Re: Speed limiters

On 7/7/2024 12:09 PM, Martin Brown wrote:

On 07/07/2024 18:51, Don Y wrote:

On 7/7/2024 2:56 AM, Martin Brown wrote:

Investment in "smart motorways" which allows them to use all 4 lanes as live running lanes (3 properly designed to be running lanes and one hard shoulder intended as a refuge for broken down vehicles).

>
How does "smart" make that possible but "not-smart" doesn't?
Do your roadways "change directions" based on time of day?
(we have center lanes that do so to expedite traffic into
or out of busy areas based on traffic patterns -- but, they
are time driven)

 In theory the smart motorways are monitored along their length by cameras and control rooms. Each lane has a tick or a red cross above it to indicate if it is in use or not available. At peak times all lanes are run live which leaves no room for error whatsoever.

I don't understand -- they are taking capacity OUT of service?

Emergency vehicles have to fight their way through traffic if something happens (as opposed to going down the non-running lane hard shoulder).

That seems to be a bigger problem "in town", here.  Largely because
traffic is naturally stopped at frequent intervals along any travel
route.  Convincing three lanes of "parked" (at traffic signal)
traffic to get the hell out of the way for an emergency vehicle
approaching from behind is a bit of a chore.
Such vehicles are equipped with a strobe light that visually signals
a sensor mounted high in the intersection.  It ties in to the local
signal controls and overrides the timing to allow traffic along
the "approach axis" to move, even if it would normally be halted.
In theory, that traffic starts moving (making the blockage more
fluid) and they can then get out of the way of the approaching (from
front or rear) emergency vehicle.
Too often, drivers "freeze" thinking that the emergency vehicle can
sort out its dilemma.  For undivided roadways, the emergency vehicle
will often cross the centerline to use the lanes in the opposite
direction to get around idiot drivers "ahead" of it.

[IIRC, DC? had similar roads that would change direction
based on time of day]

 There were a few of those in the UK. One in Manchester London Road 4 lanes under flow control depending on the time of day. 3 in for morning rush hour and 3 out in the evening they were notorious for head on crashes. Picture from the late 1970's:
 https://www.flickr.com/photos/gmts/33623521145
 An even worse configuration in the 1970's was the three lane trunk road with the centre lane for "overtaking only". They resulted in the most spectacular head on crashes (think 150+mph closing speeds) and caused collateral damage in the adjacent lanes. Not survivable.

The center "suicide" lane in most roads, here, is for taking left turns
across traffic (remember, we drive on the right).  It also finds use for
traffic trying to enter the roadway via a left turn; they can pull into
the middle lane and essentially *sit* there until it is clear to pull
further to the right in the right lanes.

Most roads have predefined lanes in each direction.  Some roadways
are further (physically) "divided" to isolate traffic from each
direction.

 UK motorways have strict central reservation barriers which are being reinforced to heavy weight solid cast concrete with tensile steel inside to stop the larger HGVs going straight through them.

Our "interstate" highways tend to have a large median between divided
lanes.  So, crossing over the "center line" ends up with a vehicle
in grass/ditch.
Of course, this is only possible in places with ample real estate.
Such roads traveling through metropolitan areas can be hazardous as
the concrete "prisms" placed end to end are really only massive enough
to *deflect* traffic, not *stop* it.  This is particularly true of East
Coast cities where "walking trails" became early roadways...
<https://en.wikipedia.org/wiki/Cross_Bronx_Expressway>
<https://en.wikipedia.org/wiki/Interstate_495_(New_York)>
<https://c8.alamy.com/comp/BR80PR/traffic-on-storrow-drive-in-boston-massachusetts-BR80PR.jpg>
Though there were roadways in Chicago that were similarly harrowing:
<https://upload.wikimedia.org/wikipedia/commons/b/b5/The_Loop%2C_Chicago%2C_Illinois%2C_Estados_Unidos%2C_2012-10-20%2C_DD_03.jpg>
Your car seems DRAWN to those metal uprights IN the roadway!  (I have
no idea how they managed to film The Blues Brothers car chase -- and
subsequent police car pileup -- there!)  Likewise for Lower Wacker:
<https://i.pinimg.com/originals/d1/dc/44/d1dc443826f2c9fde43456351a4c7f8d.jpg>
<https://c8.alamy.com/comp/WDK97R/intersection-on-lower-wacker-in-downtown-chicago-WDK97R.jpg>

It didn't take account of dumb drivers or of the need to properly maintain the camera systems used to monitor the road situation. As a result they are having to add a lot of extra refuges to the "smart" motorways to make them safer after several very high profile nasty high speed collisions between motorway traffic and broken down vehicles.

>
Stopping *on* the roadway is often forbidden.  Your vehicle must be
pulled off, onto a shoulder (outside the outside lane -- far right in
our case).

 That is the point of "smart" motorways. There is no hard shoulder to pull off onto - it is a live lane just like all the others. You can't always control where you breakdown either. There are refuges from time to time but far too far apart to be any use.

Ah.  Most roads, here, have a shoulder -- though sometimes "soft".
It is not uncommon to see someone trying to change a flat tire on the
driver's side ("in-side" of the roadway) of their vehicle.  A patrolman
will "run interference" for you *if* he comes upon you.  Otherwise,
you work with one eye always watching oncoming traffic.
Police officers are often at risk in roadside stops as the *vehicle*
may be on the shoulder but the officer standing beside the driver's
door/window will have his ass out in traffic.
["distracted drivers" care little about what they may hit!]

