Federal Railroad Administration strictly regulates the inspection frequency of all track classes to ensure timely identification of rail defects including irregular gage which is a devastating rail geometry defect. Conventional rail inspection methods are both costly and labor-intensive, whereas existing novel technologies can be expensive and mostly focus on a specific inspection area, e.g. vertical alignment. iPhone 12 Pro was introduced to the public recently with a low-cost, low-resolution light detection and ranging (LiDAR) sensor that is purposed for better photography and virtual reality. Thanks to its portability and computational capacity, iPhone 12 Pro can potentially be used as a portable solution for irregular gage inspection, whose capacity and feasibility are unknown. This study first investigated the capability of the iPhone 12 Pro in calculating unloaded rail gages by its embedded LiDAR sensor. The results showed that uncalibrated raw gage values measured by the iPhone 12 Pro LiDAR sensor were systematically lower than the ground-truth values. The proposed method in this study then introduced logistic regression to calibrate the measured values through balancing the prediction performance and the efficiency, followed by validations using a Gaussian process classifier. The results show that the proposed method correctly identified all 39 high-risk locations with 227 false alarmed locations. The proposed method with the iPhone 12 Pro LiDAR sensor could potentially narrow down the possible “high-risk” gage sections and may result in a significant reduction in the field inspection workload by 48%.

联邦铁路管理局严格规定了所有轨道等级的检查频率，以确保及时识别铁路缺陷，包括不规则轨距，这是一种毁灭性的铁路几何缺陷。传统的铁路检查方法既昂贵又费力，而现有的新技术可能很昂贵，并且主要集中在特定的检查区域，例如垂直对齐。iPhone 12 Pro 最近向公众推出了一款低成本、低分辨率的光探测和测距 (LiDAR) 传感器，旨在实现更好的摄影和虚拟现实。由于其便携性和计算能力，iPhone 12 Pro 有可能被用作不规则量具检测的便携解决方案，其容量和可行性未知。本研究首先调查了 iPhone 12 Pro 通过其嵌入式 LiDAR 传感器计算空载轨距的能力。结果显示，由 iPhone 12 Pro LiDAR 传感器测量的未校准原始仪表值系统地低于地面实况值。本研究中提出的方法然后引入逻辑回归以通过平衡预测性能和效率来校准测量值，然后使用高斯过程分类器进行验证。结果表明，所提出的方法正确识别了所有 39 个高风险位置，其中 227 个误报位置。使用 iPhone 12 Pro LiDAR 传感器提出的方法可能会缩小可能的“高风险”量具部分，并可能导致现场检查工作量显着减少 48%。