Metro riders shouldn’t suffer in silence if their rail cars are hot. (Susan Biddle/ for The Washington Post)

11 a.m. Update: Metro announced Tuesday morning that because of the heat riders will be allowed to carry and drink water in the transit system through the end of Friday’s service. This exception to Metro’s no eating or drinking policy applies to water only in stations and aboard trains, buses and MetroAccess vehicles.

Original post:

The National Weather Service has issued a heat advisory for Tuesday afternoon, and the Capital Weather Gang says travelers should expect the temperature to be “boiling hot” into Saturday. Here are some tips for protecting yourself, whether you travel by transit or car.

These are some of the tips I’ve collected over long, hot summers.

* Riders can usually tell the difference between a car that’s warm because it’s hot outside and a car with an AC problem. I’ve seen riders on platforms pivot away from a car entrance as soon as the doors open, and they feel the air from inside. Also, the car probably won’t have too many riders aboard, because they’ve already followed step one and moved.

* If the Metro car is hot, don’t just sit there. At the next station, try another car. The cars have their own cooling equipment. On summer days when I’ve carried a digital thermometer from car to car, I’ve found variations of 10 degrees. (Last summer, the highest temperature I recorded on a digital thermometer was 95 degrees in car 5160 on the Orange Line. The all-time record is held by car 5121, where the thermometer hit 100 degrees in July 2010.

* Go to one of the rail car intercoms and tell the operator the car is hot. The operator will call that in. Metro has maintenance staffers along the lines so they can board the cars and try to fix the problems. A hot car is a sufficient emergency to use the intercom. Riders also can call in the information about heat problems to Metro’s customer service phone, 202-637-1328. Remember the car number. (Some rail operators have disabled emergency intercoms on trains. It’s unclear how often that happens, but it should never happen. Make sure you get a response from the operator. If you don’t, report that to the customer service line.)

* If a train car’s doors don’t open when it reaches the platform, it may well be that maintenance couldn’t fix the problem on the go and sealed off the hot car.

* The age of the rail car isn’t a good predictor of the AC quality, though I’ve rarely encountered a temperature problem in the newest cars, the 6000 series. In past summers, many riders have complained about the 5000 series cars, and it was aboard those that I recorded the hottest temperatures.

* Above ground, the sunlight shining on one side or the other of a train makes a big difference in the temperature.

* The rail cars are never going to feel like the inside of your home or office with the AC on. There are three doorways on each side of the car to suck in hot air and release the cool. Trains that have recently entered service tend to be warmer, because the air conditioning hasn’t had a chance to take effect.

* In the stations, the wide open entrances, the presence of hundreds of passengers and the trains pushing warm air ahead of them all contribute to the heat.

* The last underground station before the line goes above ground can be just ghastly. That’s true at Union Station and at Ballston, for example. Others have configurations that put the platform close to a cascade of warm air. I found that true at Eastern Market.

* Temperatures within the stations also vary. Move around. In one of the portal stations, like Union Station, it may be slightly cooler on the side farthest from the outside air. During the summer, Metro puts big fans on some hot platforms. It can help.

* If a very long escalator is stopped, don’t try to walk up it. See the station manager.

* On any of our rail systems — MARC, VRE or Metrorail — the line operators may order the trains to slow down for safety, because heat kinks can develop in the rails.

These are some tips from AAA for auto safety in the heat.

* Avoid breakdowns by checking the car’s coolant tank and radiator, hoses and belts, tires, oil, battery, air and fuel filters.

* Have these items in the car, in case you do break down: flashlight with extra batteries, warning devices, such as flares or reflective triangles, first aid kit, a fully charged cell phone.

* Don’t even think about leaving the kids or the elderly in a parked car. And don’t forget the pets.

* Carry liquids for yourself and the others in the car. Encourage your passengers to drink more than their thirst requires. Children dehydrate much faster than adults.

* After returning home, always remove the child first before removing the groceries and shopping bags.

* If your child is in day care, make sure the center and workers have a plan that safeguards children from being left alone on buses, vans or in cars.

* If you spot a child locked in a car on a hot day, call 911 right away.