Large road and highway builders in northern Nevada worry that the pipeline of civil projects is finally drying up due to budget shortfalls with county and government agencies.RTC-5, the regional gas tax that was passed in 2009, funded much highway and infrastructure work, says Craig Holt, vice president and co-owner of Sierra Nevada Construction. But SNC and other companies are getting worried that the funding may dry up for projects let by the Regional Transportation Commission and Nevada Department of Transportation."It really is a problem with civil work," Holt says. "RTC-5 funded a bunch or work, but that is basically …