|
|
|
|
MechEngDropout
Member
|
|
|
Joined: 27 Jun 2003
Posts: 10474
Location: Off the grid
|
| Back to top
|
|
 Posted: 09/26/04 - 10:55 Post subject: Highway Construction
While driving in unfamiliar territory last night, I noticed something odd about the interstate junction. I was on Highway 61 south, crossing I-10. Now normally there would be 2 exits, one for I-10 east, and one for I-10 west. Heading south, the west exit would come first and would just be a right turn then merge onto the interstate. The east exit would normally be a cloverleaf. Now for this junction, they didn't have a west exit, just an east one. The east exit goes under the interstate then on an overpass above Hwy 61, then merges onto the interstate. Heading north on 61 has the same oddity. No east exit, and the west exit goes over the interstate and over 61, then merges with the interstate.
What's the point of that? If you're only going to have one exit for each direction, why wouldn't you make it the one that is easier to construct? Why not have a west exit from 61 south and an east exit from 61 north? No overpasses necessary, same basic traffic flow. Anyone?
|
|
|
|
|
Ms. Jenn
Fresh, Hot & Wild
|
|
|
Joined: 14 Feb 2004
Posts: 7935
Location: Suite 550
|
| Back to top
|
|
Posted: 09/26/04 - 11:11 Post subject:
If I'm reading your description right, they are called high speed interchanges. You can keep a relatively high speed while merging onto the new road, whereas in a cloverleaf design you have to slow down to at least 30 to make the sharp turn.
Cloverleaf designs are very dangerous and most highway departments are phasing them out as road improvements occur.
Right of way is usually the biggest hurdle in road construction (acquiring enough space to build a proper section). Second being drainage.
|
|
|
|
|
MechEngDropout
Member
|
|
|
Joined: 27 Jun 2003
Posts: 10474
Location: Off the grid
|
| Back to top
|
|
Posted: 09/26/04 - 11:21 Post subject:
Maybe this will clear it up:
In blue are the current ramps. I'm wondering why it wouldn't be something like what I added in red. It's the same basic concept; one exit in each direction, yet you would minimize building materials and the complexity of overpasses.
|
|
|
|
|
JACKED UP
PRESIDENT
|
|
|
Joined: 06 Jun 2003
Posts: 21238
Location: www.johnnydu.com
|
| Back to top
|
|
Posted: 09/26/04 - 11:22 Post subject:
I'm sorry MED, I'm not even gonna try to figure that out. Just reading that makes my panic button go off. 
|
|
|
|
|
Ms. Jenn
Fresh, Hot & Wild
|
|
|
Joined: 14 Feb 2004
Posts: 7935
Location: Suite 550
|
| Back to top
|
|
Posted: 09/26/04 - 12:41 Post subject:
In this particular case, I would bet it's because of the rail line.
The high speed interchanges (which include the overpass design) does not affect the rail line in any way.
|
|
|
|
|
MechEngDropout
Member
|
|
|
Joined: 27 Jun 2003
Posts: 10474
Location: Off the grid
|
| Back to top
|
|
Posted: 09/26/04 - 12:45 Post subject:
| Ms. Jenn wrote: | In this particular case, I would bet it's because of the rail line.
The high speed interchanges (which include the overpass design) does not affect the rail line in any way. |
Perhaps. Maybe I'll research it.
But maybe not.
|
|
|
|
|
Ms. Jenn
Fresh, Hot & Wild
|
|
|
Joined: 14 Feb 2004
Posts: 7935
Location: Suite 550
|
| Back to top
|
|
Posted: 09/26/04 - 12:51 Post subject:
There also might be a grade/soils/environmental impact issues with the other design.
|
|
|
|
