Peripheral arterial disease (PAD), in which arterial blockages prevent normal blood flow from perfusing the area distal of the blockage, can lead to claudication and limb ischemia. Collateral vessels provide an alternate pathway for the blood flow to reach that area. The collateral pathways compensate for the blockage by increasing diameter, number, and length of vessels. It remains unclear if the most significant compensation occurs by new small arteriole growth or an increase in the size of small arteries. A mathematical model of resistors is used to investigate the factors of collateral compensation which have the greatest influence on restoring blood flow.