The bollard footing, worked from the hole rather than a rule
Concrete for a bollard is two separate volumes and the second one gets forgotten. The annulus is the hole minus the pipe that stands in it: a 16 in hole 3 ft deep is 4.19 cubic feet, and a 6 in pipe standing in it displaces 0.59, leaving 3.60. If the pipe is also cored solid, the core over 6.5 ft of total pipe is another 1.28 cubic feet. That is 4.88 per bollard, or nine bags at 0.6 cubic feet. Twelve bollards is over a hundred bags, which is a pallet and a half and not something to discover on the morning.
Whether to core the pipe at all is a question about what the bollard is for. An empty pipe deforms and stays standing; a cored one is stiffer and transfers more into the footing. Neither is universally right and the page does not choose.
The fencepost problem in the bollard count
A hundred and sixty feet of frontage at five foot centres is not 32 bollards, it is 33, because both ends need one. Getting this wrong by one is harmless; getting the reasoning wrong matters when the run is short, because a 15 ft frontage at 5 ft centres is four bollards and not three. The page adds the closing one, and the extras field is for the ones that are not on a run at all: the pair either side of a door, the one guarding a corner column, the ones round a gas meter.
Wheel stops are not free of consequences
They are cheap, they are fast to place, and they stop a bumper reaching a wall. They are also a six foot long, five inch tall obstacle lying in the path of anyone walking between rows, and they collect litter, ice and plough damage. Most lots put them only where something is actually at risk, which is normally a fraction of the stalls rather than all of them. The share field is set at a third for that reason, and the honest way to fill it is to count the rows that back onto something.
What one stall of hardware costs
With the defaults, the hardware comes to somewhere near a hundred dollars a stall all in, which is several times what striping the same stall costs. That ratio is the useful output. It is also the reason hardware gets value engineered out first and then added back after the first vehicle goes through a storefront.
Questions people ask
How many bags of concrete for a bollard?
Work it from the hole. A 16 in diameter hole 3 ft deep is 4.19 cubic feet; a 6 in pipe standing in it takes back 0.59; filling the pipe over 6.5 ft adds 1.28. That is 4.88 cubic feet, or nine bags at 0.6 cubic feet each. Change the hole diameter and it moves fast, because the volume goes with the square of the radius.
How far apart should bollards be spaced?
This page does not say, because the answer depends on what is behind them, what could hit them and how fast, and often on an insurer or a utility rather than the site plan. Get the spacing and the pipe and footing detail from whoever is requiring the protection, then put it in the field.
How many wheel stops does a parking lot need?
Only the stalls that back onto something a bumper should not reach: a walk, a wall, a planting strip, a drop. On a typical lot that is a third or less of the stalls, not all of them. Count those rows rather than applying a share, because the answer moves the material cost by a factor of three.
How many signs go on one post?
One usually, two where a stall sign sits under a designation panel. The page divides the sign count by the signs per post and rounds up. What must be on the post at an accessible stall, and at what height, is set by your permitting authority and not here.
Why is the hardware more expensive than the striping?
Because it is material and digging rather than paint and walking. With the defaults, hardware lands near a hundred dollars a stall against a fraction of that for line work. It is the first thing cut from a budget and often the first thing added back.