Persistence in the Urban Environment : 1

Anyone reading this blog should have realised that I am interested in using maps to understand how the environment we live in has changed over time. I know I share this interest with many other OSMers. There have been many proposals, and discussions about how we might use some of the principles and technologies of OSM to create maps representing an area at some historical time point. I am greatly heartened that a new mailing list (http://lists.openstreetmap.org/listinfo/historic) has appeared for interested parties to share ideas on this subject:

Wollaton Park Estate from the E, (June 1928)

One problem which has exercised my mind, and particularly from my exercise at looking at the OSM edit history of Berlin, was how adding a history (or time) dimension to geographical data might impact on data volume. In thinking about this I have been struck that a very large proportion of the urban environment of cities in Europe and North America is remarkably static. This was brought home by the recent availability of historical aerial photographs of Great Britain (at the Britain from Above website).

Wollaton Park Estate on OSM

The image and OSM map above show the same area, one in 1928, the other as mapped from 2009 onwards. The main estate, Wollaton Park Estate, is in all major features unchanged in the two images. The area in the background, Wollaton Park, itself is also largely unchanged, whereas the area in the foreground has changed at least twice in the intervening period: a large bicycle factory was built over the canal in the 1950s; this in turn was demolished and replaced by a new campus for Nottingham University during the late 1990s. Many other areas of Nottingham show the same pattern of a persistent street layout, often with exactly the same buildings (or at most minor infill, or replacement). Some are shown below:

Lenton Abbey in 1930	Lenton Abbey on OSM
Bulwell Hall in 1930	Bulwell Hall Estate on OSM
Sherwood area in 1930	Sherwood area on OSM

Now all these examples are building developments around Nottingham which were completely new in the 1920s. In fact these are just typical, in that for most urban areas the basic structure of roads and buildings remains after the initial development. Areas which change frequently after the initial change from countryside are quite a bit rarer, and often fall into a number of discrete categories: campus sites (schools, hosptals, universities, etc.), railway land, industrial areas, and 'urban regeneration areas'. Of course the historical core of a town or city reflects a much longer history of change, although even here it is not unusual for much of the skeleton of the environment to remain persistent.

I have tried to categorise areas within the current boundaries of the City of Nottingham according to how many phases of development they have had since about 1850. The categorisation is incomplete as for areas I have not surveyed in detail for OSM a fair amount of desk research is needed. I have used a variety of documentary sources: aerial photos, old maps on the councils GIS site, old maps in my personal collection, local history websites etc. Only when all areas are categorised will it be possible to suggest the overall proportions of the city which for practical purposes of historical mapping have remained invariant. The partial map below suggests it will be quite high.

Areas of Nottingham classified according to degree of change since urbanisation.

 The categories 0-3 are as follows:

• 0 Non built-up areas which have not changed significantly since 1850. This includes: parkland, some allotments (Nottingham has several areas which are over 150 years old), some old cemeteries and any remaining farmland within the city. 
• 1 'Unchanged' areas where the road layout and the majority of buildings are the same as when the area was first built over. These areas date from as early as 1840, with major clusters around the end of the 19th century, between the wars (when the council built about 17000 houses), and the continuous expansion post war. Of course in many of these cases some properties will have had only one occupier for their entire history. 
• 2 Changed areas which have received two distinct phases of urban development, usually with significant changes of street layout and extensive loss of buildings between phases. Two areas of slum re-development are included here - The Meadows and St. Anns - although current plans suggest these will be radically altered in the near future. A surprising number of school sites feature in this category, with several schools built in the 20th century having subsequently been replaced by housing, whereas in others the buildings have been replaced entirely. Hospital and University sites often have seen a continuous re-working of their road networks and buildings. The 20th century colliery sites of Wollaton, Clifton, Broxtowe and Cinderhill are included here (parts of the latter two are Country Parks), as are the Bulwell Stone quarries. 
• 3 Radically changed areas which have received 3 or more phases of re-development. A classic area is the Victoria Shopping Centre: prior to 1900 this contained a workhouse and slum housing, it was then a railway station for around 70 years, and has been a shopping mall for since 1970 or thereabouts. The inner-city area of Radford also features here: much of the area was re-developed during the 1960s and 1970s, but some of the re-development has itself been replaced and their has been extensive modification of the area, in part because it is close to both Universities. Radford always had a mix of housing and industry. Similar areas in the city are the Willoughby Street area of Lenton, and New Basford. Radford is prominent because it is the site of two former major employers in the city: John Player and Raleigh Cycles.

