These railroad officers are usually employees that work directly for a railroad company. They protect railroad property from trespassers, theft, terrorism, and espionage, while investigate crimes involving the company and their customers. They enforce state and federal laws. They also are often expected to handle hazardous material incidents as well. Depending on the company, they are assigned a region of the country.
For example, Union Pacific Railroad only assign a few agents out of offices in Dallas and Fort Worth, Texas. These positions are given large areas of responsibility that cover response for calls into Louisiana, Oklahoma, Kansas, and New Mexico. They usually have to rely on local police who are quicker to get on scene. But they will gladly help when they can.
Whereas, BNSF Railroad hires and assigns their people more locally in the DFW metroplex. They have large facilities that are often assigned officers that just act as security for that site. So, each company is different.
Transit Police are often officers that focus their services along transit routes and around transit facilities. Some may ride trains and buses in a uniform. Some may patrol in vehicles in a particular area. Others may work undercover looking for crime at bus stops, rail stations, or on vehicles. Or, they may be in a special unit, such as a motorcycle or traffic enforcement officers in HOV lanes or along special bus lanes. Or, bicycle patrol in Downtown areas. They serve a special purpose and often call local officers to deal with issues that don’t affect the transit system. But, some agencies have more responsibility than others. Regardless, their purpose is to make the transit system a safe environment for the customers that use it.
The short answer to your question is that transit police do everything the regular police do, but in a specialized environment (just like campus police!) I don't know about railroad police. I will talk about airport police and city transit (bus) police.
Transit police are primarily tasked with protecting transit property, employees, customers, and others on transit property. This would include buses, as well as the transit stations. In cities that have commuter rail, it would include those facilities. So, you could be riding trains or buses, driving a vehicle patrol and responding to calls at transit facilities or to help a driver with an unruly passenger, or even have a foot or bike patrol assignment.
I worked at the San Antonio Airport. It was pretty boring, most of the time. That means, it was peaceful, and we did not have a lot of police activity. Some of what we did would be considered "security." We did a lot of traffic control. And a lot of foot patrol. The types of calls we would get would vary. Some examples:
- An aircraft emergency landing because the plane hit turbulence and 22 people needed medical treatment. But, it was an international flight, and the pilot was not allowed to open the door unless Customs was there. Our Customs office was closed, with no agents on premises. (a quick phone call resulted in verbal authorization to proceed with emergency services.) This took 3 hours, as they all came off on backboards, and planes are really cramped!
- A guy who went through a security door and boarded an aircraft, locking himself in the bathroom.
- A guy who threatened to kill the President. (this of course resulted in calling in Secret Service).
- Narcotics trafficking arrests.
- Various weapons arrests, usually from things found by the TSA inspectors.
- Domestic disputes. Couples who were not getting along. One would grab the child and try to fly out. The other would try to stop them.
- Traffic Accidents
- DWI, disturbances, etc.
- Crowd control
- Dignitary protection, escorting protected witnesses, etc.
- Handling mentally ill persons, including doing "emergency detentions" to get them the evaluations and care they needed.
It was fun, especially getting to drive on the airfield and talk to the tower! If we were patrolling the terminals, we'd visit with employees and the travelers. You met someone different every day!
Let me know if you have any more questions!