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Geometric Design

Alternative II: Minimum Environmental Impact

Alternative II is a high-speed rail alignment designed with two goals in mind: to minimize the impact to the Angeles National Forest and to increase constructability by breaking up the tunnels into shorter, more manageable segments through the San Gabriel Mountains.  This alignment avoids the interior of the Angeles National Forest.  Alternative II begins at the underground station in Burbank and heads northwest towards Santa Clarita along the existing Metrolink corridor.  Before reaching Santa Clarita, the alignment curves to the northeast and tunnels underneath the mountains for a short stretch, then follows Soledad Canyon Road east to the community of Acton.  The alignment then curves north towards Palmdale into the longest tunnel segment.  It then continues to the Palmdale HSR Station.  Below, is a figure that displays Alternative II's alignment and shows tunnel, at-grade, and aerial structure segments.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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The following table displays how much of the alignment is designated as tunnel, at-grade, station, or aerial structure, as well as total length.

While the total length of bored tunnel is 30.08 miles, they are broken up into shorter segments to make the overall tunnel construction faster and more feasible.  Three shorter tunnels can be built faster than one longer tunnel because more crews can be working simultaneously.  The longest bored tunnel segment on this alignment is 15.45 miles.  Rail tunnels over 20 miles are rare in the world.  While it can be done, it proves to be more challenging the longer a tunnel is. Therefore by breaking the tunnels up into shorter segments, the overall constructability is increased.

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