I've had a quick look at a few other areas in other cities to see if the same principles might hold true:

part of Squirrel Hill, Pittsburgh from G.M. Hopkins plat-book (1939)
source: University of Pittsburgh

Squirrel Hill & Oakland in Pittsburgh. Pittsburgh University has an amazing collection of (extremely) detailed maps of land plots dating from 1870 through to about 1940. I've mainly looked at details for the late 1930s for the area of the CMU campus, and streets north of Schenley Park up to Wilkins. As in Nottingham the CMU campus area has seen significant change, as have the Pitt campus area further W (including, of course, the demise of Forbes Field) and the hospital district also in Oakland. The residential area to the east of Beeler Street is largely as it was when laid out in the 1930s. One interesting exception is the residential area west of Beeler Street to Morewood Avenue (a hint of the original layout can be seen on this map of 1915). In the 1930s this area consisted of very large houses on large plots. The owners' names give a very good idea of where the money came from: Heinz, Mellon. Even in the 1960s a lot of these houses were becoming derelict. I don't know what aspect of social change encouraged the rich to move out of the city, but presumably this housing stock was difficult to re-use. Other areas of Pittsburgh have, of course, seen radical change in landuse: particularly former areas of steel production. These latter appear to have mainly been along the banks of the Allegeny and Monongahela rivers. It is interesting that very few of the historical maps here show industrial areas.

Aerial view of Aussersihl, Zürich, 1904. (source Wikimedia Commons)
Guterbahnhof in right foreground,
Kaserne and Zeughaus obvious in middle centre left,
Stauffacherstrasse only partially built-up, Backeranlage appears to be laid out formally.

Aussersihl and;Altstetten in Zurich. SwissTopo has both the Dufour Karte and the Siegfried Karte (c. 1881) online. I also consulted a 1932 Baedeker (I don't have my 1911 one to hand). For Aussersihl the vast bulk of the street network and many buildings are pretty much as they were when built (many around the start of the 20th century) and can be seen in the photo above. Even some of the tram lines had the same numbers and colour codes in 1932 as they do today. The line of Sihlfeldstrasse is visible as a field path on both early maps. Altstetten is rather more complicated. Even in the Siegfried Karte it is a small nucleated village, and not much has changed by 1932 in the Baedeker (the built-up area of the city only extending to Hardstrasse). I haven't found useful documentary evidence of it's development subsequently, but I remember people who grew up in the 1950s remarking how much of the area was still fields. I believe that gradually individual plots were built over, but that it's progression to a completely urban landscape was piecemeal. Only ten years ago this plot was a field still cut for hay once a year. I don't know what preceded big developments like Letzipark or the huge number of UBS buildings in the area, but on the whole I suspect , like Aussersihl, it corresponds to type 1 in my classification, albeit with development occurring over a longer timespan.

I've looked at  three medium-sized Western cities, two whose development was driven by industry (Nottingham and Pittsburgh), with Zurich's growth more driven by commercial factors. None of these cities have suffered extensive damage from war or natural disasters. They have developed from a central core, rather than through the agglutination of several development nuclei, but have assimilated outlying areas as they have grown. I hope the outline of classification set out here may be useful for many towns and cities with similar histories of development. I'll return to the implications for the mapping of historical data in the context of OpenStreetMap at the end of this series of posts.