PHILADELPHIA (CBS) — SEPTA workers  are officially on strike. The organization has released a contingency service plan for travelers to adjust their plans.

The Transport Workers Union Local 234 authorized the strike earlier this month. After weeks of negotiating the two sides were unable to reach an agreement. Now bus, trolley and SEPTA subway lines for almost 1 Million commuters are not operating. Regional Rail  continues to operate but it’s likely riders will still feel the effects of the strike, as many SEPTA customers may look to it as a back-up.

Officials say service may be adjusted as needed such as adding stops to Express trains in order to accommodate impacted riders. Septa has a service line interruption guide here.

The biggest impact is expected during the morning and evening commutes. As a result, Regional Rail riders who board between 2:45-7 p.m. at Temple, Jefferson, Suburban or 30th Street and University City stations will be asked wait in line at the concourse level to avoid overcrowding on the train platforms. And those riders will have to purchase a ticket or pass at a SEPTA sales window before boarding if they don’t already have one.

SEPTA is strongly encouraging area businesses to adjust work hours or institute flexible schedules should the strike happen.

Students who go to school in Philadelphia will also feel the impact of the strike. The Philadelphia School District and local college and universities released contingency plans below:

Schools OPEN

SCHOOL DISTRICT OF PHILADELPHIA: No School District academic calendar events will be changed as a result of the strike. With regard to the status of the SEPTA service interruption, please continue to check the District Website regularly. For more information please email transoperations@philasd.org or call 215-400-4315.  The District’s Facebook and Twitter accounts will also have up to the minute information.

TEMPLE UNIVERSITY

UNIVERSITY OF PENNSYLVANIA

DREXEL UNIVERSITY

UNIVERSITY OF ARTS: Working on plan.  Keep checking school website: www.uarts.edu and social media: @UArts for updates.

SAINT JOSEPH’S UNIVERSITY: Check school website & social media

COMMUNITY COLLEGE OF PHILADELPHIA:  Check school website & social media

PHILADELPHIA UNIVERSITY:  Check school website & social media

VILLANOVA UNIVERSITY: Should have minimal impact on students & staff

Whether the strike happens or not, SEPTA wants its riders to be prepared. Customers are advised to check out the online Service Interruption Guide.