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.
Bus rapid transit is a system of fixed-route public transportation used in urban areas. Unlike standard local bus routes, bus rapid transit (BRT) routes are optimized for faster service in areas with heavy traffic congestion. Some of the methods of improving service include operating buses on separate roadways or reserved bus lanes, realigning stops to provide faster express and local service, using access-controlled stations for fare collection instead of an onboard farebox, and traffic light preemption systems. BRT systems generally have an average speed greater than that of local bus routes, but slower than that of passenger rail systems.

BRT routes may incorporate separate roadways, often referred to as 'busways', or dedicated lanes on an expressway, to avoid congested local traffic. The South Dade Busway, operated by Miami-Dade Transit, connects the existing Metrorail system to areas in the southern end of the county using a separate roadway reserved for use for buses and emergency vehicles. The separate roadway used for this BRT system ensures that even the slowest of rush hour traffic cannot cause delays on the bus routes. The city of Adelaide, Australia uses a special bus guideway called the O'Bahn, which is equipped with steel guides to keep a bus centered on two concrete running rails via pilot rollers on the chassis. On this dedicated guideway, the buses can be operated at speeds of up to 100 km/h.

BRT does not necessarily require separate roadways. Some systems, such as the Orlando Lynx Lymmo, provide service to downtown stops on dedicated bus lanes. Traffic signals along the Lymmo route are equipped with automatic preemption patterns to ensure the buses are not delayed by red lights. The downtown Lymmo service thus has priority over other traffic present on the streets. Additionally, highway service can be implemented using special dedicated High Occupancy Vehicle and bus lanes on expressways.

One of the advantages of separate roadways and dedicated expressway lanes for BRT use is that special stations can be used in place of roadside bus stops. These stations can have fare control systems such as turnstiles in place as a replacement for onboard fare collection, which can be a major bottleneck in the boarding and unloading of passengers. The elimination of onboard fare collection greatly reduces the time spent at each stop.

How fast does a bus rapid transit system operate? This varies greatly based on many variables, including the number of stops, whether or not the bus is operating on public roads, and how fare collection is handled. I've personally observed the average speed of the local bus routes in Miami-Dade County to be roughly 11 miles per hour at off-peak hours and 6 miles per hour (ouch!) during rush hour conditions. Buses on the South Dade Busway seem to average about 15 miles per hour independent of the time of day. This may not really be all that rapid, but it's a lot nicer than an average of six miles per hour. I generally consider this to be a successful system.

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