Creating analysis tools for measuring the performance of park and ride lots and assessing how they impact the rest of the transportation system is needed and requires a national perspective.  Formula-based models estimating park and ride demand that predict carpool and vanpool users exist, but these models are out of date and they DO NOT include transit capacity.  This leads to underestimated levels of demand, which result in poor planning and designing of park and ride facilities.  The end result is the funding of park and ride lot improvements at levels far below those needed to maximize highway capacity and system performance.  Even when states want to do the ‘right’ thing—reduce vehicle miles traveled (VMT), reduce greenhouse gases, and reduce energy usage, they lack the validated methodology and tools to support facilities, such as park and ride lots especially near high occupancy vehicle lanes, required to meet these goals.  Many states have made huge investments in these facilities, and future demand is expect to continue to rise, but we do not know how and where to predict that demand adequately.  Develop tools to analyze the demand for park and ride lots and assess the impact they will have on the performance of both transit services and the roadway network at both the planning and the project development levels.  Also, determine general benefits of park and ride lots on the performance of transportation facilities to ensure transportation agencies understand the value of including these facilities in all improvement programs.