Light colored pavement has also proven to be problematic. During the field tests, several communication problems occurred between the data logger computers and VIP systems. These problems ranged from partial failures, which were detected by the VIP system and corrected by the operator, to total failures that resulted in an inability to record or retrieve usable data. Most of the communication problems were noticeable during the setup procedures. The systems were usually unable to recover from setup problems and needed to be reinitialized.
Additional work is needed to address power or system failures, data overflow, and system recovery.
While there are many areas requiring improvements, VIP systems appear to be ready for deployment to address specific detection problems for the limited siting and environmental conditions in which they have already demonstrated good performance. For speed detection, VIP systems can perform quite well. Occasionally a VIP machine will fail to detect a vehicle due to occlusion or lighting conditions, but on another occasion it may over-count a large truck. These errors tend to cancel each other out over longer periods of monitoring, resulting in a relatively accurate count. In all cases, deployment should be preceded by a detailed site investigation to ensure that the local siting constraints are recognized and that the installation will be able to handle the required task.