The relationships between instantaneous space-variables and (easily measurable) local time-variables in largely homogeneous and stationary traffic flow, as typically encountered in uninterrupted traffic conditions, are briefly reviewed. An elaborate analysis and microscopic simulation investigation is conducted with respect to the same relationships at signalized links with inherently strong traffic flow variations triggered by traffic signal switchings. A number of influencing factors when estimating space-variables from measured local time-variables is analysed and illustrated in detail. (c) 2007 Elsevier Ltd. All rights reserved.