The Charleston-Arastradero Road corridor in Palo Alto may not be the city's most famous road but it is undoubtedly its most controversial.

The 2.3-mile segment between Fabian Way and Gunn High School has morphed over the past decade from a four-lane street to a two-lane one in numerous locations, with mixed results. City officials have overwhelmingly supported the changes, which were implemented over two phases on a trial basis and then made permanent in 2008 and 2012, respectively. Bike advocates and school officials have lauded the new bike lanes and traffic-calming measures that the project brought to a busy street serving 11 schools.

But many drivers and neighborhood residents fume and shake their heads when they hear mention of the project they blame for turning their main artery into a congested bottleneck. The project became a lightning rod during the 2013 battle over a proposed housing development on Maybell Avenue, which opponents routinely citing the congestion as evidence that the area is ill-suited for more traffic and density.

Now, 12 years after the City Council first directed staff to address safety on Charleston-Arastradero, officials are preparing to make more changes. On Wednesday night, the Planning and Transportation Commission will review an $8 million proposed project for the corridor, which includes new buffered bike lanes at various sections, raised medians to reduce U-turns, and new right- and left-turn lanes at other sections.

Near Terman Middle School, one of two eastbound lanes would be eliminated and 18 parking spaces removed to accommodate a new right-turn lane. Near Gunn High, recently implemented bike improvements would be further refined and a bike path added on the east side of the street, leading from Gunn to the existing trail toward Los Altos. A new crosswalk would also be installed between Gunn and the new multi-use trail.

At El Camino Real, bike lanes are proposed in each direction across the intersection. A raised crosswalk across the southwest corner would slow the high-speed right-turning traffic. Also, the plan includes an optional bike box at the southwest "pork chop" island to allow bicyclists to make a two-stage left turn from southbound El Camino to eastbound Charleston. Improvements at this intersection are subject to pending review and concurrence by Caltrans, which governs El Camino, the report states.

On the west side of Alma Street, a concrete median is proposed from around Park Boulevard to the train tracks. It would prevent left turns to and from Park Boulevard with the aim of improving traffic flow. A small opening in the new median would allow bicyclists to cross, according to Boyd's report.

Farther east, Wilkie Way would get a left turn onto Charleston in both directions. Near Hoover Elementary School, a landscaped median island will be installed between Carlson Court and Nelson Drive to preclude left turns and U-turns from eastbound Charleston. Even farther to the east, Louis Road would get a widened intersection and an enlarged median refuge for bicyclists.

Furthermore, the prior improvements will take on a more permanent look and feel. While the trial projects used pavement striping and marking, this final phase will "complete hardscape elements" along the corridor, according to a report from Holly Boyd, senior engineer at Public Works. Though none of these changes, in of themselves, are expected to be nearly as controversial as the two-phased reduction of lanes from four to two, collectively they add up to a significant project with a price tag of more than $8 million.

The City Council has already included $7.5 million in funding for Charleston/Arastradero improvements through the infrastructure plan it approved last year. The project has also secured $1.45 million in grants for the permanent build-out of the project, according to Boyd.

In the report, Boyd cited neighborhood concerns about increased traffic congestion along the corridor but argued that the problem goes far beyond this project.

"The general growth in traffic is a regional and citywide issue, which we will have to address as a community no matter what we do in this corridor," Boyd wrote. "This effort needs to include increased Caltrain capacity, citywide bicycle facility improvements, expanded commuter and community shuttle service, trip reduction strategies for new and existing employment and efforts such as the Transportation Management Association."

The new improvements have overwhelming school-community support. Joy Henry Hinton, president of the Gunn High School PTSA, submitted a letter on behalf of the organization endorsing the new concept plan. It's time, Hinton wrote, to "put the hardscape improvements in place that will deliver the lion's share of safety benefits to all users."

"These plans provide planted medians, intersection and signal improvements, bulbouts, multi-use paths, buffered bicycle lanes, a dedicated auto right turn lane into the Terman campus from eastbound Arastradero, and built enhancements at the Gunn HS entrance and Arastradero approaches," Hinton wrote. "The project is a key component of the south Palo Alto bike boulevard network, connecting PAUSD corridor schools to residences and after-school destinations."

Hinton's counterparts at Juana Briones, JLS, Terman and Hoover likewise signaled their support for the proposed amenities. Jong-Mi Lee, president of the Hoover Elementary School PTA, lauded the new dedicated left-turn signal near the Nelson/Charleston intersection, which would "separate the movement of cars and bicyclists through this intersection, keeping bicycle commuters safer."

"The many new safety features for bicyclists and pedestrians as well as the landscaped medians will do much to transform the street from its current expressway-like character to a more residential character that will encourage safer driver behavior," Lee wrote. "More importantly, it will encourage more students to bicycle and walk to 'superblock' schools by providing a safer place for them on this well-used school commute corridor."

Cheryl Lilienstein, president of the group Palo Altans for Sensible Zoning, took a more skeptical stance and urged the council not to approve the changes until it considers their long-term impact on the city. She pointed to the traffic backups currently occurring on the corridor and said it recently took her neighbor 20 minutes to drive 2.2 miles on the corridor from the Page Mill and Arastradero intersection to the Gunn High traffic light. Once there, she parked her car in the Gunn lot and elected to walk the remaining 1.6 miles to get home. In another episode, Lilienstein said it took her son 30 minutes to drive 3.8 miles from the Page Mill exit on Interstate 280 onto Arastradero to get home. This was more time that it took him to drive from San Francisco to the highway exit, she wrote.

"I understand that bike safety has been the primary concern, and that students on bikes, and bike commuters too, need safe routes to schools," Lilienstein wrote. "Yet: Efficient transit for cars is essential for safety and a healthy environment. It's not safe to make drivers insane with frustration and it's not healthy to fill the air with exhaust from traffic jams. We ALL need to get to where we are going in timely and responsible manner."