Braindead Engineers
Senior Member
Joined: Jan 2000
Posts: 398
Likes: 0
From: Hawaii
BlueFlareside:
I just sent you an e-mail. Was the graphic you posted created with MicroStation or if not, what program was used?
george:
in a heartbeat!! I've been here waaayyy too long. Rock fever and all that ...... !!!
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'00 5.4L AUTO 4X4 F-150 Lariat
'98 4.0L 5spd Jeep Wrangler Sport
'02 F-350 PSD CC DRW 6SPD 4X4 Lariat (order this year)
www.hawthorn-engineering.com
I just sent you an e-mail. Was the graphic you posted created with MicroStation or if not, what program was used?
george:
in a heartbeat!! I've been here waaayyy too long. Rock fever and all that ...... !!!
------------------
'00 5.4L AUTO 4X4 F-150 Lariat
'98 4.0L 5spd Jeep Wrangler Sport
'02 F-350 PSD CC DRW 6SPD 4X4 Lariat (order this year)
www.hawthorn-engineering.com
Member
Joined: Jun 2001
Posts: 34
Likes: 0
From: Austin, TX
Blueflareside,
Where at outside of Austin is this road supposed to take place? I know that they are jacking up the lower deck as we speak but I didn't know they really wanted more of that kind of lower/upper deck design.
Oh wait, is that for the new highway that will bypass Austin completely? New highway 30 or something like that?
Where at outside of Austin is this road supposed to take place? I know that they are jacking up the lower deck as we speak but I didn't know they really wanted more of that kind of lower/upper deck design.
Oh wait, is that for the new highway that will bypass Austin completely? New highway 30 or something like that?
Senior Member
Joined: Jan 2000
Posts: 2,075
Likes: 1
From: Central Florida
That picture is of SH45. It is a toll road for the Texas Turnpike Authority. It is on the North side of Austin. Our section goes from I-35 to the East for a couple of miles. I think it is part of an outer loop but I was not involved enough to know all of the details. I flew out a couple of times last year and finished up working on it about 6 months ago. I know they are constructing the WB frontage road for the Dell facility right now.
[This message has been edited by BlueFlareside (edited 06-25-2001).]
[This message has been edited by BlueFlareside (edited 06-25-2001).]
Senior Member
Joined: Jul 2000
Posts: 5,116
Likes: 3
From: Houston, by way of every major city in America.
I've got a question for the CE's. On ground level highway entrance ramps that follow a circular pattern,why do they put the sharpest part of the curve nearest to the highway? I've noticed this alot as I travel all over the country. You trying to get your speed up to enter the highway,then you have to drop your speed right when you need it the most. Just seems strange to me 
,,,,98
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98 F-150 4.6 Litre XLT 4x2 Ext. cab
prarie tan/tan int.
Yep,it has alot of stuff installed on it,I just got sick of lugging that huge sig. around,hehe
Come and see my newest pictures@ www.my-f150.com
Everything is shown there,except for the Superchip,Thanks Mike T!!
FENDER GUITARS ROCK!!!
Now,if it only looked like this in real life
,,,,98------------------
98 F-150 4.6 Litre XLT 4x2 Ext. cab
prarie tan/tan int.
Yep,it has alot of stuff installed on it,I just got sick of lugging that huge sig. around,hehe
Come and see my newest pictures@ www.my-f150.com
Everything is shown there,except for the Superchip,Thanks Mike T!!
FENDER GUITARS ROCK!!!
Now,if it only looked like this in real life
Senior Member
Joined: Jan 2000
Posts: 2,075
Likes: 1
From: Central Florida
98SCREAMER,
I know where you mean but most loop ramps are either the same radius all of the way around or they are made up of three compund curves. There are tow larger radius curves at the beginning and end of the curves. I have not noticed any around here that are that way.
One thing that may make it seem like it is sharper is that the curve is superelvated until the end of the curve (and the beginning). Towards the end we create a superelevation transition to the tangent (straight) section. Say the curve is at a 9% superelevation and the mainline that it is tying into is at 2%, it would take a few hundred feet to transition the super out of the curve.
