LAS VEGAS — In response to $411 million in proposed budget cuts, Clark County School District (CCSD) is changing the start time for 139 schools, beginning in August with the 2011-12 school year.

The changes have been in the planning process for two years. District officials said they will result in increased efficiency in school bus routes and a savings of $10 million, or the equivalent of 143 teaching positions. There will be no impact to the amount of instructional time or the quality of education offered by the district.

“These are very difficult times and everyone must work together and share in the sacrifice as we try to save money,” said Dr. Lauren Kohut-Rost, deputy superintendent of instruction. “Students’ families will have their routines change a bit, and this can be a challenge with siblings of various ages, so we want to give parents plenty of time to start thinking about how they will accommodate the needs of their family.”

Of the 139 schools with changing bell times, 70 schools will see a change of more than 30 minutes. The adjustment comes in response to current bell times and bus routes that have evolved as the district added schools to meet its rapidly rising student enrollment.

As part of the restructuring of school start times, extracurricular activities and programs such as extended school days, as well as magnet and career and technical academy transportation, can continue without further cuts. Officials said that changing bell times will not have adverse effects on the safety or quality of transportation offered by CCSD, and it will not have an impact on the two-mile walking radius in order to qualify for school bus transportation. Additionally, buses will not mix students from different school levels.

Also as part of the school bell time change, approximately 200 buses and routes will be cut from the current fleet of 1,500. The change represents a 200-driver reduction out of the approximate 1,350 drivers employed by the district, with approximately 75 positions currently vacant. CCSD hopes to address most of the cuts through attrition and vacant positions. Maintaining the 200 routes, combined with rising fuel prices, would have resulted in greater costs, officials said.

Finally, by having bus drivers complete more routes during their shift, all drivers will be fully utilized and scheduled in an efficient way. The change will also help reduce the district’s annual bus replacement cost.

A complete list of 2011-12 school bell times is available at www.ccsd.net.