridges built on DNR lands - this is only to help assist you in your recommendations for bridge size):
A 85 foot ATV bridge (60" wide), able to accommodate up to ten (10) ATV's (with passengers and gear) at one time will cost in the neighborhood of $75,000.
A 85 foot bridge (10 feet wide) built to handle one (1) loaded log truck at a time will cost in the neighborhood of $150,000.
Obviously, we will fall somewhere in between the two samples listed above. The question is where?
Basic algebra gives us an estimate that an 85 foot bridge (7 1/2 feet or 90" wide) built to handle five (5) 4x4's at one time might fall into the $112,500 range. OR another way to look at it - each additional inch in width equals another $1,250 added to the total bill...
One last thing to consider - even though most of us cross bridges on off-road trails only one or two vehicles at a time, we need to plan for the worst possible scenario (ie) how many of the heaviest 4x4's will fit on an 85 foot long bridge?
I will try to answer any and all questions in this thread, but I will not tolerate ANY attacks on other users posts - EVERYONE has a right to weigh in on this decision and we will do our very best to make certain that the DNR staff considers all ideas submitted here.
If you want your input considered, but do not wish to post it on the public forum, please PM it to me and I will post it in this thread anonymously.
Thank you in advance for everyone's input and consideration, we look forward to receiving your feedback.
Kind regards,
Crystal Crowder Club President Piston's Wild Motorsports (360) 606-1648
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Post by fivendime on May 19, 2010 17:49:12 GMT -8
Take for instance the earliest form for off road recreating for allot of people. The old Willys CJ2A. I know that my CJ3B is about 66" wide and weighs probably around 4000 lbs max with gear though Ive never weighed it. Now days we have mostly Wranglers, Toyota pickups, Cherokees, and a few other rigs that are the main 4x4's used. Most of them no more wider then 76" at best and 13' long nose to tail. Most of them also weight in at around 4000 lbs with gear. I think the weight can honestly be based on that number of 4000 lbs. as an average. I think since the old willys has been around for 50 in my opinion it would be safe to say that whatever is around in the future is and almost certainly will be lighter weight, but stay the same size because 104" wheel base seems like a very popular number. Full size is also considered here.
Here are my numbers for width and vehicle weight Width would be around 90 inches and no more. Weight based on 6 rigs at 13' long which would equal 24,000 lbs.
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Post by racincowboy on May 19, 2010 19:13:00 GMT -8
With all vehicles being considered I would build the bridge to withstand the heaviest and widest vehicles. With that said the smaller and lighter vehicles will have no problem.
1) I myself I wheel a wrangler Tj. Now with that being said I know there are guys out there wheeling everything from a Suzuki Samurai to full size trucks that are big and wide. I would think that that 90" max width would suffice in my opinion.
2) As far as weight bearing goes I would say Joey is right on. I have never weighed my jeep fully loaded either but I would venture to say it is somewhere between 4-5k being on the generous side. I would venture to say a full size could range upwards of 6500 also being on the generous side of weight. My personal thought is I would say distance wise I would go with the average length being around 14 feet each. Some will be longer some shorter.
So just as an example (that I have never seen happen) lets say 6 rigs @14 feet long at 5k each would end up taking up 84 Feet of bridge and weigh 30,000 lbs. This being all rigs nose to tail on bridge. This being worst case senario.
As far as approach angle I would say the rigs using this bridge would be able to handle a 15 degree approach angle safely no problem.
In the future I think the rigs will stay relatively the same size or smaller then they are now. I think that would be a safe bet.
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Post by bricktop2 on May 19, 2010 19:16:05 GMT -8
What will the sides be like? There are a lot of 80" wide rigs out there. If the plan is to secure some rails on the top edges to provide a form of curb, assuming they're 4" wide each, a 90" wide bridge is now 82", leaving only an inch per side to play with for a JK with wider stance wheels. Jeeps of the future sure wont be getting any narrower.
