 Complete the following phrase:  The effects of these changes were higher cornering speeds and higher G-forces on drivers, but not necessarily greater safety. Driver fatalities continued to mount on board tracks into the 1920s, and included four Indianapolis 500 winners, three of which occurred at the Altoona track another Pillsbury design in Tipton, Pennsylvania, and three in the same years in which the driver won at Indianapolis. Winner of the 1919 Indianapolis 500 Howdy Wilcox died in an Altoona race on September 4, 1923, while co-1924 winner Joe Boyer and 1929 winner Ray Keech both suffered fatal accidents at the facility in the same years as their Indianapolis 500 wins  Keechs occurring only seventeen days after, on June 15, 1929. Gaston Chevrolet, winner of the 