The lot is usually what puts the question in your head
Most people asking this are looking at the same picture. The pour sits above the road, or above the drive, and there is a bank between the two. A truck can get to one and not the other. In this part of Virginia that is not a hard site, it is a normal one. Lots along the Blue Ridge rarely hand you a flat, straight shot at the forms.
A chute cannot help with that, because a chute places concrete only where gravity and the truck allow. A line pump pushes instead, so the slope stops deciding where the concrete can end up. What decides it is where two people can walk hose.
The climb costs pressure, and so does everything else in the route
Inside the machine a piston pushes concrete into the line. Everything the concrete meets on the way out resists that push. The hose wall resists it along the whole run. Every bend resists it. And every foot the concrete has to climb adds the weight of the column standing above it to the total.
None of those are separate problems. They add into one figure the operator watches on a gauge and hears in the note of the machine. A short climb on an otherwise open route is nothing at all. The same climb at the tail of a long run with several turns in it is a different pour, and it gets laid out and paced with that in mind.
It is also why the layout is built before any concrete is on the road, with bends kept long and sweeping. A hard kink at the top of a bank is exactly where a line packs up, and a blockage found in the middle of a pour costs everybody standing there their morning. Nothing goes down a dry line either. A priming slurry runs through first to coat the inside of the hose, and on a climbing route that coat matters more rather than less.
Where the trailer sits when the pour is above the road
The trailer wants firm, reasonably level ground with room for the mixer to back up to the hopper. Those two needs usually keep it down at the drive or on the shoulder, which means the concrete does the climbing and not the machine. That is the normal arrangement here and it works.
Sometimes the better answer is the other way around, with the trailer taken up to a flat spot near the forms so the climb is short and only the ready-mix truck stays below. Whether that is possible comes down to whether a truck and trailer can get up there, sit level and turn around again. It is a question for the site walk, not for the phone.
Weight is part of the same decision. Empty pump hose is a two person carry. Full of concrete it stays exactly where it was laid, and on a bank that means the route is settled before the first yard goes in rather than adjusted while trucks sit on the clock.
Runs that fall away instead of climbing are easier on the machine, though they are not free. Concrete heading down a grade wants to move on its own, so control at the placing end is what gets watched instead of pressure at the hopper, and the pace comes off what the crew can screed.
Describe the grade when you call, not the square footage
What helps on the phone is the shape of the route. Where a truck and trailer can sit. How far it is from there to the forms. How much of that distance climbs and how steep it gets. Whether there is a wall, a set of steps or a fence line to cross on the way up.
From that we can tell you what the layout is likely to take and whether the pour suits the line. We will also tell you when the truck backs right up to the forms and you do not need a pump at all. That happens more often than people expect, and when it is true it is the cheapest way to place concrete.