How Bloomberg Has Left His Mark Re "The Bloomberg Legacy" (column, July 15): Bill Keller discusses many accomplishments of Mayor Michael R. Bloomberg. Yet three specific accomplishments deserve greater emphasis for their role in improving the city, all of which are also manifest in Times Square: reducing crime (beyond already historic lows) by over 30 percent since 2001; enabling explosive growth in tourism (from 43.8 million visitors in 2006 to 52 million visitors in 2012), which almost single-handedly made up for the hemorrhaging of financial services jobs during the same time; and changing the paradigm for how we use and think of roads - as public spaces that can serve pedestrians as well as cars and in so doing serve the environment as well. TIM TOMPKINS President, Times Square Alliance New York, July 15, 2013 Bill Keller says Mayor Michael R. Bloomberg has turned New York City into "a world leader of sustainability." I disagree. New York - like all American cities - badly lags the rest of the industrialized world. It is true that the mayor has promoted several initiatives that point in the right direction, such as bike lanes and bike sharing - both of which have been common in many European cities for decades. But the true problems of sustainability in New York City remain unresolved. The city continues to work on an outdated, wasteful electricity grid. The water treatment capacities are laughable; every time it rains, unfiltered sewage runs into the rivers. Trucks and buses in the city continue to be louder and more polluting than in many places. Recycling is another area where New York has to catch up. But most disconcerting is the disgraceful state of most buildings in New York City. Heating and cooling systems as well as insulation are not worthy of a 21st-century city. It is not unusual for Americans - especially American politicians - to overestimate their credentials on environmentalism. You will never hear from somebody like Mr. Bloomberg about the hundreds of billions of dollars it will cost and the fundamental changes in everyone's daily life it will take to make a city like New York truly sustainable. Bill Keller's focusing on the engineer in Mayor Michael R. Bloomberg (who studied to be one) underscores qualities that we need in public servants. An engineer is not led blindly by rules. An engineer does not substitute consensus for hard facts. And an engineer seeks innovation rather than the temporary fix. Let us break the gridlock in Washington and in our state legislatures by electing fewer politicians and more engineers and other educated, creative architects of society. The writer is professor emeritus of chemical and biological engineering at Iowa State University.