Cambridge/University of Cambridge

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Cambridge University has carried out a feasibility study into using OpenStreetMap as the basis for its university maps both on paper and on http://map.cam.ac.uk. Known as 'Project Drake', it was completed in June 2012 after which data is being updated as it changes, and the map is being brought into prioduction. For more information about the project, please contact David Earl

The University commissioned detailed property surveys and has contributed the data back to OSM. However there is additional non-geographical information which it is not appropriate to store in OSM yet which needs connecting to the OSM data. Additionally in order to provide a good service, there needs to be consistency in the OSM data.

This page summarises how the University is being mapped. On the whole, this follows common conventions in OSM, but introduces a few new tags (occupier with respect to buildings, for example) and uses others in novel contexts (ref on buildings and building entrances, for example).

If you make a change affecting University or College property, it would be much appreciated if you would follow these conventions.

Satellite imagery

Note that the survey is being carried out on the ground using distance measuring equipment. While much more accurate than GPS and satellite imagery in principle, accumulated errors, and fitting to existing data, mean that in the end it has unit metre accuracies of the same order achievable with GPS in ideal conditions. However, conditions especially in the dense central properties are far from ideal. In many locations small courts surrounded by high buildings mean that there is no practical GPS signal at all.

Satellite imagery might seem ideal - Bing coverage is excellent. However, it is often not clear from the air where something is a roof at a different level or a ground feature (for example, previously the University Library had a large chunk removed erroneously from its west wall because of satellite misinterpretation). More importantly, many of the satellite images for the city are oblique (the sides of tall buildings are visible) and tiles are misaligned. GPS reveals other unexpected displacements. The result is that satellite imagery, while very useful, cannot be trusted to any greater extent than other sources.

Therefore, please do not be tempted to realign buildings with their aerial imagery. The relationships and distances between buildings has been carefully worked out on the ground.

That is not to say satellite imagery isn't useful. Some parts of buildings are not accessible on the ground. Other times subtle non-orthogonality of buildings and angles between buildings are hard to measure on the ground.

University sites

The University of Cambridge is not a campus university. Its properties are spread across and beyond the city. It has both deep and tenuous links with institutions which are not actually part of the University (Addenbrooke's Hospital, for example, whose buildings share a common biomedical campus with many institutions which are part of the University). For various purposes, including navigation, some properties are grouped by the University into 'sites' which have distinct boundaries. Academic departments and other institutions of the University are often housed in multiple buildings across multiple sites.

Furthermore, the University is famously also comprised of 31 administratively and financially independent colleges. Geographically, the colleges can be considered similarly to sites: they comprise groups of buildings enclosed by a well-defined boundary. However, colleges also have 'outliers': additional properties separate from the main college site (especially residences and sports facilities, but also some academic). Typically these are 'sites' of their own (for example Trinity College's Burrell's Field or 'Clare Colony').

Boundaries can almost always be determined from a combination of bounding streets and boundary walls, satellite observation and information provided by permission of the University.

Site and college boundaries should be closed ways (occasionally multi-polygons) and should be tagged:

 operator=University of Cambridge
 name=Whichever Site (University of Cambridge)

or

 operator=Whichever College (University of Cambridge)
 name=Whichever College  (University of Cambridge)

as appropriate, and

 amenity=university


The site would also have a reference letter, for example:

 ref=M

(which is the New Museums Site). Colleges are identified with their subdomain [or id - TBD] in upper case, e.g.

 ref=DOW

for Downing College. Secondary college sites have an slash-separated suffix, hence

 ref=TRIN/BURR

for Trinity’s Burrell’s Fields site.

Where there is a boundary wall, this should be represented as a separate co-incident way marked

 barrier=wall

(The unlisted tag barrier=railing is also used when appropriate, as is barrier=hedge).

Entrances into the site or college are usually gates in the boundary, hence a node

 barrier=gate
 barrier=lift_gate

or where there is no physical barrier, then

 barrier=entrance


These will also be assigned references (related to the site).

 ref=E-A

and a type

 entrance=main_entrance|secondary_entrance|goods|parking|private


Additionally, specify

 access=private


Site/college entrances specified with barrier are assumed accessible to vehicles, on foot or by bicycle unless explicitly stated otherwise with

 vehicle=no
 bicycle=no
 foot=no

Buildings

Take care with orthogonality: renderings may be made at a much larger scale (zoom level) than is typical on the OSM site.

