"If you move along Marozia's compact walls, when you least expect it, you see a crack open and a different city appear. Then, an instant later, it has already vanished. Perhaps everything lies in knowing what words to speak, what actions to perform, and in what order and rhythm; or else someones gaze, answer, gesture is enough; it is enough for someone to do something for the sheer pleasure of others: at the moment, all spaces change, all heights, distances; the city is transfigured, becomes crystalline, transparent as a dragonfly."
Italo Calvino: Invisible Cities
Bump creates a gap in the urban interface, a spot that provides no firm ground underfoot. Duckboards on the asphalt - an excavion perhaps? Suddenly a pounding sound is heard from below, the boards are rising, there is another city down below, mirroring the one above ground, connected with it by a data line. What is happening down there? An indifferent jostling crowd, the trampling of hundreds of feet - is it rush hour? In comparison, a late night scenario: two pairs of feet, three pairs of feet.
A rhythm is perceptible. Perhaps it contains a message? Or is it just a game?
We fall victim to the illusion of proximity: underneath the rising board we suspect a power similar to our own. But what is there is the machine, the piston, the relais, the sensor. The elementary experience of sensing leads to a natural feeling for distance and proximity, yet bump turns proximity into an illusion. The distance is not canceled out. The thin spruce board resembles a wall, hundreds of kilometres thick. In the end however it is more permeable than the screen, the window to the world, thinner than the projection surface of unmeasurable dimensions on which appears the image of a city. bump as a communication machine produces a tactile version of an impression, it makes tracks perceptible.
In each of two cities a footbridge, 15 metres long and 1.5 metres wide, and containing 75 step elements,
will be erected. If a person steps on one of these footbridges, their body weight sets off an impulse which
is then transmitted to the other city via data transmission. There a pneumatic piston raises the
corresponding board for about 1cm. A passenger takes notice because of the pounding sound of the pistons,
sees the boards move and, on entering the footbridge, feels the distant step of a person in a different city.