President Bush issued an executive order yesterday directing federal agencies to speed environmental reviews of important transportation projects, arguing that highways, airports, and other such projects are critical to the nation’s economy and need to be freed of red tape. Environmentalists immediately denounced the move, calling it part of a systemic effort to restrict public debate and undermine environmental protections, including the 32-year-old National Environmental Policy Act. That act requires federal agencies to study and disclose the environmental impact of their actions and to involve the public in their decision-making processes. Secretary of Transportation Norman Mineta claims the permit system has increased the time it takes to build an airport to an average of 10 years and a new highway to an average of 13 years, but Fred Krupp, executive director of Environmental Defense, disputed claims that any projects had been significantly delayed by environmental impact studies.