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Are dedicated bus lanes a good idea?
Why BRTs and dedicated bus lanes don't work everywhere and every time
On June 27, a young Parisian of Algerian descent illegally plied one of the city’s dedicated bus lanes, spurring a chain of events that led to a police chase, a fatal shot and an outburst of riots, the worst France has seen in more than a decade.
While France deals with this incident and the ensuing socio-political chaos at hand, I started to ponder on the genesis of the story and its relevance for urban mobility.
Are dedicated bus lanes necessary and do they serve any real good use?
Welcome to the twelfth issue of 2 cents on a coin!
Just as my life in the past half year has taken some big turns, this newsletter will as well. 2 cents on a coin will move beyond crypto topics, to share my take on transportation, new tech & the art of asking questions. I am excited to write and can’t wait to see where this takes us!
Dedicated bus lanes have been around since the 1940s in America and were established in the 1960s in Europe (Germany)Since then, well-meaning governments and transport authorities worldwide have established dedicated bus lanes to prioritize the movement of mass public transport. Forming the core of bus rapid transit (BRT) systems, dedicated bus lanes are set up to allocate road space specially for mass transit buses. BRTs took off in South America with Brazil implementing the Rede Integrada de Transporte in the 1970s. Today, the longest BRT network and the first in Southeast Asia (which opened in 2004) is operated in Jakarta, Indonesia. Africa’s first BRT system was opened in Lagos, Nigeria in March 2008.
The main principle of dedicated bus lanes and BRT systems is to move more people faster along roads
If we start from this premise — that the dedicated bus lane serves a purpose with 2 elements — moving more people, faster, then we can begin to interrogate its effectiveness in achieving this purpose by asking the question: “Do dedicated bus lanes help to move more people in a given city more quickly than alternative modes of transport?”
It almost seems like a futile exercise to explore the first aspect - whether buses move more people per unit of available road space than cars but I wanted to be sure. Just how much of an advantage does the average single-decker seater bus which seats 40 people have over the 5-seater sedan (e.g. the Toyota Corolla) in carrying people? If one needs eight 5-seater sedans to commute 40 people, how much road space is used up by those cars, and how is that compared to the road space used up by a bus carrying 40 people?
The answer? A single-decker bus can seat 4 times more people per unit of road space than the average sedan.
Most of the coverage regarding the effectiveness of buses over cars demonstrates the idea of fitting the equivalent number of cars into a bus to compare the capacity of a bus versus a car. However, it’s more practical to think about the cars as being on the road to account for the safe driving distance vehicles must keep between themselves. This safe driving distance is on average 1.8 metres for vehicles moving in slow motion (according to the 2-second rule)
Without accounting for safe driving distance, the bus seats 3 times more people per metre (because it has less un-utilised space within the vehicle compared to cars) but considering safe driving distance between moving vehicles, the efficiency of the bus increases to 4 times more people per stretch of road than the car.
So it is proven, if we have one unit of road space, and buses and cars operating at full capacity, it is better to give the right of passage to the buses since 4 people will move per stretch of road for every 1 person a car will move over the same stretch. (The efficiency of a bus can even double when you consider standing capacity which the car does not have)
But this only applies if the buses & cars are at full capacity. If a bus operates at a lower capacity than the threshold, it does not fulfil the criteria for having special right of way on a given road. At a utilisation of less than 23.6%, which is less than 9 people in a 40-seater bus, the bus becomes equivalent to the car in road use efficiency. Therefore at this level of utilisation or less, dedicated bus lanes should be open to both buses and cars.
A 40-seater bus carrying less than 9 people is equivalent to a 5-seater car at full capacity in terms of passenger transport efficiency.
So far, we have considered the prioritisation of a bus versus a car for the right of way, to meet the aim of moving more people, faster and determined that this right of way will only be effective vs a full car if the 40-seater bus is carrying more than 9 people at the given time. But what happens when the bus is not present and we have only cars on the road, should a priority lane still be reserved which the cars are not allowed to ply? The obvious answer is, No. However, here lies the problem with many ambitious BRT systems today. Many dedicated bus lanes of BRTs are fully dedicated to buses throughout the day, even when the bus lanes are empty and other parts of the road are clogged with traffic. It’s not uncommon to see hefty fines and high-profile scandals (like that of Nigerian TV newsman, Rufai Oseni) for road users contravening the bus lane rules.
The BRT system is based on the principle of providing unhindered road access to mass transit buses over other smaller-capacity vehicles to move more people faster. The key phrase is “over other vehicles”. BRT policies like those that restrict cars and smaller vehicles from the usage of the BRT lanes at all times even when there are no buses on the road can create unnecessary restrictions on the movement of people in other vehicles and have a net negative effect on mobility. The BRT concept works when one has buses & cars both vying for road space at the same time.
Governments and transport authorities will need to be more innovative about its implementation to establish a BRT system with dedicated lanes that serve the purpose of moving more people faster in a city. Dedicated bus lanes will need to be set up dynamically - in such a way that they become dedicated to buses and open to other vehicle types based on both the presence and capacity of the buses versus the other types of vehicles at any given time of the day in the city. For example, a proper dynamic BRT system will have dedicated lanes only at peak bus times when bus utilisation is high and above the threshold. An even more integrated approach will involve building automated barriers that open or close car access to dedicated bus lanes in real time based on how full a bus is and whether there are any buses on the road at all.
A dedicated bus lane in theory can generate significant gains in mass mobility and public transport, however, it may also become a contributor to a city’s handicap if the roads are constantly clogged with cars in traffic on one side while the bus lane hardly sees any buses or if the buses which ply the dedicated lane are underutilised.
In essence, for optimised mobility in a city, it is better to have no bus lane at all than to have an underutilised one.