Transportation systems management is a set of techniques used to increase the capacity of a piece of transportation infrastructure without increasing its physical size. Most often, these techniques are used in the context of roadways. In this context, transportation systems management techniques may include changes to traffic signals, such as coordinating them or introducing ramp metering, or minor changes to road geometry, such as straightening corners or lengthening merge lanes. These low-cost interventions can be very effective in reducing congestion under some circumstances.