Office of Operations
21st Century Operations Using 21st Century Technologies

Efficient Use of Highway Capacity Summary
Report to Congress

Figure 35. Graph. Flow Impacts of Speed Harmonization—Germany.

Two side-by-side graphs comparing speed flow density curves on a facility with and without speed harmonization. On both graphs, the flow q (vehicles/hour/lane) and the y axis is speed v (km/h). The graph on the left — without speed harmonization — indicates a typical speed flow diagram where the flow begins to drop off significantly where the speed is 100 km/h and the flow is 100 vehicles/hour/lane. The distribution of points on the graph is fairly uniform until the speed drops to 40 km/h. The graph on the right — with speed harmonization — differs in that the majority of points on the graph are above 60 km/h. Fewer vehicles experience a flow rate below that when speed harmonization is active.