With hopes of increasing the safety of those who hike up Half Dome, Yosemite National Park officials will limit numbers of weekend and holiday hikers through a permit system this year.

Half Dome long has attracted throngs of hikers -- some experienced, some not, some well-equipped for the task, some not -- and at times there have been accusations that the heavy, unregulated traffic to the top of the iconic dome has played a role in some accidents on the dome's steeply pitched shoulder. While Yosemite officials currently are working on a long-term management plan for the route to the top of Half Dome, until that is in place they are instituting a permit system for Fridays, Saturdays, Sundays, and federal holidays whenever the cables are up.

Under this temporary rule, no more than 400 permits -- costing $1.50 each -- will be issued on these days. For comparison sake, park officials say that fewer than 400 people typically try to reach the top of Half Dome during weekdays, while about 800 people, on average, used the trail on weekends and holidays.

If you're a good planner, permits are available up to four months in advance of your visit to Yosemite through the National Recreation Reservation Service. The permits are not available in Yosemite or on a first-come, first-served basis, park officials say. That said, backpackers "with an appropriate wilderness permit can receive a Half Dome permit when they pick up their wilderness permit with no additional reservation required. Rock climbers who reach the top of Half Dome without entering the sub-dome area can descend on the Half Dome Trail without a permit," the park said in a release.

The Half Dome Cables are usually in place and available for use the third Friday in May, conditions permitting. The last day to use them usually is the Monday of the Columbus Day weekend in October. However, park officials cannot guarantee the cables will be available on any given date, and so if you choose to get a permit for dates in May or October, there is an increased chance the cables will not be in place.

Furthermore, Yosemite officials say that if you are unable to hike Half Dome for any reason (including weather, cables not available, illness, etc.) on the day you have a permit, they will not be able to exchange the permit for a different date.

The park has posted a FAQ page here: http://www.nps.gov/yose/planyourvisit/hdfaq.htm

Here's the nitty-gritty for getting a permit:

If your hiking date is in May, June or July, the first day to get a permit is March 1. If your hiking date is in August, you can get one April 1; for September dates, May 1; for October dates, June 1.

You can apply for a permit through this site: www.recreation.gov, or by calling 877-444-6777 (or 877-833-6777 for TDD), or at 518-885-3639 if you live outside the United States and Canada.

Permits cannot be obtained via the mail.

You may only get four permits per phone call or website visit (you can call again or start over again to get additional permits).