The $3 million ER expansion tha topened Wednesday at St. Christopher’s Hospital for Children was a response to increasing demand, said Christopher Haines, director of the department of emergency medicine. “It gets us to where we can provide care much more quickly,” Haines said of the expanded space. ER visits to the North Philadelphia hospital increased from about 50,000 six years ago to about 70,000 last year, Haines said. He said he did not know why demand was increasing. About one-third of patients are directed to the hospital’s urgent-care center, which treats problems that often could have been handled in a primary-care doctor’s office. Most patients have insurance. The hospital added 14 private exam rooms and 4,300 square feet. The department now has a total of 17,300 square feet, 36 exam rooms, and a trauma bay. The new emergency room has two rooms earmarked for treating children who are victims of child abuse or sexual assault or who need psychiatric evaluation. Haines said he would be hiring more doctors.