Trucker Yellow Corp. is pushing ahead with a sweeping overhaul aimed at making the large but financially problematic carrier more competitive in a resurgent freight market.One of the largest trucking companies in the US., Yellow will combine its regional and national trucking operations into one merged network, a move the company reckons will develop operations, get rid of waste, and make it simpler for clients such as Walmart Inc. to book shipments.Overland Park, Kan,-based Yellow had been battling for years when the pandemic sank the company into a liquidity crisis. A $700 million federal coronavirus-relief loan provided a lifeline that allowed debt-laden Yellow, then called YRC Worldwide Inc., to invest in new equipment and pay off millions in missed health, pension, and other obligations. Despite the federal support, which the government stated that it provided because the company is the main supplier of military transport services, Yellow has lagged behind its peers as the rebounding American economy has encouraged more demand in freight.