LANSING, Mich. (AP) - Michigan lawmakers are working to advance a Republican roads funding plan to spend at least $500 million annually by the 2018 budget year. The House transportation committee heard testimony Tuesday on bills in the package that would require warranties on road work to avoid short-term fixes and would change various streams of tax revenue. It holds another hearing Thursday. Minority Democratic lawmakers say a plan to double permit fees for overweight and oversized vehicles doesn't go far enough, since fees are low to begin with and those vehicles have the greatest impact on roads. Some lawmakers also question whether state and local governments have the staff and resources to oversee performance-based contracts and warranties. Michigan Transportation Director Kirk Steudle says officials are still working out the details of those plans.