360 least-cost paths, pre-solved over OS Terrain 50. Move a dial to
see which landscape factors have to matter for a given corridor to emerge.
Solved on a 20 m grid — 1.77 million cells, 14.1 million connections — over
BGS geology at 1:50,000. Cross-slope was tested and changes almost nothing, so
it is held fixed.
Opens at the preferred setting — climb 14, wet 20,
crossing 2000, descent prior moderate — analyst judgements, not model outputs.
Cost of gaining and losing height. Turning this up drives the
route into the valleys — it trades wet ground for gentler grades.
Charges soft going two ways and takes the greater, never both:
ground that is level and low, and ground on Gault clay or greensand
from BGS 1:50,000. Alluvium and peat are measured but not charged — they are
largely later than the question.
Charged per stream or river crossed. The strongest lever
here: from 13 crossings down to 1, and interfluve use from 17% to 46%.
New Town / Workway (N2) has a road drawn down the face on
Andrews & Dury 1773, a holloway with a 73 m drop on 1 m LIDAR, and usable
tracks on the ground today. Huish (D2) has only a minor, very narrow farm track. The prior
discounts N2 and surcharges N1 across a 600 m catchment on the descent, and
nowhere else.