Will Power went quickest for Penske in the second IndyCar practice session in Baltimore.
Delays once again hampered running while the series worked on mitigating the bumps that were causing cars to launch earlier in the day.
Despite earlier hopes that the bumps could be removed by regrinding the affected area of the track, IndyCar elected to install a temporary tyre barrier, with a permanent chicane set to be built overnight. The changes give the circuit a new official length of 2.03 miles.
Power christened the revised layout with a best time of 1m21.4572s, which for much of the session was around 0.4 seconds quicker than anyone else could manage before Schmidt-Hamilton's Simon Pagenaud managed to post a lap within 0.0311s of the Australian's in the last couple of minutes.
Scott Dixon was third-fastest ahead of early session leader Rubens Barrichello.
The half-hour session was interrupted by just one stoppage, with title contender Ryan Hunter-Reay bringing out the red flags after encountering problems early on. He was able to continue running once the session restarted.
Pos Driver Team/Car Time Gap 1. Will Power Penske Dallara-Chevy 1m21.0185s 2. Simon Pagenaud Schmidt Dallara-Honda 1m21.4883s + 0.4698s 3. Scott Dixon Ganassi Dallara-Honda 1m21.7211s + 0.7026s 4. Rubens Barrichello KV Dallara-Chevy 1m21.9194s + 0.9009s 5. James Hinchcliffe Andretti Dallara-Chevy 1m21.9236s + 0.9051s 6. Sebastien Bourdais Dragon Dallara-Chevy 1m21.9288s + 0.9103s 7. Ryan Hunter-Reay Andretti Dallara-Chevy 1m22.0263s + 1.0078s 8. Mike Conway Foyt Dallara-Honda 1m22.1075s + 1.0890s 9. Dario Franchitti Ganassi Dallara-Honda 1m22.1254s + 1.1069s 10. Charlie Kimball Ganassi Dallara-Honda 1m22.3243s + 1.3058s 11. EJ Viso KV Dallara-Chevy 1m22.3276s + 1.3091s 12. Helio Castroneves Penske Dallara-Chevy 1m22.3529s + 1.3344s 13. Tony Kanaan KV Dallara-Chevy 1m22.4897s + 1.4712s 14. Ryan Briscoe Penske Dallara-Chevy 1m22.5584s + 1.5399s 15. JR Hildebrand Panther Dallara-Chevy 1m22.6031s + 1.5846s 16. Graham Rahal Ganassi Dallara-Honda 1m22.6543s + 1.6358s 17. Justin Wilson Foyt Dallara-Honda 1m22.8225s + 1.8040s 18. Marco Andretti Andretti Dallara-Chevy 1m22.9129s + 1.8944s 19. James Jakes Foyt Dallara-Honda 1m22.9542s + 1.9357s 20. Takuma Sato Rahal Dallara-Honda 1m23.1126s + 2.0941s 21. Simona de Silvestro HVM Dallara-Lotus 1m23.1360s + 2.1175s 22. Alex Tagliani Herta Dallara-Honda 1m23.1635s + 2.1450s 23. Bruno Junqueira Fisher Dallara-Honda 1m23.6249s + 2.6064s 24. Ed Carpenter Carpenter Dallara-Chevy 1m23.8550s + 2.8365s 25. Oriol Servia Panther/DRR Dallara-Chevy 1m24.6311s + 3.6126s