Even as friends and foes of the mayor's congestion-pricing plan debate the now possibly dead initiative, other traffic-killing ideas continue to blossom.Each plan seeks to improve the environment by reducing traffic flow into Manhattan. The question now is whether they will be seriously considered. The alternatives to congestion pricing come from all directions and some ideas are supplements to the mayor's original plan.Congestion pricing "was only one tool of several to reduce the congestion on city streets to clean the air and maintain our economic prospects," City Council transportation Chairman John Liu (D-Flushing) said yesterday.The mayor always contended that expanding bus service and other mass transit improvements were necessary, with or without federal funding, a spokesman said yesterday. In the congestion pricing plan, about 367 additional buses could have headed to the streets to pick up commuters who chose to stop driving to avoid the $8 fee.Liu noted that the mayor offered $200 million from the city to supplement congestion pricing proceeds going toward mass transit, but a mayoral spokesman said yesterday it was too soon to tell if those funds would still roll out.Talk of possible parking permits in residential neighborhoods that could keep commuting motorists out also emerged from the mayor's plan. Cracking down on people using government employee parking placards or civil servants using counterfeits also was a supplement to the plan, a mayoral spokesman said yesterday.Other elected officials, and opponents to Bloomberg's idea, trotted out alternatives from other cities. Assemb. Richard Brodsky (D-Westchester) proposed congestion rationing, aka allowing only cars with specific license plates into Manhattan on certain days.Assemb. Rory Lancman (D-Fresh Meadows) offered an alternative that would provide incentives to businesses if employees carpooled or used mass transit.Transportation advocacy groups maintain that the plan that bore congestion pricing, which they declared still alive, includes other programs that could help ease congestion. Transportation Alternatives spokesman Noah Budnick said the mayor's idea to require commercial buildings to install bicycle parking for employees would help."The lack of secure indoor bike parking is the No. 1 reason why people who want to bike to work don't ride," Budnick said.