The Equilibrium assignment Bi-conjugate Frank Wolfe (BFW) is a further development of the method Frank Wolfe (FW). In Visum, the Equilibrium_Lohse assignment becomes a variant of FW if impedances are not smoothed. In this case, the volume is moved towards shortest paths with a fixed step size. The assignment procedure BFW was implemented based on the publication of Mitradjieva, Lindberg et al (2013). Compared to the Equilibrium_Lohse assignment, convergence is enhanced through the relative gap with the same number of iterations, typically by approx. one to two orders of magnitude, i.e. instead of 1e-003, values of 1e-004 or 1e-005 are obtained. The procedure, as well as the Equilibrium_Lohse assignment, were parallelized and scaled based on the number of cores used, so that runtimes could be significantly reduced through the use of better hardware.
