If you're planning to take in Saturday's Pride parade in Halifax, be warned: you won't be able to cross the Macdonald Bridge to get there and there will be no additional ferry crossings.

The bridge will be closed this weekend as tens of thousands of people pour into the city's downtown for the 30th Halifax Pride parade. And with Prime Minister Justin Trudeau showing up, it could mean many more people than last year's estimated 100,000 attendees.

The Macdonald Bridge will be closed from 7 p.m. today until 5:30 a.m. Monday so crews can install the first of four expansion joints.

Alison MacDonald, communications manager with Halifax Harbour Bridges, said it's necessary work that's been scheduled for months.

"We understand that it's Pride week and there's lots going on in Halifax, but it is unavoidable. We have to get these installed," said MacDonald.

Manufacturers flying in to oversee work

MacDonald said the manufacturers of the parts being installed are flying in this weekend to oversee the work, so it can't be delayed.

The sidewalks and bike lanes will remain open on the Macdonald Bridge. The MacKay Bridge will also be open.

The Macdonald Bridge will close again the following weekend during Rendez-Vous 2017 Tall Ships Regatta from July 29 to Aug. 1.

Organizers of the regatta that comes to town once every four years estimate this year's visitor numbers will surpass the 600,000 who took part in the past.

The new expansion joints will help the bridge expand and contract and are part of the multi-year Big Lift project that's caused headaches for drivers, cyclists and pedestrians.

The Macdonald Bridge will still be open to bikers and pedestrians over the weekend. (CBC)

MacDonald said there's no good time to do the work when every weekend is busy in the summer.

"We were always going to be installing these expansion joints in July and August and we regret that it's going to cause people to have to take the MacKay or find another route, but we have to get them installed," said MacDonald.

No additional ferry service

A spokesperson for the municipality said there will be extra buses on the roads to help deal with the anticipated volume of people, but the ferry will continue to operate on its regular weekend schedule.

On weekends, the Alderney ferry runs every 30 minutes, whereas on weekdays, it runs every 15 minutes for much of the day. The Woodside ferry does not operate on weekends.

Municipal spokesperson Nick Ritcey said the municipality decided not to implement the weekday schedule on the upcoming busy weekends because staff believe the usual weekend service, as well as the extra buses, will suffice.

Halifax Transit will keep its usual weekend ferry schedule during the Pride parade on Saturday. (CBC)

"They don't anticipate that there's a need to do that based on the volume on a normal Saturday versus the volume on this Saturday," Ritcey said. "They would just look at it and say, 'Can we handle this volume based on this schedule?' And the decision is yes."

The city has issued a transit disruption schedule that notes the bus routes impacted by the bridge and street closures.

Ritcey urged people who are relying on transit this weekend to check the city website "to make sure their route hasn't been affected and if it has been affected to make the proper travel arrangements."

The parade route that begins on Upper Water Street will be closed to parking beginning tonight and closed to traffic beginning tomorrow at 12:30 p.m.

The route will open again at 4 p.m. Saturday.

Big Lift on schedule

MacDonald said the Macdonald Bridge still needs underground infrastructure work and paving but the Big Lift project is on schedule to be completed by late fall.

"We want to get this project done as soon as we can so we can say the Big Lift is complete," she said.