BOSTON (WPRI) — The first test of the Massachusetts Bay Transportation Authority’s “unprecedented” month-long shutdown of the Orange Line begins Monday.

It’s the first workday commute since the shutdown between Oak Grove and Forest Hills, which began Friday night and resumes at 5 a.m. on Sept. 19. The line will be replaced by commuter line trains and 200 shuttle buses.

The commute is expected to be messy even though plans are in place to navigate through the shutdown.

It will not only affect subway riders, but it will also have a huge impact on the Boston area for anyone who drives, bikes, or even walks because of the added traffic from shuttle buses.

“This is a necessary and significant amount of work we need to get done and it doesn’t come without inconvenience, but we believe at the end of this period of time, with everyone’s support, we will be better for it,” said James Tesler, Secretary of Transportation for MassDOT.

The MBTA created a guide for riders that shows them alternate routes they can take for the 20 Orange Line stations that will be affected by the shutdown.

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MassDOT also created a map warning drivers where they can expect gridlock traffic around the city. Part of the reason will be because those who rely on the MBTA will start driving if they have a car.

Additionally, some major roads in the city will be divided in half — one side for the MBTA shuttles and the other for cars — which will also cause congestion.

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Also starting on Monday, parts of the Green Line will also be closed for 28 days. The shutdown from the Union Square to Government Center stations will allow the MBTA to perform the final-phase construction work necessary to open the Medford Branch, which is anticipated to open in late November.

The decision for the Orange Line shutdown comes just weeks after flames and smoke were seen coming from an Orange Line train causing some riders to climb out windows and even one passenger to jump off the bridge into the river.

The Federal Transit Administration launched a review of Boston’s subway system in April following several accidents that led to injuries or death within the past year.