Hearings slated on railway plan to link L.A. and San Pedro.

The railroad is coming, and the environmental predictions have already arrived.

Transit officials' grand plan to link the San Pedro-area ports to downtown Los Angeles rail yards -- by building a 20-mile-long, non-stop, rail-and-truck thoroughfare -- has been on their drawing boards for a decade.

Now, the first assessment of its fallout for thousands of businesses and homes along the proposed north-south path through seven cities has been published in a two-inch-thick document for the public to review. Business owners and others with concerns have been asked to review its predictions and testify on the issues at public hearings in September and October.

A key finding: About 341 businesses, employing 3,525 workers, would have to be relocated from the proposed route, estimated the study.

Some 327 homes with 1,373 inhabitants must also be moved. Those estimates are valid under the simplest construction design studied, which puts the road beds at street elevations.

Intense concerns voiced by business and home owners along the path, which generally follows Alameda Street north from docks of the Port of Los Angeles and the Port of Long Beach, have spurred local city officials to insist that track and road beds of the so-called Alameda Corridor transit way be below grade, or slightly under ground level.

To that end engineering consultant Daniel, Mann, Johnson & Mendenhall of Los Angeles, which prepared the two-year study, was instructed at the outset by regional transit officials to also consider laying the transit way in a 30-foot-deep trench. That would boost the price tag to $1.4 billion from a $1.1 billion estimate for an entirely above-ground project.

The affected businesses lie mostly in the seven cities: Huntington Park, South Gate, Lynwood, Compton, Carson, Los Angeles and Vernon.

The below-grade option, however, would only relocate a dozen homes and 140 businesses, DMJM estimated. That plan also cuts way back on the thundering rattle created by passage of up to 100 trains estimated to traverse the tracks each day by the year 2020.

That trebling of train traffic from today's levels will result from redirecting to the Alameda Corridor trains that currently use other routes through the county, and from the ports' plans to double cargo traffic by 2020.

Laden with import cargo on their way north to the big switching yards east of downtown L.A., and on to points east, train noise would produce either "severe" or "significant" impacts for 1,053 homes by the year 2010. But with the below-earth option, that falls to 104 homes, and to just 38 dwellings if the thoroughfare is also shielded by 15-foot-tall walls. Thousands of trucks would also contribute to the noise.

One highly regarded component of the Alameda Corridor transit plan is its provision for building bridges or underpasses at some 20 big-street intersections. That would end most of today's congestion at those crossings, where vehicles sometimes wait 10 minutes or more for trains to pass. But the noise-dampening measures, like the walls, have their own property-value downside, the study mentioned. They are targets for vandalism and graffiti and also eliminate views, the report noted. Up to nine miles of these sound walls would be needed if the above-ground bed is built, the study said.

The crucial decision on whether to go below ground level will likely be made by December by the Alameda Corridor Transportation Authority, the governing public agency composed of port and transit officials, DMJM has estimated.

The agency was lobbied repeatedly by Vernon officials, who raised so many arguments during planning sessions that the consultants were also asked to consider a third option, to bypass that small city. But that alternative loop, which would run along Long Beach Avenue through the City of Los Angeles, has been opposed by L.A. officials. At issue are property takings through eminent domain and closing access roads to businesses.

The Alameda Corridor plan would amount to a milestone in rail service to the ports, which has been operating at the Port of Los Angeles since the 1870s.

DMJM has estimated if the authority chooses a plan by the end of 1992, construction would begin in late 1995 and end a decade later.