Posted on Misc.transport.roads Thought this might be an intresting scene to model. The railroad could disapear into the backdrop or into staging after going under the bridge.
On westcoastroads.com I found a pic of CA 99 showing that the south bound lanes cross over the tracks, while the northbound lanes pass under the tracks through a viaduct.
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It appears the northbound lanes under the viaduct were the original US99 while the lanes passing over the tracks were added later. I guess Caltrans wanted to save some money by keeping the original US 99 ROW when they upgraded this section. IIRC, there's a similar railroad overpass/underpass arrrangement somewhere on 4 lane US 36 in northwestern Missouri. I'm not sure such an arrangment would stand up to scrutany if it's going to be upgraded to I-quality standards? It depends if the viaduct has height/clearance issues.