Interstate standards

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Bradley Torr

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Nov 2, 1999, 3:00:00 AM11/2/99
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Hello,

Is there a webpage somewhere out there - official or not - which lists the
technical standards needed for a road to be considered 'interstate grade'?

Regards,

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Bradley S. Torr - Geographic Information Systems student
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Australian Highways Page - http://www.users.bigpond.com/btorr/ausroads


John Lansford

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Nov 2, 1999, 3:00:00 AM11/2/99
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"Bradley Torr" <bt...@bigpond.nospam.com> wrote:

>Hello,
>
>Is there a webpage somewhere out there - official or not - which lists the
>technical standards needed for a road to be considered 'interstate grade'?

FHWA might have something, or AASHTO.

The standards aren't that much more stringent than for a good freeway,
though. For a road to be designed as an interstate (or signed as one),
it must:

1) Have a design speed of 60mph or higher
2) Have a median of 22' or wider
3) Have 10' outside paved shoulders, 2' inside shoulders (minimum)
4) Have at least two lanes in each direction separated by a median
5) At least 15'6" vertical clearance for any overhead structures
6) Controlled access with interchanges and grade separations
7) Horizontal clearances of at least 10' on either side of the lanes
8) A new requirement is guardrail in all medians <60' in width

FHWA requires design exceptions for any of these features that are not
met. Some of the criteria MUST be followed, though, such as the
controlled access criteria and the minimal median width. If too many
exceptions are present on any one project, though, FHWA will require
all of them to be upgraded before allowing the road to be signed/built
as an interstate.

John Lansford, PE

The unofficial I-26 Construction Webpage:
http://users.vnet.net/lansford/a10/

SPUI

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Nov 2, 1999, 3:00:00 AM11/2/99
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For example, I-10 in Texas and I-180 in Wyoming :)

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John Lansford <jo...@vnet.net> wrote in message
news:nHAfOKev2cKdWh...@4ax.com...

Nathan Perry

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Nov 3, 1999, 3:00:00 AM11/3/99
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In article <2gLd0VHzLOdZ-pn2-pZw6EYBobeGu@localhost>, gren...@uiuc.edu
(David J. Greenberger) wrote:

> Okay, which Interstates are the worst violators? I'll nominate the BQE
> (I-278) -- it meets requirements 4, 6, and 8(!) and fails the other five.
> (Shoulders? Horizontal clearance? Ha! Let's put a brick wall directly
> up against the right lane!)

I-93; hence my revocation of its number.

1) Have a design speed of 60mph or higher

Occassionally...

2) Have a median of 22' or wider

Rarely.

3) Have 10' outside paved shoulders, 2' inside shoulders (minimum)

What's a shoulder?

4) Have at least two lanes in each direction separated by a median

That's one condition met.

5) At least 15'6" vertical clearance for any overhead structures

Never took out the tape measure but I think it wins.

6) Controlled access with interchanges and grade separations

The word "controlled" may be too strong here.

7) Horizontal clearances of at least 10' on either side of the lanes

Including or not including broken-down vehicles, state troopers, and backhoes?

8) A new requirement is guardrail in all medians <60' in width

We can grandfather it out of that one. As you can see, a pretty low score.

Also: an interstate must have shoulders, but must they be used exclusively
for non-driving activities? The right shoulder of some parts of I-95 are
used as lanes during rush hour, except by exiting traffic which uses the
far rightmost of the regular lane. (Horrors!)

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Brandon M. Gorte

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Nov 3, 1999, 3:00:00 AM11/3/99
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John Lansford <jo...@vnet.net> wrote:
: "Bradley Torr" <bt...@bigpond.nospam.com> wrote:

: >Hello,
: >
: >Is there a webpage somewhere out there - official or not - which lists the
: >technical standards needed for a road to be considered 'interstate grade'?

: FHWA might have something, or AASHTO.

: The standards aren't that much more stringent than for a good freeway,
: though. For a road to be designed as an interstate (or signed as one),
: it must:

I'll take on the Borman Expy (I-80/94/US-6) in NW Indiana here:

: 1) Have a design speed of 60mph or higher

Supposedly. However traffic dictates the speed, along with the potholes.

: 2) Have a median of 22' or wider

Might just make it. Just a jersey barrier and two 8-10 foot shoulders.

That is, if shoulders are a part of the median. If not, nope.

: 3) Have 10' outside paved shoulders, 2' inside shoulders (minimum)

Meets it, even if they are potholed and cratered.

: 4) Have at least two lanes in each direction separated by a median

Three per direction, but vastly overwhelmed by the amount of traffic.

: 5) At least 15'6" vertical clearance for any overhead structures

Not on some of the arched bridges. The right and left lanes tend to
violate this, but the center lane is 16'+.

: 6) Controlled access with interchanges and grade separations

Yes.

: 7) Horizontal clearances of at least 10' on either side of the lanes

Not with the signage and lighting. Some of the bridges are awlfully close
too.

: 8) A new requirement is guardrail in all medians <60' in width

It has a jersey barrier. A low jersey barrier (not the newer ontario
barrier).

