[Paper Review] Mobile Safety Application for Pedestrians

Şükrü Yaren Gelbal, Mustafa Ridvan Cantas+4 more|arXiv (Cornell University)|May 27, 2023

Vehicular Ad Hoc Networks (VANETs)4 citations

TL;DR

This paper proposes a mobile safety application that leverages smartphone sensors and Bluetooth 5.0's long-range mode to broadcast Personal Safety Messages (PSMs) compliant with SAE J2735, enabling Pedestrian-to-Vehicle (P2V) warnings. The system enhances pedestrian safety in no-line-of-sight and low-visibility conditions by providing drivers with early collision warnings, significantly increasing reaction time at intersections.

ABSTRACT

Vulnerable Road User (VRU) safety has been an important issue throughout the years as corresponding fatality numbers in traffic have been increasing each year. With the developments in connected vehicle technology, there are new and easier ways of implementing Vehicle to Everything (V2X) communication which can be utilized to provide safety and early warning benefits for VRUs. Mobile phones are one important point of interest with their sensors being increased in quantity and quality and improved in terms of accuracy. Bluetooth and extended Bluetooth technology in mobile phones has enhanced support to carry larger chunks of information to longer distances. The work we discuss in this paper is related to a mobile application that utilizes the mobile phone sensors and Bluetooth communication to implement Personal Safety Message (PSM) broadcast using the SAE J2735 standard to create a Pedestrian to Vehicle (P2V) based safety warning structure. This implementation allows the drivers to receive a warning on their mobile phones and be more careful about the pedestrian intending to cross the street. As a result, the driver has much more time to safely slow down and stop at the intersection. Most importantly, thanks to the wireless nature of Bluetooth connection and long-range mode in Bluetooth 5.0, most dangerous cases such as reduced visibility or No-Line-of-Sight (NLOS) conditions can be remedied.

Motivation & Objective

• To address the rising number of vulnerable road user (VRU) fatalities through real-time, mobile-based safety warnings.
• To leverage smartphone sensors and Bluetooth 5.0's long-range capabilities for reliable pedestrian-to-vehicle (P2V) communication.
• To implement a PSM-based warning system compliant with SAE J2735 standard for interoperable V2X safety messaging.
• To improve driver reaction time by delivering early warnings in challenging visibility or obstructed line-of-sight scenarios.
• To demonstrate the feasibility of using consumer-grade smartphones as active safety nodes in connected vehicle ecosystems.

Proposed method

• The system uses smartphone sensors (e.g., GPS, accelerometer) to detect pedestrian movement and intent to cross.
• It generates and broadcasts Personal Safety Messages (PSMs) using the SAE J2735 standard for V2X communication.
• Bluetooth 5.0's long-range mode enables reliable message transmission beyond line-of-sight (NLOS) conditions.
• The application sends warnings to nearby vehicles via Bluetooth, allowing drivers to receive alerts on their mobile devices.
• The PSMs include location, speed, heading, and status data to support accurate risk assessment by receiving vehicles.
• The system operates without requiring dedicated roadside units or infrastructure, relying solely on mobile devices.

Experimental results

Research questions

• RQ1 Can smartphone-based PSM broadcasting via Bluetooth 5.0 effectively reduce pedestrian-vehicle collision risks in no-line-of-sight scenarios?
• RQ2 To what extent does using standard-compliant SAE J2735 PSMs improve interoperability and reliability in pedestrian safety applications?
• RQ3 How does the integration of smartphone sensors and Bluetooth 5.0 enhance early warning delivery compared to traditional methods?
• RQ4 What is the performance of the system in low-visibility or obstructed environments where visual detection fails?
• RQ5 Can consumer-grade mobile devices reliably serve as active safety nodes in a P2V safety communication framework?

Key findings

• The proposed system successfully enables P2V safety messaging using only smartphone sensors and Bluetooth 5.0, eliminating the need for dedicated infrastructure.
• Bluetooth 5.0's long-range mode allows reliable message transmission in no-line-of-sight (NLOS) conditions, a key challenge in pedestrian safety.
• The system provides drivers with early warnings, significantly increasing reaction time before potential collisions at intersections.
• The use of SAE J2735-compliant PSMs ensures standardization and compatibility with existing V2X communication frameworks.
• The solution demonstrates feasibility for real-world deployment using off-the-shelf mobile devices, enhancing accessibility and scalability.
• The integration of mobile sensors and wireless communication enables robust safety warnings even in low-visibility environments.