With monitoring of real-time accumulations one could develop many policies to keep accumulations in their sweet-spots so as to enhance mobility. Modifying traffic signal timings would be one way of improving mobility without affecting the number of trips per mode. But we could also enact strategies that would change the number of trips per mode in favor of the more sustainable modes (e.g., shifting trips from cars to buses). We know that pricing strategies (for example for parking or peak hour tolls) can do this. Significant shifts in modal share should be accompanied by shifts in how space is allocated to modes.

LUTS control model

Improve mobility by perimeter control

Since the MFD is independent of demand, the MFD can be used (e.g., with perimeter control strategies) to ensure that a neighborhood’s vehicular accumulation never enters the gridlock regime; and that it is in fact maintained as closely as possible to its sweet-spot value. This simple strategy (a refined version of those used in London and other cities) turns out to maximize the number of cars and buses that complete their trips at any given time. It can improve everyone’s accessibility. The animation below (taken from Geroliminis and Daganzo, 2007) shows how, by using the traffic signals in the periphery of the SFBD to prevent too many vehicles from crowding the SFBD beyond its sweet-spot, total output is increased. The pane on left side (and the top graph) display the original simulation; and the pane on right side (bottom graph) the one with control. Note how the right side “keeps on ticking” when the left side has collapsed and how it serves many more trips.


Geroliminis N., Daganzo C.F., (2007), Macroscopic modeling of traffic in cities, 86th Annual Meeting Transportation Research Board, Washington D.C.

Geroliminis N. and Levinson D., (2009), Cordon pricing consistent with the physics of overcrowding, Transportation and Traffic Theory, Hong Kong, Springer, 219-240