For many parents, back to school means back to work. So finds a new survey by FlexJobs, which reports that as kids hit the books in the fall, working mothers (and dads, too) who have been focused on parenting prepare to shift gears toward their professional life.

The study of more than 1,300 parents found that approximately one-third (33 percent) expressed the intention to boost both their job-search efforts and their productivity level.

Not surprisingly, what these parents want is workplace flexibility. The survey showed that 82 percent of respondents with kids in school would like to have flexible job options.

While more flexibility at work may be appealing to almost anyone with a job, there are several reasons why working parents – and particularly working moms – want this. Commute time savings, work-prep time savings and cost savings top the list.

Less road time. If you find your commute unbearable, you're not alone. FlexJobs found that one in three workers have a daily commute of two or more hours each day. An unlucky 8 percent have had commutes up to four hours long, and 6 percent spend more than four hours schlepping back and forth to work each day. The latter category tallies at least 20 hours a week on the road – the equivalent to taking on another part-time job. For parents with small children at home or school-age kids who need to be picked up, long commutes translate to impractical schedules and missed family opportunities.

Skip the shower. Heading to the office means spending time getting ready to go – morning time that working parents already have in short supply. Nearly three-fourths of women (or 67 percent) take more than a half-hour to primp and prepare before work, with 1 in 10 taking an hour or longer. More than half of men surveyed (54 percent) spend more than 30 minutes on their morning routine as well. Flex workers who work from home can cut or eliminate this morning scramble to get showered, dressed and ready for work at the crack of dawn while also prepping kids for day care or school.

Stay in PJs. It's not just the time that it takes to get dressed for work – it's the cost. FlexJobs found that women's cost-savings associated with work attire are particularly substantial when the need to work in an employer's office is curtailed or eliminated.

One-quarter of women may save more than $1,000 per year through flexible work arrangements – and 5 percent may save more than $5,000, the study revealed. Men too can benefit substantially, with 15 percent saving more than a grand a year when working from home. To working parents with stretched expenses, shaving these costs can be particularly important.

The city of San Francisco, which is often in the vanguard of national trends and movements, is paving the way in these arenas for working parents. David Chiu, president of the City and County of San Francisco Board of Supervisors, has vowed to enact a law that would require local businesses to offer flexible work arrangements to employees. Under this proposal, business owners would need to have a process in place to handle employee requests for flex work if the employee is a parent or caregiver. Speaking on behalf of city Mayor Ed Lee, mayoral spokeswoman Christine Falvey was recently quoted in the SF Examiner as saying, "The mayor is supportive of policies that help working families in San Francisco and he will sign this piece of legislation."

Last week, the San Francisco Chronicle published a list of 18 local businesses already ahead of the curve for their policies to help working moms without being required to do so. The list includes LinkedIn Corporation, Morrison & Foerster LLP and the U.S. Department of Labor, San Francisco Region. In the article, Julia Parish, a staff attorney at the Legal Aid Society-Employment Law Center, notes: "The idea that there is somebody at home to take care of children and family needs is just wrong. The vast majority of mothers in San Francisco work … and only 13 percent of working moms work less than 40 hours a week, so (having flexible schedules) is a huge need. It has health impacts, gender equality implications, and it can help keep businesses and employees productive."