Cambridge Underground 1990 p 24

Cave Survey of 161 Kaninchenhöhle

by Daniel Mace

This year a special effort was made to produce an accurate survey of the cave. The cave was completely resurveyed from the entrance. Only Adrian's Route, which was not descended this year, was not resurveyed.

Survey teams consisted of two or three people. One person took notes; the others read the instruments and decided where to place survey stations. A centre line survey was conducted by measuring the distance, compass angle and inclination between two points. Adjacent points had to be visible by a direct line of sight and were usually chosen on opposite walls so that the centre line would yield information on the passage sizes.

A leap frogging technique was used; ie. the first survey leg was measured descending the cave (eg. from station 1 to station 2) and the next leg would be measured in the opposite direction (from station 3 to 2). This helps to reduce zero errors in the compass and clinometer.

At each survey station, passage heights, widths and the height of the survey station above the floor were noted. Sketches of plans and elevations were made. Cross-sections were drawn at points where there was a major change in passage shape.

The measurements were recorded on permatrace film using a soft pencil. Whilst underground, the permatrace was protected from water and abrasion in metal binders. All the notes were still legible on return to Britain. 25m Rabone Chesterman tapes were used. All distances were measured to the nearest five centimetres. Suunto sighting compasses and clinometers were used and all angles were measured to the nearest half degree. In 1988 some problems were experienced due to the compass and clinometer misting up once underground in the cold, damp atmosphere. These problems were solved by drying the instruments in a vacuum desiccator for several days and then resealing them with a modelling glue before departing for Austria.

After the underground survey was complete, the note taker wrote up the notes in a survey book at base camp. This was carried out as soon as possible after the surveying trip. The polar measurements taken underground were converted to cartesian (x,y,z) co-ordinates using a programmable calculator and plans and elevations were drawn in Austria.

On return to the U.K. the data were recomputed. The many closed loops in the survey allowed calculation of errors and these were distributed evenly around the loops. With the exception of the Olympus series, the errors lay between 0.5% and 1.75%. Data computation was carried out by Wookey, Mark Dougherty and Keith Millar with the aid of the 'Cave Surveyor' program by Sean Kelly. The program also drew a centre line plan and elevation at a scale of 1:500.

The walls and passage details were then drawn on the the centre line elevation in pencil. The cross-sections were redrawn from the original notes on to graph paper, all at the same scale. The surveys were then traced onto tracing paper using Rotring pen and ink. The cross sections were traced on to the plan. The lettering for the survey was produced using an Apple Mackintosh and laser writer and glued onto the tracing paper. Invisible sellotape was used to stick down the edges. The survey was drawn by Wookey, Daniel Mace and the resident members of Cambridge University Caving Club.

The survey was photo-reduced slightly and photocopied onto A1 paper. Copies are available on request from Cambridge University Caving Club.