[Tagging] Sample tagging for highways with no lane markings

Paul Johnson baloo at ursamundi.org
Thu May 24 02:57:26 UTC 2018

On Wed, May 23, 2018 at 10:34 AM, Tod Fitch <tod at fitchdesign.com> wrote:

> On May 22, 2018, at 12:48 PM, Paul Johnson <baloo at ursamundi.org> wrote:
> In the case of your typical bog standard American residential street, I'm
> strongly disinclined to agree that this is a two lane situation.  I'd be
> inclined to mark unpainted lanes in the cases where channelization
> regularly occurs without the pavement markings anyway.  This isn't the case
> on residential streets, as people will tend to drive right up the middle of
> such streets, only movingly right to meet oncoming traffic and maybe when
> approaching a stop sign.
> Hmmm. I guess driving culture may vary from place to place in the US. I
> always keep to the right regardless of the existence of a lane markings. I
> will admit, however, that traffic studies indicate that the average driver
> will be a bit more to the center of the pavement if there are no lane
> markings. Similarly, at least in residential areas, it has been found that
> drivers will generally go slower if there is no center marking. At least
> that is the rational my local government is using to remove the center
> divider marking for traffic calming purposes.

While this may be true, most people will shy towards center (and perhaps
even stay in center) for most of their trip down a standard width street
(which, while typically 40 feet, this is *inclusive* of all features
including sidewalks, making the effective width of the roadway closer to 25
feet, a random pull from Mesa, Arizona's design guide
<http://www.mesaaz.gov/home/showdocument?id=1044> blindly from Google
confirms this, with their design guide being 27 feet across between curbs),
means that two full size pickups can (barely) pass two cars parked on
opposite sides of the street at once.  That's also generously wide compared
to a lot of places, many suburban and small town residential streets I've
encountered are open-edged with parking off the paved area, and the paved
area being maybe 20 feet on a particularly wide street.  New urbanist
street designs are similarly, deliberately, narrow as a traffic calming
measure, as parked vehicles will tend to provide de facto ad hoc chicanes.
As such, if lanes are marked at all, it's usually at the very ends of
blocks only, where parking is prohibited, as a confirmation that the street
is indeed two-way and provide a hint as to the default passing rule.

I know that road design varies over the world and even, to a certain
> extent, within different states in the United States. So this discussion is
> showing different regional points of view. A typical, or to borrow the UK
> slang  “bog standard”, American suburban residential street is wide enough
> for parallel parking on each side and space for trucks/lorries to get past
> one another [1]. Typical parking lanes are about 8 feet (2.4 meters) and a
> typical traffic lane is 12 feet (3.7 meters). So a total pavement width is
> typically around 40 feet (12.2 meters). In some parts of the world, even in
> older crowded US cities, a road of that width might be striped for four
> lanes of traffic. But a typical US residential street has no lane markings.

US tends to favor 9 feet per lane and 6 or 7 foot parking strips for a full
size residential street (and combine with 6 feet being the minimum, 7
becoming common, and even wider in some places for the bike lane, this will
feel quite clausterphobic and many, if not most, drivers who will yield the
entire space to a vehicle passing a parked vehicle first to stay out of the
door zones).  Per federal guidelines, a boulevard would be at least 10,
preferably 11 foot lanes (and this will still feel quite narrow to most
American drivers).

> I can see the logic of only using the lanes tag if there is paint on the
> pavement. But that leads to another issue: It is pretty easy from
> experience to glance at a photo of a road and say it is wide enough for two
> lanes of traffic. But it is much harder for me to determine a width
> accurate to a couple of feet. I don’t see a way to show a measurement error
> estimate [2] and listing something as width=40'0" implies much more
> accuracy than a guess based on a quick visual survey or imagery actually
> provides.

Look for the wear marks, these will be quite prominent in sun-prone areas
and where concrete is used.  Generally speaking if there's defined lanes
that are just worn off, there will be wear marks where passing motorists
have rolled the same spot repeatedly.  This can often be confirmed with
your favorite license-compatible street-level imagery or a survey.  Though
if you're using JOSM and have suitably high resolution aerials available,
you can use JOSM to draw a line perpendicular to the way from curbface to
curbface to find the width.

> I am rambling. To the point, if I were to add my photo [1] to the urban
> highway tagging examples page of the wiki [3] what tags should it have. My
> current guess is:
> highway=residential
> parking:lane:both=parallel
> sidewalk=right
> surface=asphalt
> width=40'

> For the specific example given by the photo, what tags would you suggest.

Probably closer to 34'0" wide (we're still in agreement on customary units
that the inches should be included even when not necessary when tagging?),
since those vehicles are narrower than a full size pickup (typ. 7 feet) and
up against the curb, and so I'm reasonably sure there's not more than 22
feet between them, but more than 18 feet.  I'd still leave off the lanes.
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