The Golden State Warriors' plan for a new arena in San Francisco's Mission Bay neighborhood moved a step closer to reality Tuesday when a state appeals court upheld the city's plan to manage increased traffic congestion and said the project would not impede access to a nearby hospital or damage the environment. Neighborhood and environmental groups, led by the Mission Bay Alliance, contend San Francisco's plans for more bus and rail service, street construction and traffic signals are inadequate to handle the new crush of spectators in the urban neighborhood, especially when the San Francisco Giants are playing baseball at nearby AT&T Park. [...] the court said San Francisco's environmental study had reasonably concluded that the project would not interfere with access to the UCSF Medical Center or nearby biotech companies and would not change the character of the neighborhood. [...] Pollak said the city's studies showed that passenger fees would cover the costs, and that the arena owners had agreed to help local and regional transit agencies fund unexpected transit costs in the future. Pollak also said opponents had failed to show that construction would cause excessive noise or...