Once completed, Caltrain's effort to electrify its rail system will allow the agency to run more -- and cleaner -- trains up and down the Peninsula.

But in the meantime, Palo Alto residents should brace for months of nighttime construction, disruptions in weekend service and the removal of dozens of trees near the railroad corridor.

The project has been in the works for about a year, though so far it has taken place mostly in the northern part of the Peninsula, between South San Francisco and Menlo Park, and in the southern part, between Santa Clara and San Jose. Now, Caltrain is kicking off work in the remaining two segments: San Francisco and north Santa Clara County.

On Tuesday, Caltrain officials hosted a community meeting in Palo Alto to update residents about the benefits and impacts of the electrification project, which aims to improve train performance, increase ridership capacity (and, hence, revenues) and replace the existing diesel fleet with cleaner and quieter trains powered by electricity.

But for many of the roughly 60 residents who attended the meeting at Lucie Stern Community Center, the biggest concerns pertained not to the immediate disruptions but the long-term one: the need to reconfigure the tracks at Palo Alto's four rail crossings to accommodate the expected increase in train service. The city is set to pick its preferred "grade separation" design for the four rail crossings by the end of this year, or early next year.

The $1.98-billion electrification project involves the installation of an overhead contact system (OCS) along the entire length of the 51-mile corridor, a system that will be supported by poles that will be placed roughly 180 feet apart, according to Greg Parks, Caltrain public-involvement manager. Caltrain plans to install about 3,000 poles along the corridor, including 196 in Palo Alto.

The poles and the wires won't be installed until the summer and fall of 2019, at which time Caltrain will also be installing a paralleling station (equipment that ensures that the correct level of voltage is distributed through the OCS) on its land just south of Page Mill Road. This summer, Caltrain will be testing soil conditions and potholing for utilities, a process that Parks said is the noisiest task on the agency's worklist (at 70 to 80 decibels, the acoustic levels are "between a garbage disposal and a vacuum cleaner," he said).

Some of the work will be done at night, between 7 p.m. and 7 a.m., which Parks said is necessary to avoid disruptions to service.

Even with these measures, residents who like to catch the train to San Francisco on the weekend, should brace for some impacts starting this fall. Between Oct. 6 and March 17, Caltrain will suspend its weekend service between the Bayshore station in Brisbane and the two San Francisco stations at Fourth and 22nd streets. Bus shuttles will be provided during that time.

Caltrain also will be removing and pruning trees this fall, Parks said. The agency plans to remove 52 trees in Palo Alto on Caltrain's right-of-way, as well as an additional five on public property (no trees will be removed on private property). The agency plans to significantly prune 63 trees in Palo Alto (53 on Caltrain's land and 10 on other public property), and lightly prune (by less than 25 percent) another 357 trees.

To offset these impacts, Caltrain plans to plant 120 trees, Parks said. He also said the agency will try to minimize the impacts of construction by installing acoustic-barrier blankets and by positioning lights away from homes to avoid disturbing residents.

One disruption that could occur during the construction period is the closure -- full or partial -- of grade crossings, Parks said. The agency has no plans, however, to close any lanes on Alma Street, the busy artery that runs parallel to the tracks.

Residents had plenty of questions for Caltrain about the upcoming work. Several asked about tree removals and, in particular, the project's impact on El Palo Alto, the city's namesake redwood. Casey Fromson, legislative director for Caltrain, said the agency defers to cities to make determinations on which trees require extra protection. She also assured the audience that Caltrain is being "extra sensitive" about any potential pruning needed to El Palo Alto.

"We're working with the city, and maybe it's the city that needs to do the pruning, if it's needed," Fromson said.

While Caltrain officials focused on discussing electrification, the elephant in the room was grade separation -- a project that is now being evaluated by various cities all along the corridor, including Menlo Park, Palo Alto, Mountain View and Sunnyvale. Many wanted to know whether Caltrain's work on electrifying its fleet will preclude Palo Alto from pursuing grade-separation alternatives that include lowering the trains over surface roads, or vice versa.

Fromson assured them that it does not and that Caltrain could potentially modify the electric system to accommodate the new road and track alignments once they are constructed.

"When you think about it, it's not that big of a deal to move the poles and wires," Fromson said.

Not everyone was entirely satisfied with the focus of the meeting. Parag Patkar, who lives near the Charleston grade crossing, said that grade separation is "a far greater concern than the electrification of tracks."

"I'm not sure that Caltrain understands that fact," Patkar said. "I'm less concerned about the electrification of the tracks than the impact and consequences of it, which is grade separation."

When he asked who else feels that way, most of those in the room raised their hands.

Fromson said Caltrain would be happy to discuss grade separation at a future meeting. She noted that Caltrain has 42 at-grade crossings along its corridor that can potentially be separated.

"There are many cities that are thinking about this issue and working on what alternative makes the most sense for their city and what works for Caltrain," Fromson said. "It takes years to do that, just like it took 20 years to do the electrification project."