I've been playing SC4 for awhile now, but have just begun to successfully build a large city without losing money. I have a population of 50,000 on a large city layout. It is divided into quarters - 1/4th Industrial, 1/4 Commercial, and 1/4 Residentials in opposite corners. I'm noticing homes are not being built in the outer spaces of my Residential zones, even though the demand is high. Is it possible that I need to introduce mass-transit to the Commercial area in order to promote more Residential building? My traffic congestion is green. Also, what form would be suggested for a virgin mass-trasiter like myself? Does the 8-to-10 tiles rule apply to all forms of mass transit?