Shares in Jacobs Engineering Group Inc. ballooned more than 8 percent after the company announced strong first-quarter earnings that beat ambitious Wall Street expectations.

Jacobs reported first quarter net income of $61.3 million ($1.01 per share), a 43 percent increase over $43 million (72 cents) for the same period a year earlier. That exceeded analysts’ expectations of 89 cents per share, according to Thompson Financial.

Revenue for the Pasadena-based engineering and consulting firm also climbed 20 percent to $2.02 billion. The company credited a strong backlog of business from infrastructure projects in the U.S. and abroad for the surprising jump in earnings, increasing its 2007 forecast to $4 to $4.30 per share in net income from $3.75 to $4.05 per share.

“Our first-quarter results are good, giving us a strong start for fiscal 2007. We expect fiscal 2007 to be a year of significant earnings growth for the company,” said President and Chief Executive Craig Martin.

Shares in Jacob’s were up $6.60 to $87.06 in midday trading Tuesday.