The North Washington Street Bridge, also known as the Charlestown Bridge, is an essential connection between Charlestown and the North End.

The bridge is owned by the city of Boston, which currently spends between $3 and $5 million a year to maintain the functionality of the deteriorating structure.

MassDOT said the proposed design will provide improved vehicle, pedestrian, cycling, transit, and boat navigation facilities, while visually complementing the iconic Zakim Bridge.

MassDOT said the proposed bridge will expand the currently narrow sidewalks to provide a safer environment for pedestrians, including architectural design elements, plantings, information plaques, lighting and improved treatments for the Freedom Trail.

Separated cycle tracks on either side will create a safer connection across the Charles River for cyclists.

Two vehicle lanes will be provided in either direction, in addition to a bus only lane in the southbound direction.

The proposed design will also create a more open channel for boats, while maintaining flood control measures associated with the Charles River locks.

MassDOT previously said construction of the project is anticipated to begin either in late 2017 or early 2018 and continue to 2020, using accelerated construction techniques.