The key to a good design is to have a long enough acceleration lane before you have to merge onto the mainline. This will let you get up to the speed of traffic on the mainline from the ramp.
I know where you mean but most loop ramps are either the same radius all of the way around or they are made up of three compund curves. There are tow larger radius curves at the beginning and end of the curves. I have not noticed any around here that are that way.
One thing that may make it seem like it is sharper is that the curve is superelvated until the end of the curve (and the beginning). Towards the end we create a superelevation transition to the tangent (straight) section. Say the curve is at a 9% superelevation and the mainline that it is tying into is at 2%, it would take a few hundred feet to transition the super out of the curve.
The key to a good design is to have a long enough acceleration lane before you have to merge onto the mainline. This will let you get up to the speed of traffic on the mainline from the ramp.
Senior Member
Joined: Mar 2000
Posts: 685
Likes: 0
From: Cincinnati, Ohio
What you are referring to is a spiral curve. It is a constantly decreasing radius curve with constantly increasing degree of curvature. They are really only used on highways, and were originally used for railroads. I have never designed Interstates so I can't really tell you a whole lot more.
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2000 F150 XLT 4x4 Short Bed. Amazon Green, 5.4L, SuperCab, ORP, Tow Package, Sliding Rear Window, Electronic Shift, Remote Keyless Entry, LT265-70-17 Tires, Clarion Pro Audio, Herculiner Bedliner, Air Silencer Removed, Keyless Entry Mod
1994 SVT Mustang Cobra. #1032 of 5009.
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2000 F150 XLT 4x4 Short Bed. Amazon Green, 5.4L, SuperCab, ORP, Tow Package, Sliding Rear Window, Electronic Shift, Remote Keyless Entry, LT265-70-17 Tires, Clarion Pro Audio, Herculiner Bedliner, Air Silencer Removed, Keyless Entry Mod
1994 SVT Mustang Cobra. #1032 of 5009.
<A HREF="http://home.fuse.net/94cobra/my150.html" TARGET=_blank>
</A>
Senior Member
Joined: Jan 2000
Posts: 2,075
Likes: 1
From: Central Florida
2000 F150 4x4,
Spirals are used in quite a few states but we do not use them much here in Florida. Here is a definition from a textbook:
Generally, the Euler spiral, which is also known as the clothoid, is used. The degree of curve varies from zero at the tangent end of the spiral to the degree of the circular arc at the circular curve end.
Any motor vehicle follows a transition path as it enters ir leaves a circular horizontal curve. The steering change and the consequent gain or loss of centrifugal force cannot be effected instantly. For most curves the average driver can effect a suitable transistion path within the limits of normal lane width. However, with combinations of high speed and sharp curvature the resultant longer transition can result in crowding and sometimes actual occupation of adjoining lanes. In such instances spiral curves would be appropriate because they make it easier for a driver to confine his vehicle to his own lane. A properly design spiral transition curve provides a natural easy-to-follow path for drivers, such that the centrifugal force increses and decreases gradually as a vehicle enters and leaves a circular curve.
Spirals are used in quite a few states but we do not use them much here in Florida. Here is a definition from a textbook:
Generally, the Euler spiral, which is also known as the clothoid, is used. The degree of curve varies from zero at the tangent end of the spiral to the degree of the circular arc at the circular curve end.
Any motor vehicle follows a transition path as it enters ir leaves a circular horizontal curve. The steering change and the consequent gain or loss of centrifugal force cannot be effected instantly. For most curves the average driver can effect a suitable transistion path within the limits of normal lane width. However, with combinations of high speed and sharp curvature the resultant longer transition can result in crowding and sometimes actual occupation of adjoining lanes. In such instances spiral curves would be appropriate because they make it easier for a driver to confine his vehicle to his own lane. A properly design spiral transition curve provides a natural easy-to-follow path for drivers, such that the centrifugal force increses and decreases gradually as a vehicle enters and leaves a circular curve.
