** Railroad’s shares rise 4 pct to $176.40 premarket
** Co tops Q1 profit estimates as pricing gain helped the railroad co offset impact of severe winter weather, flooding that damaged rails in the Midwest
** However, revenue of $5.4 bln misses estimates of $5.50 bln as business volumes, freight revenue decline
** Operating ratio improves 1 point to 63.6 pct from a year ago; a lower ratio means more efficiency and higher profitability
** UNP shares have risen 22.5 pct YTD (Reporting by Rachit Vats)
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