This paper looks at the junction capacity implications of using portable vs temporary signals under UTC control when undertaking junction improvement works. LinSig and VISSIM have been used to demonstrate the benefit of introducing temporary signals at more complex junctions by comparing capacity, journey times, delay, and queueing. Further analysis has been undertaken across a sample of some 20 junctions. This analysis provides a guide that will allow an Authority or client to determine the likely capacity implications of choosing one system over another dependent on junction type. It can form one input into the decision-making process which will also include, strategic importance of location, duration of works and costs.