[Talk-GB] Fwd: Underground services

Donald Noble drnoble at gmail.com
Tue Jan 20 21:06:11 UTC 2015


Just my 2c on this.

I think that complex micro-mapping of services in towns and cities is a
very difficult problem, and is perhaps only really useful if there is a
good level of accuracy. Cf routing between towns and cities, if I know
there is a road linking London and Edinburgh, i can follow it by car — even
if it is not much more than a straight line. Whereas the position of
underground services in built up areas really needs to be known to within a
metre in x,y&z for any use case I can think of. But that's not the case for
major linking infrastructure. Eg we have many main (and minor) power lines
mapped, plus pipelines for hydropower schemes etc. which are more on a
scale of 10s or 100s of metres.

Many roads appear first in OSM as lines liking two points, which are then
improved over time by many edits. So I don't think the fact that Tim only
has end points is necessarily a reason not to include in OSM (presuming of
course that the data are usable licence wise).

I have often wondered about mapping gas pipelines from the (prominent
orange) marker posts that appear next to the sides of roads. I have mapped
the posts on occasion, but not tried joining them up. I can imagine that
even knowing you are within 100m of a main gas pipeline is useful to take
avoiding measures, or look at a more detailed map.

As for rendering, I think most people would agree this is not something to
be included on the main map tiles, and would probably only redisplayed on
specialist maps (along the lines* of openrailwaymap.org). * no pun intended.

Cheers, Donald



On 20 January 2015 at 14:03, Andy Robinson <ajrlists at gmail.com> wrote:

> There is big money poured into underground utility mapping. The older the
> city the bigger the problem. There are commercial mapping companies who
> specialise in offering a service in this area. Mapping involves many
> different tools and research is currently ongoing between the EU and USA
> and elsewhere to develop multi sensor tools to aid the process. Have a look
> at http://www.mappingtheunderworld.ac.uk/ for example.
>
>
>
> The lines of sewers and some storm drains are often easy to plot because
> they are generally in straight lines between manhole covers (note though
> that the line of the pipe may not be directly below the cover). For nearly
> all other utilities you need other methods. Scars (reinstatements) of the
> highway can identify some utility paths, especially for recent works, but
> you will not necessarily know what the utility is below. Piggybacking off
> others who have spray painted areas to show utility routes might work for
> very local issues but they rarely show the full picture and is just
> provided as a guide to contractors to reduce risk and improve safety when
> excavating. A lot of utilities get damaged when contractors dig up the road
> for other utility repairs or upgrades.
>
>
>
> Traditionally contractors have used a simple tool called a CAT and Genny,
> which is combination of a “Cable Avoidance Tool” and a “Signal Generator”.
> The CAT can detect most but not all electrical cables and other
> conductors.  In Generator mode a separate signal generator is attached to
> part of a pipe or other piece of the utility, like a valve, and the
> detector can then map this signal as it passes through the metal.
>
>
>
> For plastic pipes (HDPE and PVC mostly) there is minimal external means of
> identification other than using Ground Penetrating Radar and even then it
> requires a lot of interpretation, especially when there is a lot of other
> utilities in the vicinity. Mapping below reinforced concrete road slabs is
> very difficult.
>
>
>
> Not all pipes and cables are in use. There is a lot of defunct asset in
> the ground which you often don’t know whether is in use or not until and
> excavation is done and a verification process undertaken.
>
>
>
> There is also the added difficulty that most utilities lie within the
> public highway (Road or pavements) and safe access for mapping normally
> means shutting part of the street down.
>
>
>
> So in summary it’s a complex issue with no easy win. Sewers can reasonably
> be inferred along most streets but there are few options for the amateur
> mapper looking for other utilities in urban environments.
>
>
>
> Cheers
>
> Andy
>
>
>
> *From:* Tim Waters [mailto:chippy2005 at gmail.com]
> *Sent:* 20 January 2015 13:07
> *To:* Pmailkeey .
> *Cc:* talk-gb
> *Subject:* Re: [Talk-GB] Fwd: Underground services
>
>
>
> I'm also interested in underground cables and mapping communications
> routes, in particular the major internet "trunk" cables.
>
>
>
> My question would be, similar to tunnels and other somewhat hidden
> underground features -  how would we represent lengths along the route
> where the positioning is unclear.
>
> Before better sources of positions become available, would straight lines
> in the database from A to B be allowed, or desired?
>
> Shouldn't these unclear, holding lines never be rendered?
>
>
>
> And, more interesting: how can we get better positioning information?
>
> Could the scars along roads be used to help interpolation of positions?
>
> Could we develop hand held instruments to detect various things?
>
> Does dowsing work?
>
> Can we use the markings sprayed on the pavement by utility companies to
> identify what's there?
>
>
>
> Cheers,
>
>
>
> Tim
>
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>
>


-- 
Donald Noble
http://drnoble.co.uk - http://flickr.com/photos/drnoble
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