Case Study : Environmental Safety Monitoring System For Sidewalk

The Bureau of Engineering of the City of Los Angeles maintains over 7,500 miles of sidewalk. When a slab of concrete on the sidewalk does not settle evenly or has been raised up because of tree-root growth, the slab is not even with the neighboring slabs. This can cause pedestrians to stub their toes or even trip and fall, leaving the city open to damages. In addition, the city is obligated to maintain its sidewalks in conformance to federal standards, which limit sidewalk slope to no more than +/- 2% relative to the street. Currently, the Department measures sidewalks using manual level-measuring tools. This process is labor intensive and cannot be effectively scaled to the city's 7,500 miles of sidewalk. In this work we develop a semi-automated IoT-based sidewalk monitoring platform to effectively monitor the sidewalk condition. The Edge portion of the platform—Edge in IoT terms—is composed of a Raspberry Pi 3 B+, an accelerometer, a gyroscope, a camera, and a GPS module. We use the accelerometer and gyroscope to measure the sidewalk slope, the camera to take images of the sidewalk, and GPS module to collect location data. The collected data is saved in the on-board memory of the Raspberry Pi. Upon returning to a base station, the collected data is uploaded to the City Cloud server using Apache NiFi and MiNiF. Users can then examine the slope and image data. In addition, while collecting data in the field, the staff can view the data collected in the Raspberry Pi using the web-app installed on a mobile device such as a phone or a tablet. If the Internet connectivity is available on the mobile device, the collected data is uploaded to back-end server in the field. Otherwise, we use ad-hoc network to communicate with Raspberry Pi. Experiments have demonstrated the feasibility of the design and implementation of the Edge data collection platform.