Large trucks have significant blind spots, and urban settings often bring these vehicles in close proximity to vulnerable road users (VRUs). Over 13% of VRU fatalities in Canada in 2016 involved collisions with heavy commercial vehicles. Transport Canada launched a multi-year field trial, in collaboration with municipal partners, to evaluate the state of VRU detection and warning technologies. The project evaluated cyclist and pedestrian alert systems retrofitted onto different types of heavy-duty commercial vehicles. Prior to the field trial, in-depth assessments were conducted on a test track to identify suitable systems for more extensive long term testing. The equipment had to accurately and reliably alert drivers of an imminent risk of collision, based on a time to collision warning, as well as limiting the number of false positive detections. Five different candidate systems were subjected to a series of simulated “urban environment” scenarios performed on a close track. The results of these tests are presented in this paper. The technologies included, ultrasonic, radar, 360 video cameras, smart cameras, and a combination of these systems. The test scenarios were based on the most common real world VRU-truck collisions identified from collisions investigation reports. Six dynamic and four false positive scenarios were created to test the capabilities of sensors designed to alert the driver of surrounding VRUs. Data were recorded on the timing of audio and visual alerts, the GPS position of the vehicle/VRU, the velocity and environmental conditions. All the detection systems were installed on a single vehicle, traditional cabin dump truck. Three test dummies were used: a 50 th percentile male, a 7 year-old-child and an adult cyclist. The results suggested that the current VRU detection and warning technology may not be sufficiently mature to fully address the risks. No single system could successfully warn the driver in time to avoid a collision in all of the test scenarios. The smart camera system performed best overall and was selected for more extensive testing on different vehicles in a multi-city field operational test.