The second round of carpocalypse has been postponed indefinitely.

The Oregon Department of Transportation announced Thursday night it's delaying the planned closure of the Interstate 105 onramp from Sixth Avenue that had been scheduled to begin Monday. No new closure date was announced.

The closure was to be the first of four six-week closures so crews can modernize the aging on- and off-ramps that connect motorists on Sixth and Seventh avenues to the interstate.

"ODOT will close all four Sixth and Seventh Avenue on- and off-ramps at some point in the future and we will announce that well in advance," the agency said in a traffic alert.

ODOT concluded the construction work might not be completed in six weeks during its final review of the construction schedule provided by the project's contractor, Eugene-based Wildish Standard Paving Company. The agency calculated the construction could take up to nine weeks based on the contractor's schedule, said Angela Beers Seydel, an ODOT spokeswoman.

ODOT and the contractor are discussing options to bring the closure closer to the announced six-week timeline but haven't reached an agreement, she said.

"In order to ensure the least amount of travel disruption to the community, ODOT decided to postpone the ramp closure until a schedule can be agreed upon," the alert said.

Beers Seydel said ODOT is committed to moving forward with the project and associated closures.

"We're partners in this project," she said, "and the ultimate goal is to come up with a solution that works for everybody."

A Wildish representative couldn't be reached Thursday night.

The two-year, $18 million project will bring the bridges and ramps on I-105 between Delta Highway and downtown Eugene, built in the late 1960s and early '70s, up to current standards.

ODOT said work that doesn't require the road to be fully closed and can be done with lane closures, such as guardrail replacements, will continue as planned. The agency cautioned motorists to anticipate lane closures and shifts in traffic patterns in the construction zone.

The delay is another hiccup in a construction project that got off to a rough start in late October.

ODOT faced criticism from local residents and U.S. Rep. Peter DeFazio, D-Springfield, due to backups on I-105 and noticeable increases in traffic congestion along Sixth and Seventh avenues, and the Coburg Road corridor between downtown and Harlow Road.

ODOT officials acknowledged they could have increased their public outreach about the project's impacts ahead of time, but also noted it's difficult to avoid traffic tie-ups when lanes are closed on a stretch of interstate that typically carries 60,000 vehicles a day.

Once the ramp upgrades are complete this fall, crews will shift to the last phase of the two-year project to upgrade the Willamette River bridge, which will mean more slowdowns for area motorists.

Follow Christian Hill on Twitter @RGchill. Email christian.hill@registerguard.com.