BRT is an abbreviation for bus rapid transit, a recent mode of public transportation that is meant to elevate bus service to subway standards. BRT removes various disadvantages of bus service that make it inferior to subway service.

1. Frequency: Subways run every five to ten minutes while buses run every 20 minutes at their best and up to every hour at their worst. BRT dedicates a large fleet of buses to its route and schedules them to come at subway-comparable frequency.

2. Reliable arrival times: Subways have a single track all to themselves so unlike buses they don't get stuck in traffic. This means that every trip takes about the same time to complete and therefore the intervals between the arrival of one train and another are uniform. A subway rider can therefore truly expect service at regular intervals.

As for buses, because their travel times vary significantly with traffic, they can't achieve the same uniform time intervals. Therefore, one cannot depend on a bus to arrive every X minutes. BRT remedies this disadvantage of bus service by dedicating an exclusive lane for bus service so that traffic conditions do not create very irregular intervals between the arrival of any two given buses.

3. Speed of Service: Unlike subways, buses travel any given distance much slower. This is due to several reasons.

The most obvious one is that a subway train is able to travel without stopping because there's no heavy traffic. (There is some traffic so light it is almost negligent; the presence of another train ahead of the first one on the same track) Most buses, however, put up with a lot of traffic. This is especially true because most bus routes serve densely populated urban areas that get the heaviest traffic. BRT remedies this disadvantage by using a dedicated lane and avoiding traffic, as I have already mentioned.

But there other less obvious reasons that explain why a bus trip is slower than a subway ride that covers exactly the same distance. They include the bus's means of fare collection, its tendency to make too many stops and board passengers through elevated platforms that require climbing stairways. These limitations of the bus and the way BRT service remedies them are explained in depth below.

A. Fare collection: People who get on trains have already paid their fare when they entered the station. People boarding buses, however, drop their change into the coin slot one by one as they come in. For that reason, buses waste a lot of time standing immobile that trains do not. BRT remedies this situation by installing automatic fare collection systems at bus stations.

B. Number of stops: Trains have a much lower number of stops per mile than buses. A bus may have to stop twice in a period of seconds to pick up passengers at two stops less than a quarter of a mile distance from each other. To remedy this, a BRT system limits the number of bus stops so that buses spend less time picking up passengers and more time driving along their route. And that improves travel time for everyone.

C. Entrance method: A train's floor is on the same level as the platform. Hence: a passenger can walk into the train right through the doors. A bus, however, often forces passengers to climb a set of stairs to get onto the bus from the street stop. This means that buses must spend more time boarding passengers than trains. The BRT solution to this disadvantage of the bus is low-height buses that are level with the ground so that less stair-climbing is required.