In addition to

 building=yes

and

 amenity=university (or occasionally, e.g. amenity=library)

University buildings should be tagged

 operator=University of Cambridge

or

 operator=Whichever College (University of Cambridge)


Name should be the name of the building not the department(s) or institution(s) occupying it. Hence

 name=Veterinary Anatomy Building

(not name=Department of Physiology, Development & Neuroscience) except where the building is anonymous, identified only by its occupier.

The occupier should be given using the novel tag 'occupier', hence

 occupier=Department of Physiology, Development & Neuroscience

(where there is more than one separate with semicolons; more than 256 characters TBA). Where occupier is the same as name, it should be duplicated. name will also often be duplicated into addr:housename.

Note in particular that Porters' Lodges and site security huts and offices should be tagged

 occupier=porters
 occupier=security

respectively (n.b. lower case). This will allow these to be marked distinctively on maps. Note: where this is part of a larger building, mark the entrance to the porters' lodge etc instead (see below)

ref is used to identify the building by its internal University designation. These are of the form 'Snnn' where S is the site code (e.g. 'M' for New Museums Site) and nnn is a three digit number, and it is these references which link the map data to the University internal database. For example,

 ref=M031


References are sometimes displayed on plans at the site entrance. However, at one time these were references such as M10A, M10B etc and these have since been renumbered. Plans may also omit leading zeros, but these should be included in the ref tag. Hence for example, ref=M031 Where renumbering has occurred, the superseded reference may be given as

 alt_ref=M10A

Sometimes, the same University reference is applied to several buildings, usually joined in some way (e.g. a terrace or linked by a bridge) because they function as a whole. However for geographical and labelling purposes it can be useful for these to be made distinct. This is done by appending a period and number to the main reference, allocated by the University Computing Service, e.g.

 ref=M031.1

(Consider, for example, the 'Inglis' and 'Inglis A' buildings in the Department of Engineering, separately named and very distinct structures, but referenced the same in the main referencing scheme).

Conversely the same physical building may be split with separate references, but that's fine.

Colleges are not included in any existing central system, but are having building references assigned for this project: the college subdomain (or ID - TBD) (upper case, as above) followed by three digits, e.g.

 ref=DOW010


It may be appropriate to include addr:... tags, but don't assume the street name is the nearest street! Postcodes and streets are usually available in internal University documentation. Also note that the postal address for an institution is not necessarily the same as the building it occupies.

Where institutions occupy some or all of terraces of buildings, it may not be clear where the divisions are. In this case, the whole terrace could be shown as a university building and then nodes used for entrances and the building itself within the terrace outline. This will allow a sensible spot on the map to be marked while not being overly prescriptive about the inaccessible arrangement of internal walls.

Building entrances

It is an important feature of the University map that building entrances are marked and referenced. The conventional way to do this is to include a node tagged

 entrance=something

where something is a type of entrance:

 entrance=main_entrance|secondary_entrance|staff|goods|fire_exit|private|porters|security

or just 'entrance=yes' for insignificant ones (but these will not appear in the University's index).

Significant entrances are also tagged with a reference, e.g.

 ref=M031-A
 ref=DOW010-A

The reference is generated by the University Computing Service, but is typically related to the building reference (though entrances occasionally more than one building). However, note that college residence staircases (residence doors) follow the convention

 ref=DOW--C

example(college subdomain, dash, dash, staircase identifier - sometimes more than one letter, as in PEM--LL; note separate sites may re-se letters, so CAI--BB and CAI/HARVEY--BB). Where two or more staircases share an entrance, separate the letters with a comma, e.g.

 ref=DOW--U,V

Such entrances would also have names

 name=A
 name=U & V


Many (most, perhaps, and even in some new buildings) entrances have steps leading up to them (see below), so it is important to identify those which are wheelchair accessible (though there is no point designating wheelchair access if there is only a set of stairs inside the building).

 wheelchair=yes


Sometimes entrances served by steps also have adjacent external wheelchair lifts. Mark such with a node tagged

 amenity=wheelchair_lift


Many buildings have external spiral staircases. Somtimes these are just fire escapes, but often they are building accesses too. In the spirit of highway=steps, tag a node as

 highway=spiral_staircase

(Note: previously entrances were indicated using building=entrance, but this has since been deprecated by OSM in favour of just the entrance tag).

