projects header image - PCB and some wires

Reimagining the Turnstile

projects header image - PCB and some wires

Improving User Experience, Mitigating Infrastructure Injustice and Assuring Safety and Security for All

Published on .

As part of the Illinois Tech’s inter-professional projects (IPRO) program, I had an opportunity to do field research and learn about both user-experience and user-centered design. Under the instruction and supervision of Dr. Noah McClain and Hans Mickelson, my classmates and I built a prototype of an access-control system that sought to improve upon the high entry/exit turnstiles employed by the Chicago Transit Authority at ‘L’ stations throughout Chicago. My major contributions to the project included doing much of the literature review, compiling a document detailing our work over the course of the semester, creating and disseminating an “L” station usage survey, reviewing the survey results, and building and programming an Arduino powered, pressure sensitive grid that allowed the prototype to respond and adapt to pedestrian traffic.

What’s an IPRO?

Here’s what Illinois Tech has to say about these projects:

Illinois Tech offers an innovative and comprehensive approach to providing students with a real-world project-based experience – the integration of interprofessional perspectives in a student team environment. Developed at Illinois Tech in 1995, the IPRO Program consists of student teams from the junior through graduate levels, representing the breadth of the university’s disciplines and professional programs. The multidisciplinary IPRO team project course experience is offered via three platforms that provide students a variety of choices that tap their passion and disciplinary knowledge. IPRO projects also offer sponsors, community partners and other collaborators customized approaches to accommodate their interests. All three IPRO platforms are designed to achieve the same learning objectives and serve our undergraduate students in fulfilling their two-IPRO six-credit-hour general education requirement. At the traditional end of semester IPRO Day event, IPRO teams from all platforms exhibit their work for the semester, with variations in how teams from different platforms are evaluated. (source)

The Problem

Presently, the Chicago Transit Authority (CTA) employs two types of turnstiles in “L” stations. These turnstiles were designed according to normal anthropometric measurements taken from the US army in the 1970’s. As an unintended consequence of this choice, the turnstiles can be awkward and difficult to navigate for individuals who are not anthropometrically “normative”, who are traveling with children, or who are carrying luggage/bags. Additionally, the average body size for the top percentile has increased by 20% since those measurements were taken. Through field observations, survey research, iterative design, and a thorough review of the related literature, we set out to create a new type of access-control method to replace existing turnstiles, thereby increasing the accessibility and safety of “L” stations.

Team Members

(Listed in no particular order)


Layth Alaswald, Nadim Yachouchi, Mohammed Hatahet, Martin Majkrak, & Laura Amaro

The drawing team was responsible for operationalizing our design ideas and creating scale models in applicable softwares like CAD and SolidWorks.


Yuanfang Xiang, Josh Guberman, John Stoll, Dan Leitzke, Doug Wilhelm, Sydney Hardwick, Erick Perez

The electronics team was tasked with operationalizing the electronic components of our design, including any programming required to render these electronics functional.


Haoyu Yang, Kiki McNeil, Jeff Somerfield

The mechanics team was in charge of prototyping the physical barriers and the movable parts of our design.


A graphical representation of our access controll system</p>

My Contributions


Having identified potential problems with the current turnstiles, we created and distributed an online survey in order to gauge which issues were most important to the general public.

Data Collection

The survey was intended to build upon our field observations by obtaining input from “L” riders. It contained questions related to frequency of travel, physical mobility, traveling with bags or luggage, and overall experience with turnstile usage. To reach as wide an audience as possible, the survey was distributed on:

  • The IIT admitted undergraduates facebook page
  • Twitter, where it was “retweeted” by @CTAFails
  • Reddit
    • /r/IIT
    • /r/chicago
    • /r/disability
    • /r/wheelchairs
    • /r/chibike
    • /r/samplesize
    • /r/research
    • /r/access
  • Tumblr
  • Craigslist

Data were collected over a three day period.

Survey Results


Through qualitative coding, we sorted the written responses into several categories:

Card read errors / Ventra 8
Too narrow 14
Difficulty with bags / luggage 20
Hard to turn / push 8
Inaccessible to wheelchairs 3
Physical injury 5
Damage to personal property 2
Not bike accessible 6
Gets stuck 14
Too high or low (waist-high turnstile) 2
No dedicated entrances / exits 4
Separates parents from children 1
Intimidating / scary / impersonal 6

Input From Reddit

From captainstardriver via /r/disability/

How about some sort of sensor, like an i-Pass for wheelchairs that triggers the gates and can just stick to the frame somewhere.

From GutterBunny via /r/chibike/

The main problem I have is being trapped behind the gates with my bike if an attendant is nowhere to be found. Washington blue line is a main problem.

From grendel_x86 via /r/chibike/

My big problem with taking a bike on the el is when I have it on the train, keeping it steady, and staying out of people’s way. Getting it into most stations, or up stairs is never difficult. Good luck with the project, turnstiles are a pretty old concept, and I can see changes having a big impact.

From jojofine via /r/chicago/

I liked the ones in London that were little doors that would open when you tapped your card

From mickcube via /r/chicago/

i think the turnstiles are actually pretty good. i like them better than some other more modern systems, for example paris

From mickcube via /r/chicago/

it’s more of a lack of things to dislike - it’s just a standard turnstile with an easy touch card system. touching a ventra card is easier than swiping a metrocard. in paris, the ticket readers often don’t work, and people can get stuck between the turnstile and the barrier. in london and boston, the doors can swing shut on your luggage. BART has those unsightly triangle things.

From mandrsn1 via /r/chicago/

I like the turnstiles they have in Tokyo. They stay open all the time. The gate only closed when a person tried to enter without putting in a pass. They were way more efficient.

From captainstardriver via /r/disability/

I have not taken the Chicago L specifically but the ideal arrangement for me, a person in a power chair:

  1. No fees/tickets/cards/etc. If you’re in a wheelchair you ride free.
  2. Because of #1, a simple gate for wheelchairs to go through at the turn-styles.
  3. End of story. I’ll give you that there will be abuse of #2, and even of #1 but let’s face it, it’s easier and the trade-off might be cheaper than trying to accommodate disabilities by rebuilding everything every few years because requirements change.

Operationalization of Floor Sensors (Proof of Concept)

Schematic for an individual velostatic tile
Schematic for single velostatic tile

We discussed using pressure sensitive floor sensors to determine both the necessary width of the thresholds and to determine whether or not someone was passing into the threshold without paying the fare. To accomplish the former, we confirmed that assisted machine learning would potentially make this concept possible. This entails feeding the system a very large number of pressure patterns and categorizing each pattern. Each category would correspond to a particular profile, each profile with a set width requirement. After being fed enough samples, the AI, theoretically, would be able to make decisions in real-time regarding the pressure distributions of live people traversing the ‘L’ station. Actually accomplishing this feat was far too time consuming, considering how far into the semester we were at this point. Instead, we decided to emulate it using Velostatic floor tiles that were not actually hooked up to the rest of the system and passive infrared (PIR) sensors to detect when someone was moving through a threshold without paying. If someone tripped the PIR beam without their fare being collected, the saloon-door barriers closed on the would-be fare-jumper. As for the tiles, we used a 2 x 2 grid. Each grid was wired through an Arduino to an LED. The LEDs varied in brightness according to the amount of pressure on a given tile. Using an Arduino Uno, bare copper wire, some resistors, and a lot of duct tape, I created a functional, pressure-sensitive 2x2 grid. Unfortunately, no one, myself included, thought to capture this on film. I do, however, have a proof-of-concept demo I made using a single small tile.

Proof of concept demonstration video for a single pressure-sensitive tile