Brandon Gorte
Undergrad in Geological Engineering
Michigan Technological University, Houghton, MI
<http://www.geo.mtu.edu/~bmgorte/freeway.html>


John Lansford

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Nov 3, 1999, 3:00:00 AM11/3/99
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gren...@uiuc.edu (David J. Greenberger) wrote:

>On Tue, 2 Nov 1999 23:23:52, John Lansford <jo...@vnet.net> wrote:
>
>> 2) Have a median of 22' or wider
>

>Does the presence of a Jersey barrier reduce this number?

No. 22' is the minimum median width, and a Jersey barrier doesn't
reduce this any further.

> If not, I'd
>guess quite a few urban Interstates are in violation, including I-74
>through Champaign-Urbana.

Lots of old interstates have narrower medians than 22'. Exceptions are
required for these violations of the standards (they aren't that hard
to get either).

John Lansford

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Nov 3, 1999, 3:00:00 AM11/3/99
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nwp...@student.berklee.edu (Nathan Perry) wrote:


>Also: an interstate must have shoulders, but must they be used exclusively
>for non-driving activities? The right shoulder of some parts of I-95 are
>used as lanes during rush hour, except by exiting traffic which uses the
>far rightmost of the regular lane. (Horrors!)

FHWA and AASHTO strongly discourage this kind of official sanction to
use the paved shoulder as a lane. If it is done by drivers without any
kind of approval by the DOT, there's little that can be done about it.


Personally, someone else can seal any project of mine where I am told
to design the road for traffic use of the shoulder. I refuse to allow
such a practice to be put into operation on one of my projects.

John Lansford

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Nov 3, 1999, 3:00:00 AM11/3/99
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Brandon M. Gorte <bmg...@mtu.edu> wrote:

>John Lansford <jo...@vnet.net> wrote:

>I'll take on the Borman Expy (I-80/94/US-6) in NW Indiana here:
>
>: 1) Have a design speed of 60mph or higher
>
>Supposedly. However traffic dictates the speed, along with the potholes.

Traffic speed has nothing to do with the design speed. Neither does
the lack of maintenance.

>: 2) Have a median of 22' or wider
>
>Might just make it. Just a jersey barrier and two 8-10 foot shoulders.

That's the idea. 22' gives you room for the barrier (about 2' wide)
and two 10' shoulders.

>That is, if shoulders are a part of the median. If not, nope.

Of course they are. A median is defined as everything between the
inside edge of the travel lanes.

>: 3) Have 10' outside paved shoulders, 2' inside shoulders (minimum)
>
>Meets it, even if they are potholed and cratered.
>
>: 4) Have at least two lanes in each direction separated by a median
>
>Three per direction, but vastly overwhelmed by the amount of traffic.

Doesn't matter.

>: 5) At least 15'6" vertical clearance for any overhead structures
>
>Not on some of the arched bridges. The right and left lanes tend to
>violate this, but the center lane is 16'+.
>
>: 6) Controlled access with interchanges and grade separations
>
>Yes.
>
>: 7) Horizontal clearances of at least 10' on either side of the lanes
>
>Not with the signage and lighting. Some of the bridges are awlfully close
>too.

Many older bridges do not meet this standard. It used to be a 2'
clearance, which is all a lot of the older structures has, even on the
right side.

>: 8) A new requirement is guardrail in all medians <60' in width
>
>It has a jersey barrier. A low jersey barrier (not the newer ontario
>barrier).

Sounds like a typical older interstate to me.

Bradley Torr

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Nov 3, 1999, 3:00:00 AM11/3/99
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John Lansford <jo...@vnet.net> wrote in article
<BRMgOHNezrOohv=Ws8gFS...@4ax.com>...

> No. 22' is the minimum median width, and a Jersey barrier doesn't
> reduce this any further.

What about bridges? Must the two directions on a bridge be separated by
22', or would a Jersey barrier or a low concrete median suffice in this
case?

Also, are there minimum ramp lengths, radii of loops and ramps etc. on
interchanges necessary to meet Interstate criteria?Or would these be the
same as for any other freeway (for which definitons vary between states
IIRC?)

Regards,
Bradley.


John Lansford

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Nov 3, 1999, 3:00:00 AM11/3/99
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"Bradley Torr" <bt...@bigpond.nospam.com> wrote:

>
>John Lansford <jo...@vnet.net> wrote in article
><BRMgOHNezrOohv=Ws8gFS...@4ax.com>...
>
>> No. 22' is the minimum median width, and a Jersey barrier doesn't
>> reduce this any further.
>
>What about bridges? Must the two directions on a bridge be separated by
>22', or would a Jersey barrier or a low concrete median suffice in this
>case?

Well, if you've got a 22' median, it's probably cheaper to build one
bridge and run the median across the structure instead of building two
separate ones.

If for some reason two bridges were built using a 22' median, the
bridges themselves don't have to be 22' apart. You'd still have to
have the proper horizontal clearances, though.

>Also, are there minimum ramp lengths, radii of loops and ramps etc. on
>interchanges necessary to meet Interstate criteria?

