Arlington High School InvenTeam
Pedestrian alert system
In Arlington, Mass., there are many intersections without controlled crosswalks, and many pedestrians have been struck by vehicles at these locations. The Arlington High School InvenTeam decided to create a system to enhance the safety of pedestrians at uncontrolled crosswalks. They devised an alert system to show the drivers when pedestrians were crossing and indicate which way they were going. The invention features two important components: the activation system and the light sequencing system. The activation system uses a piezoelectric cable as a pressure sensor to detect the weight of a person on the sidewalk, as he or she approaches the crosswalk. The weight on the piezo cable creates electrical energy and triggers a programming stamp that controls red-orange luxeon emitters, which are bright, inexpensive LEDS (light emitting diodes). The emitters signal the direction from which the pedestrian enters the crosswalk. They are illuminated for 15 seconds and then flash three times before they shut off. The Arlington High School InvenTeam originally planned to use a pole on either side of a crosswalk entrance to detect motion and trigger a light sequence. After extensive research, the students discovered this idea was patented, which set them back in their process. However, using their researching and problem solving skills, the team discovered the benefits of using piezoelectric cables. These cables worked better than the motion-detecting poles, and cost less. The team also had to select a type of lighting, which was imperative because many accidents were caused by poor visibility at night. The students chose LEDs, because they were cost efficient and long lasting. They also used flashing bumps or reflectors known as “flumps” to line the crosswalk. The team created a program for the lighting sequence using PBASIC, a version of BASIC programming language. The students spent a lot of time learning about and creating circuits during the process. The students received support from the Arlington Transportation Committee and the Arlington Traffic Advisory Counsel (TAC). Before the team began creating and implementing their invention, they spoke with the Arlington TAC to ensure that it met city regulations. The TAC was also able to connect the students with helpful people and companies within the community. The team spoke with representatives from many companies that manufactured products needed for the invention.