Metamodel-Based Optimization Method for Traffic Network Signal Design under Stochastic Demand

Table 3

Computation time and optimal solution with initial points (0.3, 0.7, 0.73, and 0.27).

Method	Computation time (s)	Improvement factor (iteration)	Total travel cost (veh/h)	Increase in total travel cost (%)
The original problem under stochastic demand	10.236		2008.76
Physical metamodel	0.8067	12.69 (5)	2052.96	2.20
Combined metamodel method with model bias	0.7598	13.47 (5)	2013.22	0.22
Gradient-based metamodel	1.8562	5.51 (10)	2010.59	0.09