Virginia

[Beltway]

<<< sometimes removing a cloverleaf and pushing traffic through a signal can actually increase the capacity of the roadway network >>>

Sure, check out the I-95 interchanges near Melbourne, Florida, they were built in the 1960s as diamond design, later, development was allowed that prevented their expansion to cloverleaf.

Later improved to having massive long finger ramps 3 to 4 lanes wide especially at the signal.  Plenty of throughput but the signals incur a lot of delay.  These are not optimum designs.

[froggie]

Something not mentioned is that converting from a full cloverleaf to a partial also eliminates the weaving sections between the loop ramps.  That can be a big safety improvement, especially on the freeway mainline.

[Beltway]

Something not mentioned is that converting from a full cloverleaf to a partial also eliminates the weaving sections between the loop ramps.  That can be a big safety improvement, especially on the freeway mainline.

That has been mentioned numerous times in the past.  The problem is that it creates new at-grade intersections which have their own safety problems.

[Alps]

Something not mentioned is that converting from a full cloverleaf to a partial also eliminates the weaving sections between the loop ramps.  That can be a big safety improvement, especially on the freeway mainline.

That has been mentioned numerous times in the past.  The problem is that it creates new at-grade intersections which have their own safety problems.

Depends on the design. If you can do it with left turns from the cross street into the ramps that is, IMO, much safer than left turns coming off the ramps. You only have to look one direction, and even if channelized entries are provided you have left merges.

[Beltway]

The problem is that it creates new at-grade intersections which have their own safety problems.

Depends on the design. If you can do it with left turns from the cross street into the ramps that is, IMO, much safer than left turns coming off the ramps. You only have to look one direction, and even if channelized entries are provided you have left merges.

Not sure what 'left turns coming off the ramps' means.  A properly designed cloverleaf would not have that.  If a local road intersection with the arterial was too close to the interchange then I could see where someone entering the arterial from a loop ramp might have to weave quickly to the left lane so that he can turn left onto the local road.  Is that what was meant?  If so that is a design problem on the arterial.

[Alps]

The problem is that it creates new at-grade intersections which have their own safety problems.

Depends on the design. If you can do it with left turns from the cross street into the ramps that is, IMO, much safer than left turns coming off the ramps. You only have to look one direction, and even if channelized entries are provided you have left merges.

Not sure what 'left turns coming off the ramps' means.  A properly designed cloverleaf would not have that.  If a local road intersection with the arterial was too close to the interchange then I could see where someone entering the arterial from a loop ramp might have to weave quickly to the left lane so that he can turn left onto the local road.  Is that what was meant?  If so that is a design problem on the arterial.

https://www.aaroads.com/forum/index.php?topic=8127.0

My opinion is that a B-4 is safer than an A-4, because you only cross one stream of traffic.

[J N Winkler]

My opinion is that a B-4 is safer than an A-4, because you only cross one stream of traffic.

The tradeoff is that B4 creates a situation on the freeway mainline where a link exit ramp is followed in rapid succession by a loop exit ramp.  This can cause operational difficulties when lane drops are involved or inadequate facilities for speed change are provided.  IIRC, one of the early AASHO design references (Blue Book?) said it was preferable that the design speed of an exit ramp be at least 75% of the design speed of the mainline.  While the safety drawbacks of loop ramps can be mitigated by signing, I am not aware systematic investigations have determined the largest achievable extent of mitigation through this means or the optimum signing strategy for it.  This is an area in which large variations in practice are seen among the states.  The B4 design has the added disadvantage in that advance signing for the easy link ramp can obscure signing for the difficult loop ramp immediately following.

Depending on how traffic is distributed among ramps, it is possible to end up in a situation where A4 offers better safety performance than B4 despite its disadvantages in ramp terminal design.

I am not aware of any freeways with chains of parclo B4 interchanges.  However, there are multiple examples of freeways with chains of parclo A4 interchanges, including SR 99 through Bakersfield, California and the 401 through Greater Toronto.

