Many readers have complained about the horrible traffic at the Old Redwood Highway overpass at the Highway 101 interchange. Caltrans crews are building a new interchange, including a wider bridge and new on- and off-ramps. They are building the project in the footprint of the current bridge and have to build it in stages to keep traffic moving.

Recently, Caltrans shifted traffic to work on the loop on-ramps. The current configuration and temporary traffic lights have caused significant delays for motorists. This configuration will last into November, when the loop on-ramps are finished. The entire project is expected to wrap up next summer, meaning more delays and traffic. Drivers are advised to use other interchanges to access the freeway during the construction.

E. A. Barrera at our partner, the Petaluma Argus Courier, spoke with Caltrans spokesman Allyn Amsk about the project. Read the full story here. Some excerpts:

Caltrans spokesman Allyn Amsk said the original intersection of Old Redwood Highway and Highway 101 was constructed in 1955, and needed significant improvements to meet current and projected traffic conditions. The new interchange will come with new on-and-off ramps, each with two lanes. The highway will be widened to accommodate standard shoulders. And sound walls will be built next to existing sound walls along the southbound highway. Amsk noted that the original bridge was built with “non-standard vertical clearance” – meaning large trucks built in the ensuing years and traveling on Highway 101 sometimes got struck on the bridge.

“Caltrans is building a new bridge in the footprint of the old bridge, widening the bridge, raising the height, and at the same time trying to keep ramps open,” said Amsk.

Amsk said construction stages for completion of the project made traveling through the intersection difficult and suggested that drivers change their habits during the project’s construction.

“In order to keep the interchange open, designers staged construction to alternately close the loop and diagonal on-ramps. ÓThis method allows all movements at the intersection to remain open, but requires frequent changes to traffic conditions and temporarily reduces the capacity of the intersection,” said Amsk.

Amsk said Caltrans was preparing to alter construction of the project to speed things up, including the possibility of adding a second construction crew and allowing crews to work extended hours and days.

“With this strategy we expect the loop on-ramps to re-open by the end of October or early November,” said Amsk.

But Amsk warned that these new measures would only provide “temporary relief during the next stage of construction.”

“Future stages will require new closures, and full traffic relief is not anticipated until project completion,” said Amsk. “For motorists who must use the interchange, we recommend leaving earlier and allowing more time to reach their destination. If possible, motorists should consider using an alternate route.”

Amsk said Caltrans advised that for Highway 101, motorists should consider using the on-and-off ramps at East Washington Street.

“To access southbound US 101, there is also an on-ramp at Pepper Road. To get to the Pepper Road on-ramp, travel north on Stony Point Road from Old Redwood Highway (Petaluma Boulevard North). To cross Highway 101, motorists should consider using Corona Road or East Washington Street.,” said Amsk

Amsk said the project is ahead of schedule and anticipated to be competed in the summer of 2015.

“This will come to an end,” said Amsk.