Intro: Mobile Speed Bump
With the advent of machine learning in “smart” environments and autonomous robots, our every move and every need will soon be anticipated by some other intelligent thing. We will no longer have to pay attention or wait around as we fluidly move through time and space. In this not-so-future world, slowing down will become increasingly more difficult. Enter: Mobile Speed Bumps.
The Mobile Speed Bump is a pause-to-go; a traveling interruption; a rest in the fast-paced rhythm of our everyday lives. In the midst of the widespread digitalization of our physical world, bumps provide moments of material respite.
There is no wrong place for a bump: multiple bumps can be arrayed on a crowded sidewalk, or just one can be left at your front door(a bump can be a great way to invite guests into your home). A bump can slow the cadence of a trafficky area or simply set the time signature of a scale-less space.
In this guide, we will review the design and fabrication of Mobile Speed Bumps so that you, too, can take it slow.
Step 1: Bump Design
The most fundamental thing to decide when designing a bump is how big it is going to be. The proportions of the bump will dictate its spatial performance, how people will interact with, and who its audience will be. For example: shallow bumps might be used for children or in circumstances where several bumps might be arrayed in secession; a wide bump could be used to slow several people at once; a bump that is vertically-oriented might become an obstacle that one can only move around. When designing a bump, the designer should consider the bodies of those the bump will be bumping and how the body of the bump relates.
Another important proportional constraint of the bump is its mobility. Whether or not the bump will be moved depends, in part, on whether one person can carry it. A bump might require several people to move it and then might be mostly sedentary, except on the occasion of a collaborative moving effort. The mobility needs to be designed into or out of the thing itself.
Mobility is significantly affected by the material of the bump. Though it is most common to see a bump made from concrete, they could also be made with other lightweight, environment-friendly materials or materials that have other architectural effects. For example, a bump could be made from earth so that it disintegrates into the ground from which it came, or it could be made from a transparent material so that it blends into its environment. The material of the bump will determine its weight and, thus, make it more or less mobile.
If a bumper chooses to cast their bump from a heavy material, e.g. concrete, then he or she should consider ways to reduce the overall weight of the bump by casting voids or lighter materials into the core of the bump. Similarly, if the bump is exceedingly large and/or heavy, the bumper should consider a method of physical reinforcement that is appropriate to their chosen material system.
The most important part of bump design is the handle. The handle is the way the bump gets passed from one bumper to another. It is what distinguishes a mobile speed bump for human beings from just another bump. In choosing or crafting the handle, the bumper can instill a unique expression into the bump so that even though it might move on to another bumper or another place, the object can remain identifiably their own. The design of the handle simultaneously represents the hand of the designer and the acknowledgement of the hand that will engage with the design.
Step 2: Preparing the Formwork
a) Build a three dimensional frame using the 2x4’s and screws. The interior dimensions of the frame should be the length, width, and height of the bump, respectively. Reinforce the outside of the frame as necessary to resist the weight of the concrete pour but ensure that one face is left free—this is where the fabric will go.
b) Measure the fabric out. The length of the strip should be equivalent to the length of your bump and the width should be the height of your bump multiplied by pi.
c) Align the edges of your fabric with the edges of your frame(all of the excess fabric should be gathered within the frame). Staple the fabric around the perimeter of the top portion of the frame. Do not leave more than two inches between staples.
d)) At the top of the frame, on top of the fabric, screw (2) 2x4’s equidistant from the midpoint of the length. The length of the 2x4’s should be the width of the frame. The distance from the midpoint will be determined by the center-center dimension of the mounting holes on the door handle(distance from midpoint = center-center/divided by 2).
e) Drill out one hole from each 2x4. The size of the hole will be determined by the diameter of the steel rod.
f) Insert one steel rod into each hole. Mark where the steel rod lands on the surface of the fabric and cut a hole with the scissors. Continue pushing the steel rod through the fabric. Seal the intersection of the fabric and the steel rod with tape.
Step 3: Pouring the Mix
a) Calculate the volume of your bump and determine how much concrete you will need—20 pounds of mix yields 0.15 cubic feet. Add this to one mixing bucket.
b) The amount of water you will need is one third the amount of concrete in weight. Add this to another mixing bucket.
c) Slowly add the concrete to the water while mixing. Continue adding and mixing until the concrete has achieved a pasty consistency.
d) Slowly pour the concrete into the formwork. Do not pour only in one place. Instead, evenly distribute the pour across the fabric surface. Lightly shake the formwork as you are pouring to eliminate air bubbles and ensure even settling.
e) Let the concrete cure for no less than 30 hours.
Step 4: Demolding the Bump
a) Once the concrete has cured, remove the steel rods and their 2x4 mounts from the top of the formwork.
b) Gently rip the fabric from the staples and remove the bump and fabric from the frame.
c) Flip the bump upside down—the side without the fabric should be facing down—and place it on a flat surface.
d) Slowly peel off the fabric. If a piece of concrete comes with it, then the mixture still needs time to cure.
e) Once the fabric has been removed, let the bump sit for another 3-4 hours to allow residual moisture to dissipate.
Step 5: Securing the Handle
a) Screw the threaded rods into the mounting holes of the door handle.
b) Place the rods and door handle into the voids by the removed steel rods. The door handle should be on the curved side of the bump.
c) Attach the washer and nuts on the other side of the bump. Use a wrench to ensure the washers are tight against the surface of the concrete.
d) Test that the handle is secure by lifting the bump.
Step 6: Bumper Certification
The aim of this project is to build an open source network of bumps: anyone can make a bump, take a bump, or make a bump their own. To become a Certified Bumper, leave your bump for someone else to take.