[Beltway]

Depending on how traffic is distributed among ramps, it is possible to end up in a situation where A4 offers better safety performance than B4 despite its disadvantages in ramp terminal design.

Surely there are a few cases where deconstructing a cloverleaf would be an improvement.  Just that it would be rare and I don't know of any such personally.

The I-64/VA-156 project that started this discussion would be the latter.  I attended the Design Public Hearing a couple years ago and made my opinions known to the project engineers and by a written public comment.  There is ample room within the finger ramps to build larger loops with longer weaving lanes, and there is ample room to install C-D roadways to intercept the mainline ramp terminal movements.  The design would also need to accommodate the planned future 6-lane widening of I-64 between VA-156 and I-295, and given the large size of that project maybe that would be the best time to perform the upgrade to the interchange. 

The I-64 bridges over VA-156 do need to be replaced soon, but they could be built to whatever future width is needed just like the nearby recently replaced Nine Mile Road bridges over I-64 (3 lanes and two 12-foot shoulders each way).

[Jmiles32]

Surely there are a few cases where deconstructing a cloverleaf would be an improvement.  Just that it would be rare and I don't know of any such personally.

One particular Richmond area cloverleaf that comes to my mind as being hazardous is the I-95@VA-73(Parham Road) interchange. The loops from Westbound VA-73 to Southbound I-95 and from I-95 Southbound to Eastbound VA-73 are way too tight(15 and 20mph) with minimal weave space in between. IMO a DDI would work better here.
https://www.google.com/maps/@37.6363456,-77.4517262,471m/data=!3m1!1e3?hl=en&authuser=0

[Beltway]

One particular Richmond area cloverleaf that comes to my mind as being hazardous is the I-95@VA-73(Parham Road) interchange. The loops from Westbound VA-73 to Southbound I-95 and from I-95 Southbound to Eastbound VA-73 are way too tight(15 and 20mph) with minimal weave space in between. IMO a DDI would work better here.
https://www.google.com/maps/@37.6363456,-77.4517262,471m/data=!3m1!1e3?hl=en&authuser=0

Agreed.  There is plenty of open land that could be acquired to expand those two loops to near what is on the northbound side, without a DDI.

[jakeroot]

I've been visiting my mother in DC for the last week. She lives in Arlington, and I've spent a fair bit of time driving around Arlington and Alexandria (as well as inside the district). A few observations:

- Bizarre gap in driver speeds on non-Interstates. Some are very quick, yet some are very slow, and don't keep up with traffic. In Seattle, it's very unusual to see cars go below the limit; not here
- Interstate limits don't seem to match driver speeds (55 on I-66, but most cars were going 70+)
- Road quality is pretty good, though some of the roads around Arlington Cemetery aren't that great
- Lots of Clearview, many in negative contrast situations. Some of the brown NPS signage has a lot of Clearview, too (including shields)
- Remarkable amount of "YIELD - NO MERGE AREA" situations (old roads being chief contributor to that, I suppose). Very few of these in Seattle
- Taxi's are the slowest drivers by a mile
- Court House and Rosslyn are extremely walkable (probably like other areas around DC)
- Drivers seem to dive into the non-merge lane pretty quick (though not always). In Seattle, you use the merge lane until it ends

On my drive down to Charlottesville...

- Really awesome speed limits on secondary (two lane) routes. Most felt sufficient. Delaware and Maryland also seem to have good two-lane limits.
- Rural freeway limits felt low, but weren't unreasonable. No one going 80, for reasons I've been previously made aware...
- Awesome farm scenery
- Freeway signage: love the round corners (I hope these aren't being discontinued)
- Related to a note above, drivers seem to merge way before the lane ends. In one situation, drivers merged left about two miles before a crash on I-64, despite no signs indicating any closed lanes. I stayed in the "closed" lane, but when I arrived at the crash area, the lane was open. Bit of a lemming situation that would be rectified by drivers using all available lanes until merging becomes physically necessary

[Beltway]

- Court House and Rosslyn are extremely walkable (probably like other areas around DC)

Metrorail Vienna Route passes under that area, completed out to Vienna since 1986.  Lots of high density development enabled in that whole corridor from Rosslyn to Ballston.  Court House and Rosslyn are now part of the urban core of the D.C. area.

