The court rejects petitions seeking a return to the ballot system or to tally all paper slips generated as proof of voting for votes recorded by electronic machines
Attacks in the Punjab provincial capital have become less frequent over the past couple of years but Islamist militant groups are still active there and periodically carry out major attacks.
"It was a bomb blast in a fruit truck that wounded 22 persons," provincial Punjabi government spokesman Malik Muhammad Ahmad Khan said.
Haider Ashraf, deputy inspector general of police, said the truck was loaded with explosives and experts were combing through the wreckage.
"Allah has saved Lahore from big destruction," Ashraf told local ARY television channel.
Last month a suicide bomber from the militant group Pakistani Taliban killed at least 25 people in Lahore, many of them police.