Rise and fall method
The rise and fall method is a technique used in surveying to determine the difference in elevation between two points. It is commonly used in design and construction to create accurate site plans.
A levelling instrument such as a dumpy level or a theodolite is set up at one point (the benchmark) and a staff is placed at a point whose elevation is to be determined. The instrument is then sighted on the staff and the vertical distance between the instrument and the staff is measured. This is known as the backsight.
The staff is then moved to the next point and the instrument is sighted on the staff again. The vertical distance between the instrument and the staff is measured once more, and this is known as the foresight.
If the foresight is higher than the backsight, it means that the point being surveyed is higher than the benchmark. The difference between the foresight and the backsight is known as the rise. If the foresight is lower than the backsight, it means that the point being surveyed is lower than the benchmark. The difference between the backsight and the foresight is known as the fall.
The process is repeated for multiple points, with the rise and fall measurements being added and subtracted as appropriate.
[edit] Related articles on Designing Buildings
Featured articles and news
Construction industry reactions to the election result
ECA, CIAT and more to come as published.
At a Crossroads; Pathways to a Net Zero Future
Background to and summary of this key Renewable UK report.
Installing solar panels on listed structures.
The current and future global market dynamics of boilers
Significant challenges but adaptation to sustain for longer.
Designing sustainability and performance into buildings
Specifying and selecting sustainable resilient timber products.
Modifying wood to improve resistance to decay and movement.
A last minute, long look for built environment professionals.
The architecture of creative reuse. Book review.
Sustainable development global goals, history in progress?
"Unless we act now, the 2030 Agenda will become an epitaph for a world that might have been."
Mike Kagioglou FCIOB named CIOB President
'Sustainable Development Goals must be focus for construction'
BSRIA training; a look at what's on offer
From energy management to compliance training.
TESP video warns to beware of rogue trainers.
Highlighting the slippery tactics of non-approved providers.
New Building Safety Wiki launched
Boosting awareness and understanding of the new fire safety regime.
New playbook on AI in construction published by CIOB
How to get to grips with, and the best from AI.
Digital Construction Report NBS
BIM, cloud, off-site, immersive tech, AI, twins and sustainability.
Comments
[edit] To make a comment about this article, or to suggest changes, click 'Add a comment' above. Separate your comments from any existing comments by inserting a horizontal line.