Walmart Inc.’s initiatives to strengthen its in-house trucking operations have elevated it to No. 1 on this year’s updated Transport Topics Top 100 Private Carriers list.

Although freight market conditions have been favorable to shippers for the past two years, many of the largest private carriers in North America operate larger fleets now than in years past.

Even at a time when for-hire truck capacity is readily available at com­petitive rates, many shippers have continued to invest in their own private fleets.

Global building materials firm CRH Plc has offered to purchase Australian concrete maker Adbri Ltd. in a joint takeover proposal with Barro Group, valuing the target business at $1.4 billion.

The biggest private motor carriers across a variety of industries experienced ups and downs during the past year as they adapted to changing freight market conditions.

Private motor carriers, like all trucking operations, have adjusted to shifting freight market conditions in the past year as truck capacity has loosened and freight rates have softened.

From food service distributors to in-house trucking divisions of retailers, the largest private motor carriers in North America  have remained busy even as the freight market has cooled.