In addition to the alternatives to driving alone that you can explore on this site, you may also consider adjusting your work schedule.
Note that these options are meant as suggested alternatives to driving alone, and that any and all changes to your work schedule must be discussed with and approved by your supervisor.
Compressed Work Schedule
Working a compressed work week may be an option depending on your particular position and the needs of your department. The most common compressed schedule for full-time employees is a 4x10 schedule (4 days a week, 10 hours per day), and a number of variations exist for part-time employees. This cuts down how many days you have to make your commute.
If you're seeking an alternate work arrangement to help reduce your commute and impact on the environment, UW Tacoma HR can help. Visit their website for more information on proposing a new schedule or work arrangement, including questions to consider before going to your supervisor.
Supervisors may also find resources on managing employees with non-traditional work arrangements.