In my student days we got stuck immediately behind a vehicle in the outside lane (long before mobile phones). What happened next was very interesting. A pair of heavies saw what had happened from a distance behind us and created a rolling road block. When they had stopped all the traffic we got out and pushed the dead car onto the hard shoulder and then got back in our car and continued our journey. It was touch and go whether someone would pile into us when we had to stop like that.
 

A patrolman encountering such a vehicle will likely park his vehicle
upstream of it to further alert oncoming traffic to the hazard.

 Same in the UK. Highways agency vehicles have damn big flashing please don't hit me signs with an arrow that can be erected behind them.

Police will usually walk back upstream and deploy flares to warn of their
stationary presence, "ahead".

Work on the roadways (overhead signage, pavement, etc.) usually results in
overly long stretches being cordoned off ("dunce cones") to ensure traffic
is clear of the work area BEFORE encountering it.

 There is a lot more of that work at the moment because of the crisis with smart/dumb motorways. They are dumb as hell when the smarts that are supposed to keep them safe are not working!

"Something" is always under construction, here.  You may travel across town
and stumble onto three or four different "projects" if you are unlucky enough.
It isn't practical to try to keep track of all of them (though the news
media cover them nightly along with appraisals of current travel times)
unless your normal travel route has you encountering them.
The standing joke is that they will pave a roadway (we recently were asked
to approve $1B -- 10^9 -- for road repairs "in town") and, as soon as the
asphalt has cooled, they will dig it up to work on the SEWERS below!
(something about left hand not knowing the right hand even EXISTS!)
For a while, firms wanting to install communications infrastructure
were essentially given a free pass to work anywhere they "had to".
And, of course, company A and company B rarely share their plans
with each other...

And, most roadways enter and exit on the outside (right) lane so you
can predict where the "varying" traffic will originate.

 Opposite sense in the UK, but we do have a few free for all junctions on urban motorways where traffic is injected and must leave from the outside (fastest) lane. A recipe for high speed collisions.

"Rotaries", here.  No traffic control signals as they are intended to keep
traffic MOVING.  Not a place for the timid!

The smart motorways I drive regularly I have such totally misleading and misguided signs that I no longer trust them to tell the truth. Worst example I saw was alternate gantries showing 40mph speed limit(as low as it actually goes on a motorway) and 60mph. I think the control room were messing about to see what traffic chaos they could cause.

>
The closest thing to "smart" here is signage that may dynamically
reflect some condition of interest (amber/silver alert, construction
ahead, etc.).  We have some automated technology that warns of haboobs
in areas prone to them as they instantiate in time frames too short to
erect manual signage (radar).  I'd wager there are parts of the midwest
where similar systems warn of tornados.

 They could be a useful if they were properly maintained and drivers understood them. Unfortunately neither condition is met in the UK.

As with much technology, the haboob warning system "has issues".  There are
also broadcast (cell phone) alerts regarding weather, abducted children,
missing grandparents, etc.
But, I suspect much of this does more harm than good as it tends to
overload folks' attention spans.  Am I going to take out my phone to
see what the alert says, while driving?  When the law forbids me from
operating my phone while driving??!

There are also variable speed limit motorways and roads equipped with the latest average speed camera technology. That is also part of smart.

Trying something like that at the federal level would require a
shitload of money due to the amount of asphalt involved.
And, at the state level, any investment would likely exceed their
local funding sources (e.g., that $1B for my *town*!)
So, you encounter a variety of different "solutions" depending on
where you live/drive.
E.g., our traffic signals tend to be different than other places I've
lived (here).
Left turns (usually a special lane) often have a dedicated signal
to expedite their travel ACROSS oncoming traffic.  In most places,
this is LEADING left:  all traffic along your axis is stopped.
The left lane is given permission to go while through traffic
remains stopped.  Then, thru traffic is enabled to proceed while
left turning traffic is halted.
*Sometimes*, left traffic can proceed in the face of oncoming
traffic, /if safe to do so/.  Other times it is prohibited.
Lately, we have a "flashing yellow" left arrow that says,
"go if you can do so safely".  WHEN it appears -- and in
which intersections -- requires a Ouija board to ascertain!
But, *here*, left turns are LAGGING; through traffic proceeds
first.  Then, it is halted and left turn traffic allowed to proceed.
[The caveats above also apply]
Which intersections are LEADING vs. LAGGING is something that
one can't easily predict.
Some turns are expected to be executed "at speed" -- the road
onto which you are turning has set aside a lane just for your
incoming traffic.  Others expect you to merge left into
existing traffic.
Some intersections you travel THROUGH; then make a U-turn
half a block later and come back to the intersection to
turn RIGHT (whereas your original intention was to turn LEFT).
Some intersections are multilevel -- allowing thru traffic
(orthogonal!) to proceed at speed while entering and exiting
traffic has to merge with those.
There's an intersection not far from here where orthogonal traffic
turning left into a roadway has two "protected" (lane divided)
lanes to occupy -- that must then merge RIGHT with the existing traffic.
Usually, the loss of a lane ("lane ends ahead") is a merge left
scenario.  Unless it is a merge RIGHT!  (WTF?)
And, of course, any roadwork throws all of the above up in the air!
There's no real *pattern* to what you can expect to encounter.