[1995hoo]

Many people in Virginia are determined to get over early. During heavy traffic periods it's common to see people stopping at the beginning of the merge lane trying to shove over–but on the other hand, in some locations it's then common to see people in the thru lanes moving right to use the merge lane to pass stopped traffic (very common on I-395, especially near the Pentagon).

[plain]

Yeah traffic in this state has been bad for so long that most Virginians know when and where the backups begin so we maneuver accordingly. This is why it's common to see traffic stacked into particular lane(s) well before the desired exit or split.

[cpzilliacus]

I've been visiting my mother in DC for the last week. She lives in Arlington, and I've spent a fair bit of time driving around Arlington and Alexandria (as well as inside the district). A few observations:

- Bizarre gap in driver speeds on non-Interstates. Some are very quick, yet some are very slow, and don't keep up with traffic. In Seattle, it's very unusual to see cars go below the limit; not here

I think it  depends on where you are.  Municipalities with  notoriously strict speed limit enforcement, especially in Virginia (City of Falls Church and Towns of Leesburg, Vienna and Haymarket) experience that.  There are plenty of speed cameras in D.C. too.

- Interstate limits don't seem to match driver speeds (55 on I-66, but most cars were going 70+)

A bigger problem on the Capital Beltway, especially Prince George's County, Maryland where the design speed was 70 MPH (and most of it posted 70 prior to 1973), yet the 55 remains from the days of NMSL.

- Road quality is pretty good, though some of the roads around Arlington Cemetery aren't that great

In the cemetery, the maintenance is by the federal government, as are some roads leading up to it.

- Lots of Clearview, many in negative contrast situations. Some of the brown NPS signage has a lot of Clearview, too (including shields)

I am not aware of any of the NPS parkways having brown signs with Clearview or FHWA, except for a few panels approaching MD-32 in Anne Arundel County.

There are green signs with FHWA at places where there are interchanges between the parkways and Interstate highways. 

What you  might have seen on the parkways that looks a little like Clearview is the NPS standard sign font, NPS Rawlinson - or its predecessor Clarendon.

- Remarkable amount of "YIELD - NO MERGE AREA" situations (old roads being chief contributor to that, I suppose). Very few of these in Seattle

Less than there used to be, fortunately.

- Taxi's are the slowest drivers by a mile

Not always. Some cab drivers have lead feet.

- Court House and Rosslyn are extremely walkable (probably like other areas around DC)

Arlington is arguably the most walkable place in metropolitan Washington.

- Drivers seem to dive into the non-merge lane pretty quick (though not always). In Seattle, you use the merge lane until it ends

Many D.C. drivers speed-up to prevent merging drivers from getting in front of them.

On my drive down to Charlottesville...

South of Culpeper, the Greene County, Virginia Sheriff's Office used to run a fair amount of predatory speed limit  enforcement on U.S. 29.  Maybe less these days.

- Really awesome speed limits on secondary (two lane) routes. Most felt sufficient. Delaware and Maryland also seem to have good two-lane limits.

Often 50 MPH or 55 MPH.

- Rural freeway limits felt low, but weren't unreasonable. No one going 80, for reasons I've been previously made aware...

80 MPH or higher is a very bad idea in Virginia.

- Awesome farm scenery

Close to D.C., those are probably mostly hobby farms owned by  wealthy lobbyists, lawyers and physicians.

- Freeway signage: love the round corners (I hope these aren't being discontinued)

In Virginia, but  installs in past 10 years not so much.

- Related to a note above, drivers seem to merge way before the lane ends. In one situation, drivers merged left about two miles before a crash on I-64, despite no signs indicating any closed lanes. I stayed in the "closed" lane, but when I arrived at the crash area, the lane was open. Bit of a lemming situation that would be rectified by drivers using all available lanes until merging becomes physically necessary

See above - some drivers speed-up to deter a lane change in front of them.

