A preliminary report by the Federal Railroad Administration says Union Pacific’s failure to maintain its track and track equipment resulted in the oil train derailment in Mosier on June 3.  The report released today says the FRA investigation found that multiple lag bolts in the section of Union Pacific track where the derailment occurred were broken and sheared, leading to tie plates loosening from the ties, which allowed for the rails to be pushed outward as trains moved across them.  The report noted the Union Pacific train was equipped with an air brake system, and FRA-conducted simulations after the derailment showed that if the train was equipped with newer electronically controlled pneumatic brakes, it could have led to a less severe incident.  Union Pacific said Wednesday it would resume oil train traffic through the Gorge this week, with the railroad saying it has an obligation to its customers and under federal law to transport various goods on a daily basis, including hazardous materials.  The FRA says it is evaluating potential enforcement actions, and confirmed a temporary speed restrictions through Union Pacific’s Portland subdivision, including a ten mile per hour speed limit in Mosier.  After release of the report today Senators Ron Wyden and Jeff Merkley, along with the groups Friends of the Columbia Gorge and Columbia Riverkeeper, renewed calls for a halt to crude oil traffic through the Gorge.