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Post by toyrocs on May 19, 2010 19:29:13 GMT -8
My rig is; A. 1) 96" wide. 2) 14' 2" long. 3) 117" wheelbase. 4) 6,100 lbs ( winter) 5,700 lbs ( summer). B. Bridge should be 102" wide ( normal max allowable width for road vehicles in WA state). This will accommodate all vehicles now & in the future. Search & rescue vehicles will be able cross a wide 102" bridge! This 102" wide bridge will also allow trail maintenance vehicles to maintain the trail ( tractors, backhoes, excavators, gravel trucks etc). Another benefit of a 102" wide bridge is user safety! A wider bridge provides more room for driver error! Total average 4x4 vehicle length : 14' ( assumption) Clearance distance between parked 4x4 vehicles on bridge ( bumper to bumper): 2'ea . :-/Drivers of vehicles that are WIDER than the bridge, will attempt to cross a narrow bridge. This condition is hazardous to users & will damage the bridge. :oThis exact scenario has happen on a bridge I believe on DNR lands in the Elbe Hills area 5- 10 years ago!! C) 4 Total 4X4 Vehicles on bridge with 2' bumper to bumper clearance ( between vehicles. total length= 62 5 total 4X4 vehicles on bridge with 2' clearance between, total length=78' Length of planned bridge assume 85' Weight of each vehicle ( approx.)= 6,000 lbs Number of vehicles on bridge at one time= 5 D) Total worst case weight= 30,000 lbs with load evenly spread over entire span. I would personally NEVER drive/ park 5 ( five) 4x4 vehicles on this sort of proposed bridge. There is a forest river crossing 4x4 bridge on the Rubicon trail in CA. My guess it has a span of 60' between piers with about 15' ramps from piers to ground on each end . Total Length of about 90'. The maximum number of 4x4's I have ever seen on this 4x4 bridge at the same time has been 3. One on entrance ramp, one mid span & one on exit ramp. I would have a maximum of 3 4x4 rigs on the proposed DNR bridge at the same time. E) With the above givens (3 rig @ 6,000 lbs ea.). Total weight on bridge= 18,000 lbs. I assume that the DNR could also post /limit weight of vehicles on bridge at same time.This would be similar to what ODOT/ WDOT does now on restricted weight/ single lane bridges around the state! My long range expectation for 4x4 vehicles in the future: most vehicles are now at their maximum weights & we will see a decrease in weight into the future. Fuel economy/ green house gas emissions/ better performance with lighter weights will drive this weight reduction. Widths will continue to increase due to safety & performance gains for most types of motorized recreational users. This width increase is also evident in many cars/ light trucks of the last decade. Most vehicles get wider / longer over the model generation changes. Toyrocs
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Post by windturbine1 on May 19, 2010 19:48:06 GMT -8
i tend to agree with toyrocs. while right now i have a cherokee, i am looking for another dodge ramcharger. my last one weighed in around 6500. although it did have alot of stuff on it my next wont. just my 2 cents.
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Post by pistonschick on May 19, 2010 20:11:41 GMT -8
What will the sides be like? There are a lot of 80" wide rigs out there. If the plan is to secure some rails on the top edges to provide a form of curb, assuming they're 4" wide each, a 90" wide bridge is now 82", leaving only an inch per side to play with for a JK with wider stance wheels. Jeeps of the future sure wont be getting any narrower. Hey Brian, Thanks for chiming in - your input is greatly appreciated. We will go ahead and leave the "design" of the rails to the engineer. With that said, I am looking for the maximum recommended width of the bridge "inside rail to inside rail". Or, what is the widest vehicle that can be accommodated by the bridge... Crystal
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Wyldman
Active Member
Safety & Education Chairman
IXOYE
Posts: 643
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Post by Wyldman on May 19, 2010 21:17:39 GMT -8
The most important thing to take into consideration is... Will Fire and Rescue vehicles need to use the bridge? I can assure you that if a forest fire is ablaze in the area and this bridge is the only access to the fire, your going to need to build a bridge to accommodate the largest fire truck and rescue vehicles the locale departments use. All things else are secondary. If that is not the case, then a width of about 102" to 104" and it should be able to withstand 25,000 to 30,000 lbs.
Hope this Helps,
Douglas
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Post by oltmann on May 20, 2010 6:27:36 GMT -8
Is this bridge going to have an 85' unsupported span?
I'll throw in with Toyrocs and Wyldman on this. Enough capacity for emergency and trail maintenance vehicles. 104" and 15-20 tons sounds about right.
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Post by fivendime on May 20, 2010 7:02:10 GMT -8
A few questions I have before I agree with the maintenance/emergency vehicles using it. Are they even going to be able to make it to the bridge? Meaning, there would be little point in making the bridge capable of use buy a rig that wide if they cant even make it there in the first place. The idea is a good one but I believe that question needs to be answered first. One other idea. If the bridge has rails on the side that's good, but if not to keep wider rigs from using it would be easy to eliminate using steel poles on each end as a width filter. Going from 90" to 104" would cost us another 17,500 bucks. If those emergency rigs can get to the other side just as easily from another entry point from a gravel road (meaning reasonable distance traveled) then there would be no reason for it being that wide. I would safely assume that if it were a serious issue DNR would mandate that we have it that wide.
