Coordinate systems are the least glamorous line in a survey scope and the one that most often produces a deliverable somebody cannot use. This picker turns the decision into three questions and gives you a reference string you can paste straight into a scope of work.
It is a scoping aid, not a transformation tool. It tells you what to ask for; it does not convert data, and it does not replace a professional's judgement on a job with unusual requirements.
Nothing you select is stored or sent anywhere — this runs entirely in your browser. It is a scoping aid, not a transformation tool and not professional advice on a survey that requires a licensed professional.
The three questions, and why they are the right ones
1. What already exists
This one outranks everything else. If the site has a survey, a set of drawings, a design model or a GIS layer, the new capture should be delivered on whatever those are already on. Being independently correct is not the goal — being comparable is. A new survey that disagrees with the existing record is the one everybody will distrust, and resolving that argument costs more than the survey did.
Site grids are the most common way this goes wrong on Alberta industrial ground, because the transformation between the site grid and a published system usually lives in one person's file rather than in the data. If you are on a site grid, get that transformation in writing as part of the deliverable.
2. Where the work is
Location sets two things mechanically. The Alberta 3TM zone is whichever of the 111°, 114°, 117° and 120° west meridians your site sits nearest, and the UTM zone across Alberta is 11 west of 114° W and 12 east of it. Neither is a judgement call — but both have boundaries, and a project that straddles one has to pick a side and stay on it. Two contractors independently picking different zones for adjacent work is a real and recurring problem.
3. What the deliverable is for
Distortion tolerance is the difference. UTM's six-degree zones flatten a lot of curved earth onto a plane, so grid distances and ground distances differ by an amount that varies across the zone. For a stockpile volume that is irrelevant. For a long alignment where the drawings quote ground distances it is not, which is why 3TM's narrower zones dominate Alberta engineering and cadastral work. The 10TM system, centred on 115° W, shows up mainly in provincial resource and forestry datasets.
Elevations are a separate decision
Horizontal and vertical are independent, and a scope that names only the horizontal system is half-specified. The current Canadian vertical datum is CGVD2013; CGVD28 is the legacy one, and the difference between them is large enough to matter on a real job. If your existing site data is on CGVD28, say so, and say whether you want the new data on the legacy datum to match or on CGVD2013 with a stated relationship to it.
What this picker deliberately does not do
It does not determine boundaries. If the deliverable is a property line, a Real Property Report or anything registered at Land Titles, that is the reserved work of an Alberta Land Surveyor regardless of what coordinate system the data is in — see does a drone survey need a land surveyor's sign-off. It also does not handle datum epochs, which matter when comparing captures years apart at tight tolerance, or projects with a purpose-built low-distortion grid. Both are worth a conversation rather than a dropdown.