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How might the Chileno Valley Road crossing solution work?
Cheryl Brehme, Phillip Gould of USGS and Charles Tornaci of Dokken Engineering presented 8 different scenarios for built road crossings to the CVNB recently.
The full 8 scenarios can be viewed here, but the fullest-featured/most comprehensive (and, of course, most expensive) version can be seen in the figure above ("Scenario 1").
In this "Cadillac" scenario, because the newts cross everywhere along the one-mile crossing area between Laguna Lake and the hillside above Chileno Valley Road, the crossings are placed every 15 meters along the whole road. Cheryl explained that crossings, probably culverts or underpasses, must have certain features for the newts to use them. These include light coming in from above, a smooth floor even with the crossing entrance and exit, a sufficiently wide passage, and other characteristics. Traffic safety, the weight of agricultural trucks, overhead power lines and land ownership are all limiting factors.
The figure below provides an example of the type of under-road construction being considered for Chileno Valley Road. The figure shows a cross-section of an under-road passage, featuring an elevated road to allow newts to enter the culvert at ground level, a grated lid to let light into the culvert from above, a level bottom designed to appeal to the newts, and an ample 30-inch minimum width.
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