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Post by toyrocs on May 20, 2010 7:29:19 GMT -8
I have also seen previously owned flatbed Railroad cars used as a bridge. These are of the correct width/ Length & more than enough weight carrying capacity to meet the requirements. The heavy loads & "span" engineering have already been done & the cars are available on the used market. These make great off-road bridges like the one needed for this DNR project! Can the DNR buy off on ( agree) to use a bridge like this? Transport to job site? Via the trail system?. I also know of at least one bridge like this that was transported by a heavy lift helicopter directly to job site & positioned in place. Costs? SEE RESEARCH & DESIGN REVIEW FOR USE OF RAILCARS FOR LOW VOLUME/ LOW COST ROAD BRIDGES (BELOW). www.iowadot.gov/operationsresearch/reports/reports_pdf/hr_and_tr/reports/tr421.pdfToyrocs
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Post by bricktop2 on May 20, 2010 11:47:56 GMT -8
...I would safely assume that if it were a serious issue DNR would mandate that we have it that wide. x2. I think they're going to do what they need to do for emergency vehicles if they will indeed need access which will effectively render our opinions unnecessary. Crystal, you're right. The real question should be what is the width of the vehicles, not how wide should the bridge be. Without knowing the exact design and how much usable surface area there will be, the bridge's width is irrelevant. fwiw, 104" would cover Hummers as well. If I were building it, that's what I'd go with. Having a great relationship with the DNR is a good thing, and it won't take many instances of some yahoo in a Hummer not fitting and deciding to bypass it, tearing up 85 feet of protected watershed or wetlands, to create some bad vibes.
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Post by toyrocs on May 20, 2010 12:04:24 GMT -8
Another thought on Bridge Design/ materials. Vandalism. Wood bridges have been/ are a target for arson. Steel bridges ( like a rail car) have a high resistance to such illegal activities & are less of a magnate for arson/ & other vandalism.
Toyrocs.
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Post by pistonschick on May 20, 2010 13:12:47 GMT -8
All of these posts are awesome - please keep em' coming...
I will be away from a computer for the next 4 days and unable to answer any questions until Monday evening, May 24th.
Fivendime - please monitor this thread over the weekend for me to ensure that everyone has a safe place to voice their thoughts on the issue.
I will ensure that everyone's opinions are presented to DNR in a fair and equal manner.
Please remember that we are discussing the width and capacity of ONE bridge in ONE section of ONE forest. This will not be the end all, be all, determination of all bridges and WILL NOT dictate the final determination of the width of trails in the Yacolt Burn. I will open that can of worms for another discussion, at another time...
Please continue with the discussion of the questions as they have been presented in the first thread. Keeping this thread on track is key to being able to present useful information to DNR that can be appropriately applied to the project as it progresses.
Thank you again to everyone for your input, I look forward to reading more when I get back to the computer on Monday...
Crystal
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Post by toyrocs on May 20, 2010 15:39:48 GMT -8
Do we actually need a traditional bridge? Can some other form of structure, fulfill the same function? Bridges are a way to get from one point to another point. Usually spanning an obstruction below. Like a roadway overpass/ underpass, or creek/ river/ canyon. How about a concrete " bridge" ? By this I mean a concrete structure that is on the bottom of a stream/ creek bed. All the water flows over the concrete & vehicles drive on the concrete across the creek. The vehicle tires do not touch the stream beds natural surface. This sort of " bridge" does not "dam up" or hold water behind it. This type of bridge will not restrict fish movement across the bridge area.
This type of concrete bridge has been in use by the US BLM in various locations for decades. These bridges are used by motorcycles, ATV's,4x4's, heavy construction vehicles & even 2wd cars ! Super low maintenance, low user risk, easy to engineer/ build. I can't think of a cheaper solution, if this type of bridge will work for the proposed DNR trail location.
I have personally used these types of bridges ( on BLM lands) with M/C's & 4x4's with no problems. No stalled out vehicles due to wet ignitions etc with normal crossing speeds. The water depth flowing over the bridge is usually not critical, but would have to be calculated for a specific site/ water flow conditions . The wider the bridge the lower the depth of water flowing over it, would be a general engineering rule for these. Most stock 2wd vehicles have no problem with water depths of 8" or so, let alone M/C, ATV's & lifted 4x4's that can easily handle over two feet or more!
Hardened bridges like the above are used on many 4x4 trails in the west. Some use constrained rocks instead of concrete as the bridge material. A metal mesh " enclosure", that is full of rocks/ small boulders are used . The mesh enclosure used is similar too chain link fence material. These are also similar to the rockfall ( avalanche control) rock fences that protect cars. These types of meshes are used by WDOT on some of the Highway Mountain passes. The rock filled bridges are also used by the Tahoe National Forest as ATV /4x4 bridges , on the eastern part of the Rubicon trail. They have been durable & effective as an environmentally sound bridge.
Toyrocs
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