Stairs are harder to walk, and higher risk of injury than slopes (imagine falling from stairs versus falling from slope).
So why aren’t slopes used more commonly in buildings?
Even stairs-shaped escalators are more common than slope-shaped escalators.
**Edit:** By “slopes”, I mean “ramps”. Pardon my English.
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TL;DR
Stairs are more space efficient than slopes, however we can only make slopes so steep due to accessibility. Generally speaking a step on a stair is 15cm high and 30cm deep (1:2 gradient) and a slope can at most be 0,5m high over 6m lengthwise, then you have to have somewhere to rest that’s 2m long and has a maximum slope of 2% (4 cm incline/decline over 2m). So arguably in buildings, it’s required space that’s the problem, therefore stairs and elevators instead of slopes.
Hopefully it cleared up some part of the question. I don’t know about escalators, but I would hazard a guess it’s about required space there as well.
I work as a civil engineer, designing roads, courtyards, football fields and other such things in Sweden so this might not fit a 100% of the time in all other countries but I believe most of the time it will. Generally if it’s outside and if it’s in the ground, I could be working on it making a drawing for the production side. So not inside of buildings, but the same generally goes when it comes to stairs and slopes.
You usually go for a slope when you have to make it accessible for people who might find it difficult to get up stairs for instance if you’re in a wheelchair. Now we can’t make the slope too steep because that would be an issue as well. There’s some rules and regulations that says that the most we can do slope to keep it accessible is 1:12, so 1 meter in height over 12m distance. However, the most we can do in one slope is 0,5m in 6m, but the gradient is still the same and after that we need a sort of flat surface for 2m, it can at most have a slope of 2%, so 4cm incline or decline on that “rest area” before you can do another slope or if you want to have a surface that’s 3%.
So what it sort of boils down to is that as long as we don’t have a slope that’s more than 2% we can go on forever essentially, but if it happens to be ‘steeper’ than that then every 0,5m of height we need to have a 2% slope for 2m as a form of rest area (best way I can describe it).
A step in contrast is usually 1:2 in its gradient. A normal step is about 15cm high (15-17cm) and 30cm deep (30-34cm) keeping the same gradient as 1:2. So it’s more space efficient to make stairs instead of slopes. Granted there are some stairs that we as humans might find strange or weird which are way deeper but only say 10-15cm high, we find these annoying to walk up usually because the stride length does not fully match with the effort and step depth.
Looking at cars and trucks (which of course doesn’t have stairs but you have to have some kind of gradient rules with those as well) we have a ruleset for those as well, depending on what type of road it is, in regards to how many vehicles will go down this road on average per day and what’s the purpose of this road, to get traffic in and out of a city center or a service road in the middle of nowhere?
So for roads you normally don’t want to go over 5% incline, but you can go up to 8% and in some cases you can go up to 12% but that will be very steep and in certain situations if there’s a pulley system for trucks, you could have it steeper perhaps up to 14%.
And as a final reference, we usually for roads have a slope on the side of the road that’s in grass and those are generally drawn with 1:3 (so 1m elevation over 3m length) but they can be done with 1:2 – 1:4 as well, these are the most common ones. There’s always some exception to the rule so to speak, but now you might have a general Idea of how it all sort of comes together.
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