Lawmakers and advocates urged Mayor Michael Bloomberg yesterday to replace outgoing Transportation Commissioner Iris Weinshall with a visionary transportation planner who will make bold moves to ease traffic congestion and cut pollution."The choice of transportation commissioner is a hugely important statement about the mayor's transportation policy," said City Councilman David Yassky (D-Brooklyn).The pick will be Bloomberg's first significant move in carrying out the 2030 sustainability plan he announced in December, Yassky added.Ms. Weinshall, who soothed the frustrations of Island officials when she and Bloomberg formed the Traffic and Transportation Task Force here nearly a year ago, will be leaving in April to join the City University of New York as a vice chancellor.Her successor must, above all, expand on the task force's work, said Councilmen Michael McMahon (D-North Shore) and James Oddo (R-Mid-Island/Brooklyn). "We don't need a caretaker," said McMahon. "We need someone who will bring a vision and the energy to help Staten Island bring its transportation and mass transit network out of the 19th century and into the 21st century." Added Oddo, "Through the creation of the task force, the current administration indicated that they recognize the seriousness of the situation on our roads. The next commissioner should share this view."According to a statement released yesterday by City Hall, "The Mayor will appoint a commissioner who will carry out policies to meet the sustainability challenges he outlined in his '2030' speech and will continue Commissioner Weinshall's work reducing pedestrian fatalities and increasing safety for all New Yorkers through the implementation of innovative programs like Thru Streets."Bloomberg, who with Health Commissioner Thomas Frieden pushed through the unprecedented bans on smoking and trans fats, should take that same intrepid approach with the next transportation commissioner, said Gene Russianoff, attorney with the Straphangers Campaign. "If you look at a dynamic leader like Thomas Frieden ... you can see what a transportation commissioner can accomplish," said Russianoff.Transportation advocates said the next commissioner must relieve New Yorkers' dependence on cars, said advocates. In the rest of the city, that largely means improving conditions for walkers, cyclists and subway riders.But here, in the city's most car-dependent borough, the most important development is the Bus Rapid Transit service, or BRT, said Russianoff. BRT gives express buses a dedicated curbside lane in which cars are banned during certain hours. City officials hope that the swift ride will convince commuters to leave their cars at home. "The pokiest buses often are on Staten Island because they have really huge distances to go and service is inadequate to begin with on Staten Island," said Russianoff.But BRT won't arrive on Hylan Boulevard until next year, at which point officials will examine whether to expand it to other routes.Advocates say commuters can't wait that long."Pretty much all of Staten Island routes could use a lot of improvement," said Paul Steely White, executive director of Transportation Alternatives. "Travel times are very unreliable."A leading candidate for the post is Joan McDonald, senior vice president of transportation for the city's Economic Development Corp., according to an article on Friday in Crain's Insider.Councilman John Liu, who chairs the Transportation Committee, said Ms. McDonald would be a good choice. "Transportation policy is the underpinning to a lot of economic development issues," he said. "It would probably be valuable to have someone come into that position from somewhere outside the DOT."