Sub-Zone road length error

If I draw a test rectangle (as shown) and then use Google ruler to measure it I find a width of 936 m and a length of 2.368 m. This gives an area of 2.216 km2. I set this area to a default residential area. If it has an average block size of 100m then the length of secondary roads in the rectangle will be 22.16 km However TAMT calculates it to be 45.4 km. Additionally TAMT assigns this length to Industrial and commercial areas which are not even included in the Test rectangle and thus should have been zero.

Please note that the road length calculation in TAMT (see above) is correct in 
this case. It should be 45 km (based on area divided by average block size and 
multiplied by 2). If I then define a sub-zone within this rectangle of approx 
half its size and assign to Industry, TAMT gives a road length in the Industry 
sub-zone of 32.78 km, but it has an area of approx 1 km2 and a block size of 
170 meters which would give a road length of  1 km2 / 0.17 * 2 = 11.7 km not 
32.7. Please note that by defining this industrial subzone the residential 
default zone should be reduced in size and the road length in the default 
residential zone should now be approx 1.2 km2 / 0.1 * 2 = 24 km. However TAMT 
reports it as unchanged in 45.4.

Original comment by jarogers...@gmail.com on 21 Jul 2011 at 4:30

Attachments:

lijian8 / tamt

Sub-Zone road length error #75