[1995hoo]

Some of the all-caps text on the bottom lines of the brown signs in the GW Parkway certainly looks like Clearview.

[jakeroot]

- Court House and Rosslyn are extremely walkable (probably like other areas around DC)

Metrorail Vienna Route passes under that area, completed out to Vienna since 1986.  Lots of high density development enabled in that whole corridor from Rosslyn to Ballston.  Court House and Rosslyn are now part of the urban core of the D.C. area.

They've done a very good job with that metro, minus construction and maintenance delays. The past week, I've been kept waiting quite a bit due to 20 minute trains. Faster to walk from Court House to Rosslyn (until today).

Many people in Virginia are determined to get over early. During heavy traffic periods it's common to see people stopping at the beginning of the merge lane trying to shove over–but on the other hand, in some locations it's then common to see people in the thru lanes moving right to use the merge lane to pass stopped traffic (very common on I-395, especially near the Pentagon).

In my I-64 situation, that's what I started seeing once I went past in the "merge lane". I think people we're so focused on merging, they didn't bother to notice the total lack of signage indicating any lane closures.

Some of the all-caps text on the bottom lines of the brown signs in the GW Parkway certainly looks like Clearview.

That's where I've been seeing it, as that's where I've been doing 90% of my driving. I'll try to find a a way over there on foot, as I think the blue metro line train is out.

cpzilliacus, if I could more easily quote your post on mobile, I would address you directly. Please see my above response to 1995hoo.

[1995hoo]

The Blue Line is back in service along its full route as of today.

[jakeroot]

The Blue Line is back in service along its full route as of today.

Just managed to catch one.

Here's some of the signage I was talking about. Only what I could reach on foot:

[Takumi]

Petersburg has replaced most of its VA 36 shields with US shields in recent months. Some are two-digit shields and some are three-digit shields, so I have to imagine there's some sort of cost-cutting factor going into this.

[WillWeaverRVA]

Petersburg has replaced most of its VA 36 shields with US shields in recent months. Some are two-digit shields and some are three-digit shields, so I have to imagine there's some sort of cost-cutting factor going into this.

It's Petersburg, so that's hardly a surprise. I might have to go get some pictures.

[NJRoadfan]

Surely there are a few cases where deconstructing a cloverleaf would be an improvement.  Just that it would be rare and I don't know of any such personally.

The world's first cloverleaf at US-1&9/NJ-35 was deconstructed due to tight ramps. Other examples tended to be between high speed roadways where loop ramps were replaced with flyovers to fix weaving problems.

[Beltway]

The world's first cloverleaf at US-1&9/NJ-35 was deconstructed due to tight ramps. Other examples tended to be between high speed roadways where loop ramps were replaced with flyovers to fix weaving problems.

Replacing a loop ramp with a semi-directional ramp is an upgrade, no deconstruction there.

[1995hoo]

....

On my drive down to Charlottesville...

South of Culpeper, the Greene County, Virginia Sheriff's Office used to run a fair amount of predatory speed limit  enforcement on U.S. 29.  Maybe less these days.

....

The worst place used to be Madison County on the southbound straightaway just north of the Bavarian Chef: https://goo.gl/maps/dwNu9sTADsH2  I don't know whether it's better now because I don't usually take Route 29 to Charlottesville (it's out of the way), but when I was in school there, everybody knew about the speedtrap there, yet everyone (myself not included) kept getting pulled over anyway, which never made any sense to me. I know that flat straightaway makes it easy to want to go 70+ mph, but when you know the area is a speedtrap, why would you do that?!!! Good spot to set the cruise control a tick above the speed limit, which I believe is now 60 mph (it was 55 during my college days), and let someone else show off how fast he thinks his car is.

[cpzilliacus]

The Blue Line is back in service along its full route as of today.

Just managed to catch one.

Here's some of the signage I was talking about. Only what I could reach on foot:

The top line (including the numerics) look like Frutiger, which resembles in some ways Clearview.

The middle and bottom lines appear to be NPS Rawlinson.