Since President-elect Donald Trump considers New York City his home, the Secret Service and NYPD will surely continue the lane closures on Fifth Ave.

The 21st Century has not been kind to the New York City commuter. In 2001, 9/11 caused massive road, bridge and transit closings. In 2003, the Blackout stranded millions in the city. Sandy flooded subways, roads and tunnels in 2011.

Just when you thought you saw it all, here comes TRUMP-LOCK and it is yuuuge!

President-elect Donald Trump calls New York his home, and I don’t see that changing much after he takes the White House. His base is, of course, Trump Tower at Fifth Ave. and 56th Street. The NYPD and Secret Service will continue to close lanes on Fifth Ave. for the foreseeable future. Whenever there are protests, a section of Fifth Ave. will most likely be closed to traffic and this may extend to both 56th and 57th Sts.

How disruptive is this and how widespread is the impact you ask? Here’s a rundown:

– Fifth Ave., along with Madison Ave., is the most heavily used bus corridor in the city, with 23 bus routes from all five boroughs carrying more than 6,000 people on 130 buses in the peak hour. When Fifth Ave. has been occasionally closed for parades and such, buses are typically rerouted to the very narrow and overloaded Lexington Avenue. Imagine this happening every day, adding 30 minutes or more to a commute. I fear some of the outer borough passengers will switch to cars aggravating the situation.

Any protest outside the Trump Tower will most likely result in the closure of section of Fifth Ave. — maybe even 56th and 57th Sts.

– On a typical day, about 25,000 motor vehicles use Fifth Ave. Drivers will be diverting to Park and Seventh Ave. Adjustments of this magnitude create a domino effect — as Park and Seventh become overloaded, drivers already on those avenues will divert further west and east. To the east, Lexington will have the bulk of the buses so drivers will topple to Second Ave. — oy vey!

– Crosstown traffic may fare even worse. All the traffic forced off Fifth will have to use a crosstown street to get to another avenue. Westbound turns are limited by Central Park so Central Park South and 57th St. — if it’s open — are pretty much the only alternates south of 66th St. Fifty-sixth and 57th Sts. are major crosstown access roads to the Ed Koch Queensboro Bridge. Losing them will simply overload 58th and 59th Sts.

– Whenever the President returns home, travels to an airport, to a restaurant or to the U.N., “freezes” will be imposed on Fifth Ave. — meaning nothing, not even pedestrians, can move. My guess is the Secret Service will require direct access to Trump Tower for the President, meaning 56th St. will be reversed westbound just for POTUS.

– Traffic even before Trump is the worst it has been, perhaps in history. Uber, Lyft and others are part of the problem. We’ve already seen two consecutive years of traffic growth to Manhattan; this year is running almost 4% higher than 2015. We also face the crises of the L train shutdown during Trump’s first term, the possible loss of a rail-tunnel tube to N.J. and the expected surge in rebuilding East Midtown near Grand Central.

154 photos view gallery Protests erupt around the country after Donald Trump is elected president

I can go on and on with secondary and tertiary impacts, but you get the picture. Underground will be, by far, the best way to go. So, with all this, what should the city and state do?

1. Convert Fifth Ave. from 59th to 55th Sts. into a bus-only street. The Secret Service would be happier having no vehicles, but buses are far more acceptable and controllable, and they only use the west part of the street. No stops permitted in the Trump-Zone.

2. Develop an alternate route program such as guiding Fifth Ave. drivers as far north as 86th St. to shift east to Park Ave. or west via a transverse road. Look at signal timing and parking changes to facilitate those movements.

3. Convert 59th and 58th Sts. into express corridors to the Queensboro Bridge at least from 3 p.m. to 7 p.m. This will mean removing parking, prohibiting some turns and changes to signal timing.

One solution may be to convert a part of Fifth Ave. into a bus-only street.

4. Add as many as 50 traffic agents to keep intersections from spillback (when cars are stopped in an intersection as the signal turns red blocking the perpendicular movement).

5. Introduce the MOVE NY plan I’ve been championing to reduce traffic. The plan lowers the tolls on all outer bridges from the Triborough to the Throgs Neck to the Rockaway bridges to the Verrazano by $5. At the same time, electronic charging would be added to the East River bridges (they were tolled until 1911) and to traffic entering Manhattan south of 59th St. The plans also adds time and distance charges to Ubers, Lyfts, yellow taxis and other livery services. Not only will this move traffic more swiftly but it will provide billions to offer drivers alternatives. I suggest using emergency powers to get this done ASAP.

New Yorkers are a resilient breed so I’m not too worried for the long term. We can get through this crisis, too. We just need to be smart about it.

Sam Schwartz, aka “Gridlock Sam,” is a transportation engineer with has over 45 years experience in New York City traffic. He has served as the city’s traffic commissioner and chief engineer. He is CEO of Sam Schwartz Engineering, an international transportation consulting firm.