Accurate knowledge of the impact of highway tolls on traffic demand responses is vital for both financing roadway construction and estimating the benefits of infrastructure improvements. Managing expressway congestion in urban areas is a major challenge for transportation planners, and also requires insight into drivers' responses to toll price changes. This study evaluated the short-term effects of highway toll reform, introduced for urban expressways in metropolitan Tokyo in April 2016, on the distributed traffic flow. We constructed distributed traffic flow models with panel effects using aggregated traffic volume data from the electronic toll collection system, and the effect of the toll reform scheme resulting from toll changes was confirmed statistically. We also estimated toll elasticity and confirmed that the results are similar to previous findings.