Menlo Park's most highly trafficked Caltrain crossing at Ravenswood Avenue is the city's priority, but the three other crossings  at Oak Grove, Glenwood and Encinal avenues  have also been factored into the current study.

In 2015, the San Mateo County Transportation Authority agreed to reimburse the city up to $750,000 to conduct another grade-separation study. The city hired the consultant group AECOM for $631,300, and the firm held a community meeting May 2 at the Arrillaga Family Recreation Center to gather public comment.

In 1965, Southern Pacific, which operated the railroad before Caltrain, conducted grade-separation studies on the Peninsula, and then followed up with more grade-separation studies in the 1970s. In 1990 Menlo Park conducted a grade-separation study. In 2003 Menlo Park conducted another such study. In 2009, the San Mateo County Transportation Authority looked at grade-separation alternatives in Menlo Park.

For years, the question of "grade separations"  separating a roadway from the rail line it crosses by using a bridge or tunnel  has periodically risen in Menlo Park, spurring a study on the feasibility of such a project. Then, after the study is completed, the topic retreats from the Menlo Park collective agenda, only to resurface several years later.

A total of 24,000 vehicles cross the tracks at Ravenswood Avenue each weekday, according to the consultants, and that number, too, could increase. The other crossings have lower, but not insignificant, traffic: about 10,000 a day at Oak Grove Avenue, 6,000 at Glenwood Avenue and 5,000 at Encinal Avenue, AECOM says.

Caltrain runs 92 trains per weekday through Menlo Park, and that number is expected to increase: up to 114 trains per day are planned when Caltrain is electrified, and up to 128 trains per day when high-speed rail begins service, said the consultants from AECOM.

With El Camino Real, the Caltrain tracks, and crosswalks at Alma Street all within a short distance, it's a complicated stretch of road for drivers to navigate. As traffic and train trips increase, the hazards could too.

A fatality at the Ravenswood Avenue crossing in February 2015 spurred community support for action to make the crossing safer. Median barriers were installed on Ravenswood Avenue between Alma Street and Noel Drive in an attempt to reduce complications near the crossing that can lead to cars being stopped on the tracks.

If the tracks can't be lowered to ground level in the distance between Ravenswood and Oak Grove avenues, it might make sense to keep Caltrain elevated and build additional grade separations at the city's other rail crossings. That would make the project much more expensive and time-consuming. Examples of hybrid underpasses where tracks are elevated and the road lowered are the crossings at Holly Street in San Carlos, 42nd Avenue in San Mateo and Ralston Avenue in Belmont.

At a 1 percent grade, explained Angela Obeso, Menlo Park associate engineer, it would likely take a long distance to raise the rail line enough to get a sufficient gap between the tracks and the road beneath.

Consultants said that one logistical challenge is Caltrain's non-negotiable requirement that the elevation change of the tracks be at no more than a 1 percent grade. That could complicate things if the city were to go for the hybrid approach of partially lowering the road and partially raising the tracks.

The 2003 study winnowed six options for the Ravenswood Avenue grade separation to two: either tunnel the roadway under the tracks or partially raise the tracks and partially lower the roadway.

Future community meetings on the Ravenswood Avenue grade separation are tentatively scheduled for sometime in the August-September and November-December periods. Future City Council study sessions are planned for October and January.

The construction would most likely require building a "shoofly," a temporary track to reroute the train. A very rough estimate of a construction timeline is 18 to 24 months, but, consultants said, that could vary based on many factors, including which plan the city chooses.

With either option, the project would be a long-term commitment. After the current study is completed on the Ravenswood Avenue grade separation  which is expected to take a year  the project would have to undergo a detailed design process and an environmental impact review, which would likely take several more years, Ms. Obeso said.

One potential problem with the option to tunnel Ravenswood beneath the current track grade is that it could block access to Alma Street from Ravenswood, since there would be only a short distance to bring the road back to the level of the current street. Some residents expressed concern at the community meeting that doing so could shift traffic to nearby streets or make the Burgess Park and Civic Center area difficult to access.

Menlo Park: Another decade, another grade-separation study