Archways and colonnades

It is very common to find doorways (and porters' lodges especially) opening off wide, long, geographically significant archways and gateways, or off colonnades within a building footprint. While an isolated node for the building entrance is possible, it doesn't give us direction or building relationship. Therefore, this particularly common idiom is being represented as

 highway=footway (or service etc)
 area=yes
 tunnel=yes
 layer=-1

Typically there is a massive gate at one end, so there will be a

 barrier=gate

with a reference, an entrance type and maybe a name (as above) at the junction between the area and the path or road leading to the gate. For example, the gate to Clare College (note the main gate, and the porters' lodge and staircase B leading off the tunnel).

Then doors off the tunnel are simply

 building=entrance

with all the ancillary tags as above.

Colonnades are similar: tunnels with a long edge coincident with a building. For example, under the Forbes Mellon library at Clare College's Memorial Court site


Roads and paths

All internal highways are

 access=private


Usually, vehicle accessible roads will be

 highway=service

and rarely have names.

Many sites are hard-surfaced between buildings, and where this is more than just a vehicle corridor, it should be represented as a polygonal area

 highway=service
 area=yes

(see also Parking below)

 highway=footway

or possibly

 highway=pedestrian

and often qualified by

 bicycle=yes

for non motor routes. Generally only use

 highway=cycleway

where a route is specifically marked for cycling (such as the corridor down the western side of the Sidgwick Site for example).

As well as gates marking the entrances to sites, there are often barriers restricting vehicle movements. For example,

 barrier=lift_gate

is well defined already. Use

 barrier=rising_kerb

for barriers which rise out of the ground (e.g. in the Old Addenbrooke’s site).

Numerous locations around the University have raised or sunken piazzas or ornamental facades and porticoes accessible by a wide flight of steps, often on three sides or in a semi circle.

Ordinary steps are

 highway=steps
 step_count=N
 incline=up

(with 'up' in the direction of the way). There isn't a very satisfactory representation for very wide steps. For example, the Sidgwick site has steps surrounding almost the whole central area, the largest of which has only four steps but is about 60m wide. Using a single way as per ordinary steps but with width=M has been suggested, but this is hard to get angled exactly right and, while not advocating tagging for rendering, it looks unsatisfactory on OSM.

Therefore, so far I have used multiple parallel ways each marked as steps. In due course, I am inclined to link these with a relation.

Steps are often accompanied by a wheelchair accessible ramp (sometimes also provided for and used by cyclists). This follows current proposals, namely:

 highway=access_ramp

(Unfortunately this does not render at all on OSM currently, but will do so on University maps.)

Parking

Parking spaces simply "on street" in the general vehicle network are not being marked routinely, except for disabled spaces:

 amenity=parking
 parking=disabled
 capacity:disabled=N


Where a proper car park is marked, use

 highway=service
 service=parking_aisle

for its internal accesses, and always designate

 access=private
 operator=... (as above)


Cycle parking is being collected:

 amenity=bicycle_parking
 bicycle_parking=sheffield|t|v|high_capacity (ie. type of stands)
 capacity=N (number of cycles not number of stands)
 operator=...
 access=private
 covered=yes (if it is)

There are a few motorbike spaces around:

 amenity=parking
 parking=motorcycle
 capacity=N

and other tags as above.

Landuse

Colleges especially are rich in greenery.

Use

 landuse=grass

areas for lawns. Ideally use separate areas for separate lawns rather than a single area with a path running across it, especially where the paths are the typical wide gravel variety: these will be used at much higher scales than the usual OSM website, so while not essential it gives a better pictorial outcome.

Only use

 leisure=garden

where the feature is specifically laid out as a garden. Often such gardens have names (Fellows' Garden for example).

 leisure=garden
 name=Fellow's Garden


College "courts" are often used to subdivide parts of a college. In some cases the court might actually be the name of a building, it is more often applied to the space around which buildings are ranged, possibly with somewhat ill-defined boundaries. The same building may face more than one court. In some cases, all the entrances face into one court so "staircase A" may be said to belong to "West Court". In others the same "staircase" (effectively, block of rooms) may have doors onto multiple courts. The courtyard void may be identified without needing to precisely define its boundaries with a novel value for the landuse tag:

 landuse=college_court
 name=West Court
 operator=...

(it is also fortuitiously helpful that Mapnik renders such names)

Colleges may also have woodland in their grounds (more than just a few trees in a row! - which can be individually shown as

 natural=tree

if you want). Woodland is a closed way tagged

 natural=wood


Follow the OSM model for sports pitches and grounds.