A pneumatic tube counter counts axles, and two tubes a metre apart give a speed and a length. Ours, on a private lane locked at both ends from dusk, records one two axle vehicle at about thirty miles an hour, southbound, at twelve minutes past three, most nights.
I manage a private estate and the lane through it is mine to look after.
Why there is a counter on it.
The lane is a right of way for the four properties on it and nobody else. It has a gate at the top and a gate at the bottom, both locked from dusk to seven with a code, and the code is known to the four households and to me.
In 2019 there was a dispute about the lane's use and its upkeep, and the fairest way to settle it was to count. So I hired a counter: two pneumatic tubes across the tarmac, a logger on a post, an axle count with time and speed and direction for a month.
I have kept one there since, because the data settled the argument and because it is cheap.
At twelve minutes past three, most nights, the counter records one vehicle.
Two axles, about two point seven metres apart, which is a car. Southbound, from the top gate towards the bottom. About thirty miles an hour.
Both gates locked.
The gates are not bypassable by a car. They are field gates on stone piers, with a ditch either side and a hedge, and the ditch is deep enough that I have had a quad bike in it.
The gate locks log their opening, because they are keypad locks, and the log shows the last opening at about half past ten and the next at seven, on every one of those nights.
What has been checked.
The counter. Hired from two companies, three different units, tubes replaced, and one unit with a radar sensor instead of tubes, which sees a vehicle rather than feeling one.
The radar saw it too. Same time, same speed, same direction.
The four households. All four have been asked, kindly, and none of them has a car out at three, and all four have cameras on their drives that show their cars where they were left.
Wildlife. A deer will trip a tube. A deer does not trip two tubes two point seven metres apart in the pattern of two axles at thirty miles an hour, and the radar does not classify a deer as a vehicle two point seven metres long.
What the counter shows that a person would not.
Speed. Thirty miles an hour on that lane is not something the four households do, because the lane is narrow with a blind bend, and the day count shows them at about fifteen.
And the axle spacing. I have the spacing on every night to the centimetre and it is the same, within the tube's precision. Not a car of that kind, the same car, going the same speed, at the same minute.
The bottom gate, which is where the lane ends.
A southbound vehicle at thirty passes the counter and reaches the bottom gate about four hundred metres later, in about thirty seconds. The gate is locked and the lock logs nothing and the gate is undamaged and the lane ends.
I put a second counter at the bottom, twenty metres before the gate, in 2022.
It records nothing. The car crosses the top counter at twelve minutes past three, at thirty, southbound, and it does not arrive at the bottom counter, and there is no turning between them, and there are no gaps in the hedge.
What is done about it.
The night count is excluded from the lane's figures, which are what the maintenance costs are shared on, and nobody has objected because nobody is being charged for it.
I have mentioned it to the local police, once, in the context of poaching, and they were polite.
What I do.
I download the counter monthly and I keep the files.
The one change is that I do not walk the lane at night.
I used to. It is a pleasant lane and I live at the top of it, and a walk to the bottom gate and back before bed was a habit.
In October 2022 I was walking down it at about ten past three, because I had not been able to sleep and because I had decided I would stand at the counter when it happened.
I stood at the counter. At twelve minutes past three both tubes clicked under my feet, twice, the way they do when a car goes over them, and nothing went over them, and the air moved past me southbound, fast, the way it does when a car passes close on a narrow lane, and it did not touch me and there was nothing in it.