Protected views

Or where I try and work out where a tall building is least likely to be sited.

At the planning consultation last week, the issue of protected views was raised by our table facilitator. I went away and did some research on this, digging out the relevant information from the GLA's website.

There are three protected views of the Tower of London, and more specifically, the White Tower, one from the middle of London Bridge, one from the south end of London Bridge (both on the eastern side) and one from the Queens Walk near City Hall (directly across the river). The last of these won't be affected by anything at the News International site.

Once again I was forced into the wacky world of cartography and different coordinate systems and mathematical models of plotting a flat map onto a sort of spherical world (or vice versa?). All of the viewpoints in the GLA documentation are based on a projection devised by the Ordance Survey, and locations specified as Eastings and Northings which measure distance in metres from somewhere in the Atlantic. So, not only do Eastings and Northings need to be converted into degrees, they then need to be corrected onto the same projection as used by Google Maps.

What I've done is plot the specified sightlines onto maps as red lines that follow the bearing specified by the GLA. I've then calculated zones either side of the sight line +/- 2.5 degrees either side and then a second zone of an extra 2.5 degrees either side, which are coloured red and yellow respectively on the map below. A word of caution, even after the corrections I've applied, I don't know if the projection is correct - the GLA state that the lines should go over one of the corners of the White Tower- this though depends on the satellite imagery matching to the mapping data.

What the map clearly shows is that it is the northwestern corner of the site which is likely to be the most sensitive to having a tall building placed there, which increases the likelihood of any tall structure going to the south of the site. In my opinion a tall building would sit best near Thomas More square to maintain a cluster of tall buildings, the further east the building goes, the taller it can be built and be hidden behind Thomas More Street.

My next project therefore must be to work out the height of the buildings at Thomas More Square, the height of the land at Thomas More Square and the News International Site and the relative height of London Bridge to do some trigonometry to work out how tall a building they can get away with.