AUSTIN — The Texas Legislature ended its third special session Monday night after passing a bill and a proposed constitutional amendment that would boost spending for roads and bridge.Lawmakers in both chambers moved quickly to approve the only item on the agenda of the third special legislative session, which Gov. Rick Perry called last week. A deal reached in the House could provide $1.2 billion a year for transportation by diverting half of the money currently flowing into the state’s rainy-day fund. Because the reserve fund was created with a constitutional amendment, voters would have to give final approval in the November 2014 general election. The package’s author, Rep. Joe Pickett, D-El Paso, announced before the debate began that he had met with numerous lawmakers to work out a compromise that could earn a two-thirds majority in both chambers of the Legislature. Previous efforts had failed because conservatives demanded constitutional safeguards for the rainy-day fund, while other lawmakers wanted to retain control over it. Pickett crafted a proposed constitutional amendment that only authorizes the diversion of the funds, while a separate bill provides the mechanism and specifics for when the money is diverted and how it’s spent.The bill creates a joint committee of lawmakers who would decide a minimum balance for the fund every two years, and the diversion of money to transportation projects would stop if the fund falls below that level. Within the first 45 days of every legislative session, lawmakers could vote to change the minimum balance or leave it alone. The bill also requires the Texas Department of Transportation to find $100 million in savings and spend that money to pay off long-term debt. Pickett said that will save an additional $47 million in interest payments. The department would also have to spend the money on projects across the state. Lawmakers of all stripes tried to amend Pickett’s bill, but he only supported those that he knew Senate negotiators would accept. One of the amendments he accepted was to allow the department to spend money on expanding the Port of Houston to accommodate larger container ships after the enlargement of the Panama Canal. The Senate only objected to one amendment, brought by Rep. George Lavender, R-Texarkana, that committed unexpected future revenue to roads. Senate Finance Chairman Tommy Williams, R-The Woodlands, rejected that measure and removed it before sending it back to the House for final passage. Experts say Texas needs to spend $4 billion more per year just to maintain the current road network, but the Republican majority has refused to raise taxes or fees to pay for the work. Diverting money from the state’s savings account was considered the more politically acceptable option. Business groups warned earlier Monday that the Texas economy would suffer if the Legislature didn’t do something to improve the state’s deteriorating infrastructure. Bill Hammond, president of the Texas Association of Business, said the “no new taxes or fees” position of many conservative Republicans was hindering economic development.