Certainly. These are all built into the minimum 60mph design speed,
though. There are minimum radii for loops, but this is a practical
design criteria and not limited to interstates.

>Or would these be the
>same as for any other freeway (for which definitons vary between states
>IIRC?)

Depends on the design speed. What works for a freeway with a 70mph
design speed would work just as well for an interstate with the same
design criteria.

trekk...@mailcity.com

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Nov 4, 1999, 3:00:00 AM11/4/99
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In article <2xMgON8VLc=JRuR4TPs...@4ax.com>,
John Lansford <jo...@vnet.net> wrote:

> Personally, someone else can seal any project of mine where I am told
> to design the road for traffic use of the shoulder. I refuse to allow
> such a practice to be put into operation on one of my projects.


Thank goodness! No shoulders ,or people routinely violating
use of the shoulders, on the interstate is a dangerous
situation.


Sent via Deja.com http://www.deja.com/
Before you buy.

Michael Torla

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Nov 4, 1999, 3:00:00 AM11/4/99
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John Lansford wrote:

> nwp...@student.berklee.edu (Nathan Perry) wrote:
>
> >Also: an interstate must have shoulders, but must they be used exclusively
> >for non-driving activities? The right shoulder of some parts of I-95 are
> >used as lanes during rush hour, except by exiting traffic which uses the
> >far rightmost of the regular lane. (Horrors!)
>
> FHWA and AASHTO strongly discourage this kind of official sanction to
> use the paved shoulder as a lane. If it is done by drivers without any
> kind of approval by the DOT, there's little that can be done about it.

IIRC, and if things haven't changed since I last drove there, MassHighway had
posted that the shoulders on the 6-lane portions of what was/is MA-128 (also
cosigned I-95/I-93) were travel lanes during "rush hours." In particular, the
entire section of what was MA-128 now signed I-93 was so signed. Rush hours
were 4 hours long both morning and afternoon.

OTOH, 8 lane segments of MA-128 are explicitly posted that the shoulder is
never a travel lane.

One interesting note about these freeways: all the "excepted" interstates in
MA were originally not to be part of I-93. Recall that I-93 was to end at the
Mystic River (now Tobin Bridge) interchange, and north of that point, I
believe I-93 complies with FHWA and AASHTO guidelines. The "central artery",
which was built prior to the IHS, and was originally included as I-95, has a
design speed of 35, no shoulders, minimal medians (with barriers), etc. South
of the Mass Ave exit, the "Southeast Expressway" was built to be a state
freeway, and given I-93 only when they finally gave up building I-95 as
intended inside MA-128. I've driven MA-3/I-93 recently, and I don't recall
it's current setup. When I lived in Braintree in the late 80's, it was
similar to the 6-lane segments of MA-128 in that the shoulder became a travel
lane during rush hour. It's been somewhat rebuilt since.

All of MA-128 (and what was MA-128) was built by the Commonwealth, and was
redesignated (co-designated) I-93 or I-95 at the aforementioned time of
admission.

mt

John Lansford

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Nov 4, 1999, 3:00:00 AM11/4/99
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trekk...@mailcity.com wrote:

>In article <2xMgON8VLc=JRuR4TPs...@4ax.com>,
> John Lansford <jo...@vnet.net> wrote:
>
>> Personally, someone else can seal any project of mine where I am told
>> to design the road for traffic use of the shoulder. I refuse to allow
>> such a practice to be put into operation on one of my projects.
>
>
>Thank goodness! No shoulders ,or people routinely violating
> use of the shoulders, on the interstate is a dangerous
> situation.

Exactly. I can understand the hesitation of politicians and
bureaucrats to fund expensive widening projects, and using the paved
shoulders appears to be an easy and quick way to increase capacity
without much expense, but all that does is encourage that kind of
behavior at other times and on other roads, not to mention making safe
roads dangerous for everyone.

Nathan Perry

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Nov 4, 1999, 3:00:00 AM11/4/99
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In article <fCkiOFt5Wy4yLq...@4ax.com>, John Lansford
<jo...@vnet.net> wrote:

> trekk...@mailcity.com wrote:
>
> >In article <2xMgON8VLc=JRuR4TPs...@4ax.com>,
> > John Lansford <jo...@vnet.net> wrote:
> >
> >> Personally, someone else can seal any project of mine where I am told
> >> to design the road for traffic use of the shoulder. I refuse to allow
> >> such a practice to be put into operation on one of my projects.
> >
> >
> >Thank goodness! No shoulders ,or people routinely violating
> > use of the shoulders, on the interstate is a dangerous
> > situation.
>
> Exactly. I can understand the hesitation of politicians and
> bureaucrats to fund expensive widening projects, and using the paved
> shoulders appears to be an easy and quick way to increase capacity
> without much expense, but all that does is encourage that kind of
> behavior at other times and on other roads, not to mention making safe
> roads dangerous for everyone.

It's also complicated by the fact that only a certain percentage of
drivers remembers to use the shoulders this way. So we have one group of
cars following two different lane configurations on the same piece of
road.

(Worse is that the persons using the shoulder tend to be thru traffic and
those not using the shoulders tend to be exiting/entering. You can imagine
the conflict.)

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