My comapny is currently looking into using RapidPlan by Invarion to produce traffic control plans. Has anyone used Infraworks for this purpose, or have some insight on what RapidPlan can do that Infraworks can't?
InfraWorks has no tools specific to traffic plans, so RapidPlan is going to be more, er, rapid.
There's nothing available yet but, if you want traffic analysis within Civil 3D, check out Project Commuter at Autodesk Labs. It currently doesn't have a working version that ties into InfraWorks but, that is what is being considered. Go there and give them your feedback. If no one asks for it, they won't do it.
Traffic simulation modelling tools like Commuter are intended primarily for the analysis of traffic movement. In the context of traffic control plans (a.k.a. traffic management plans) simulation modelling can be used to analyse the effect of a proposed plan - how is the performance of my road network going to be affected by this plan? Animated visualisation is one type of output, especially useful for communication to stakeholders; other outputs include Excel tables containing forecasts of delay, travel times, queue lengths, level of service, etc. The tables quantify the effect over the course of the days or weeks of the proposed construction or road works, perhaps through multiple stages of work. For smaller simpler work sites, simulation modelling may not be necessary, and even for larger, more complex sites, an experienced practitioner may have a pretty good idea what the effects will be. However, a simulation tool can provide a more tangible realisation of the consequences of the work through numeric data, and animation if required, both for stakeholder communication and as a decision aid in choosing between multiple alternative proposals.