NORTH LITTLE ROCK — Work on demolishing the Broadway Bridge on the Arkansas River between Little Rock and North Little Rock reached a new milestone Saturday morning as a crew detonated explosive charges that brought down two of the remaining three concrete arches.

The third remaining arch of the 93-year-old structure was to be taken down by a work crew later. Although it was supposed to come down in the explosion, it stayed upright, requiring a crew to remove it manually. Danny Straessle, a spokesman for the Arkansas Highway and Transportation Department, confirmed that all of the explosives detonated and the arch was heavily damaged.

“I’ve gotten word that no live explosives are remaining in the structure, that the explosives in the third arch did ignite, so there’s no danger of an unexpected explosion. A crew confirmed that it blew the bottom out of the arch and they’ll knock the rest of it down today,” he said, adding that the debris from the arches will be removed over the next few days.

Because the north side of the river is not used by barge traffic, Straessle said the debris and removal activity would have no effect on river traffic. The navigation channel was closed Saturday only for the demolition and subsequent inspection, he said.

“The riverbed is not as deep on this side of the river, so debris removal should be relatively easy,” Straessle said. “When they demolished the deck, pieces were falling into the water and they pulled them out later. There’s no time requirement for them to get this out of the river, but all the rebar has to be removed and any concrete debris larger than a bowling ball has to come out.”

The demolition is being carried out by Explosive Services of Helotes, Texas, under a contract valued at nearly $314,000. A third demolition is scheduled to take place sometime next week, to remove the vertical columns that supported the old bridge. Massman Construction of Kansas City, Mo., is responsible for removal of the debris.

AHTD received reports that the concussion was heard and felt as far away as the Little Rock neighborhood of Hillcrest, about three miles from the detonation site.

Massman, which was awarded a $98.4 million contract by AHTD, is required to have the new bridge in place and ready for traffic by March 30 or face a penalty of $80,000 for each day the project goes past the deadline for completion. If the bridge is ready before the deadline, the company will receive a bonus of the same amount for each day ahead of deadline the job is finished.

The bonus is capped at a maximum of 50 days, or $4 million, Straessle said. There is no cap to the penalty for not meeting the deadline, he said.