Mapping Urban bridges

[andypat]

On behalf of the Organising team for the Erskine Urban event on 2 April (Entriesd go live on 1 Feb ), does anyone have a workable solution to the following Urban mapping conundrum? Sorry I dont know how to put a pic on here, but the link to routegadget should help

http://www.clyde.routegadget.co.uk/clyde/reitti.cgi?act=map&id=3&kieli=

Basically - if you look at the pedestrian bridge at the N end of the map (there are several others too), its about how to make it clear to runners that you can run under it (despite the thick black lines down each side).

We've tried the underpass symbol, but the span that you can get under is almost the entire length -about 100m(in fact its off the map at the top!), which makes the underpass symbol look like a single row of dots. Worse, the bridge is too narrow and its only actually one dot that shows up in the middle of the bridge (or two half dots joined to either edge).

I dont like the idea of using the canopy symbol as this doesnt really describe somthing you should be able to run over, only under.

We thought maybe to artifically widen the bridge on the map to get some more dots in, but this then starts to overwrite some of the trees next to the other bridges.

Do we simply leave it and make it clear in the final details (Erskine Urban race 2 April 2011!)? Do we use some sort of overprint (like the "low headroom" one from St Andrews to say "route possible under bridge"?

What do potential competitors think is clearest?
PS It didnt matter for the WOC sprint event last year as none of the courses offered route choices that went under the bridges, but it will this time!

[King Penguin]

Sitting at a desk, the intent seems clear from the context, but I accept it may well not do so on the run.
The problem seems to arise where the "under" is wide and the "over2 is narrow - the other way round the underpass dots work fine.
Maybe what is needed is a special non-standard colour meanung "can pass over and under" ?

[smf]

Basically - if you look at the pedestrian bridge at the N end of the map (there are several others too), its about how to make it clear to runners that you can run under it (despite the thick black lines down each side).

For the British Sprint Champs in 2007 EBOR used the following two versions of the Scarborough map.

http://www.ebor.routegadget.co.uk/cgi-bin/reitti.cgi?act=map&id=5&kieli=
http://www.ebor.routegadget.co.uk/cgi-bin/reitti.cgi?act=map&id=4&kieli=

There is a high level footbridge at the south end of the qualification race map which shows the supports of the bridge over a road. This was changed in the final race map to show the high level bridge.

Both maps also show the bridge supports to the high level main road bridge.

[distracted]

You sometimes have to forego absolute accuracy to portray what you need to. In this case, it seems that the important message is that both over and under are valid routes, so as long as the map shows this to be the case then you should be fine.

I'd probably try and widen the bridges so that the tunnel symbol can be used, with an 'artifical' tunnel boundary at the major road edge. But only if it's also possible to move the adjacent trees outward slightly - so long as everything is mapped correctly in relative terms then you should be OK.

Additionally, the sprint map spec states:

"If underpasses or tunnels etc. are to be used in a competition, they shall be empha-
sized with symbol crossing point (708) or crossing section (708.1)."

so maybe just overprint in this case will do the job? It would certainly emphasise the validity of the 'under' route which appears to be the key thing you want to do.

[EddieH]

If this is the area of the map, clearly the canopy symbol is fine as no-one would be running over the bridge.

If however the map is extending northwards so that the bridge is used both under and over that won't do. I think the crossing point symbol, or maybe a row of them would be clearest. Under no circumstances does text and an arrow work.

At this year's World Masters final they had exactly this situation and they mapped the bridge with crossable wall symbols, not a great solution as I along with many expected to turn right only to find the passage way over my head.

[Spookster]

I think the Erskine map as currently drawn is about as clear as it could be. You could add the underpass dot or dots at the point where the overpass becomes passable underneath, but I don't think that would help much.

Looking at other maps where there are narrow overpasses, the London City map just uses the underpass dots, while the Carlisle map used a purple overprint crossing point marking to emphasise the passability underneath.

I don't think a canopy symbol would be appropriate, and certainly not for the bridges you want people to be able to go over.

[andypat]

Thanks guys
Thats interesting about Scarborough. I guess for us in future it might be worth planning courses so that going under bridges isnt an option!
I'm sure the mapper will be reading this too.....

[mappingmum]

What you've got there seems fine to me. The specification makes it clear to me that you can run under.

[EddieH]

Not true Mippingmum. As it stands it is FORBIDDEN to go underneath. The purple overprint crossing point will I think be the best option.

[Roger]

The 2007 ISSOM gives the following widths for various black lines in urban areas:
0.07 mm -- edge of paved area, canopy outline
0.14 mm -- building outline
0.21 mm -- passable fence
0.25 mm -- bridge (i.e. the parapet)
0.40 mm (or more) -- impassable fence, wall, etc
The differences may seem to be small but, provided that the lines don't have a vanishingly small length, most people seem to be able distinguish the 0.21 mm fences from the 0.40 mm ones without much trouble. The given thicknesses suggest that if the map follows the spec then it's more likely that competitors will mistake the bridge for a crossable boundary than an uncrossable one.

(That's certainly what happened to me on my first visit to Stockport: I decided that taking my planned 'crossable' short-cut off the high-level road bridge onto the street below would lengthen rather than shorten my time to finish the course. I can't see any ruling that disallows crossing a bridge parapet, BTW -- can anyone else?)

On the Erskine map, the bridges seem pretty obviously to be bridges, especially once you've been alerted that they're present. Displaying some annotated maps in the start area or start lanes would probably address the issue sufficiently.

It's also worth reading the text in ISSOM about using the 'crossing point' and 'crossing section' symbols.

[pete.owens]

In addition to the bridge parapet symbol having a width of 0.25 mm (rather than 0.4) it also has tags at either end which should also help resolve any ambiguity.

However, it is the main main running level that should be represented on the map. So those bridges that simply lead off the map would be better indicated by the canopy symbol, since the competitor has no interest in what is on top of the bridge.

[seabird]

http://www.maprunner.co.uk/simon/sprintmapsymbols.jpg displays how to handle the problem.

[mharky]

Any reason you've used the high wall symbol instead of the bridge symbol?

[andypat]

Er - I'd have to ask the mapper

[Safety]

Maybe what is needed is a special non-standard colour meanung "can pass over and under" ?

I am a big fan of ideas like this. Lets face it, Urban maps in general don't have "undergrowth" over prints, so why can we not use multiple colours for situations like this. In the forest you map what is overhead/body height and what is underfoot. I would not have any problem if things like this were introduced to the standards for urban maps. It would allow areas with more navigational challenge to be mapped. An issue did arise at the Sheffield event 2 years ago, where two underpasses crossed each other at different heights and caused problems, for some. The mappper did a good job with the symbols available, but a simple symbol for a canopy that you can run on top of (maybe equal stripes of grey and the top surface (be it paved, grass or plants) would have allowed the situation to be clarified.

What people say about the canopy for this northern bridge is true, but I see at least 2 instances where over and under are both valid routes. In the past I have seen the 'cave' symbols (like so >||<) be used to indicate a route underneath. I think this is none standard, but again it does the trick.