Can Carpooling Unlock Better Bus Services?
Key Takeaways
- Bus prioritisation is essential to making bus services successful.
- When building new road infrastructure or widening roads to three or more lanes, dedicated bus lanes or High-Occupancy Vehicle (HOV) lanes are often created, including carpool lanes.
- However, decision-makers shy away from removing a general traffic lane and installing a dedicated bus lane when there are only two lanes to begin with.
- Decision makers are afraid of a backlash from going straight to a dedicated bus lane and doubt that it will lead to a significant reduction in demand.
- To deliver better bus services, we should take a more incrementalist approach, leveraging carpooling and other strategies to create an HOV lane without sparking community backlash.
- If implemented well, this can make it a smaller step in the future to create a fully dedicated bus lane, or if justified, a light rail.
What Next?
Can you use an incremental approach to deliver improved bus priority?
Introduction
Picture this: you're at a bus stop, watching your bus approach through traffic. The bus inches forward, trapped behind a sea of single-occupancy vehicles. You could have walked faster.
This scene plays out thousands of times a day in cities around the world. We know the solution: dedicated bus lanes that keep buses moving freely. Transport planners know it. Even politicians know it.
So why don't we have more of them?
The answer isn't about policy. It's about politics.
As a transport policy geek, my mantra when developing solutions is "what is the right policy, and how can we make the politics work?" Bus lanes are a perfect example of good policy where the politics often doesn't work. Most transport strategists would say we need far more dedicated bus lanes. The reason we don't have them is simple: it's politically difficult to remove a general traffic lane in favour of buses.
The political barrier becomes almost insurmountable when you're asking decision-makers to convert a two-lane road into one lane plus a bus lane. That's a 50% reduction in general traffic capacity. Even when sophisticated traffic models show this won't create the gridlock people fear, politicians balk. They don't trust the models. They fear the backlash. So nothing changes.
But what if we didn't need to make that leap all at once?
What if we could use carpooling and other tools as a bridge, a way to ease into bus priority without triggering the political resistance that kills so many bus-priority projects?
That's what this blog is about. It's about moving from a big-bang, all-or-nothing approach (it's a bus lane or it isn't) to an incremental approach that builds political support at each stage. It's about making the politics work so we can finally deliver the policy we know is right.
What is Carpooling?
Carpooling is the practice of sharing a car journey with others travelling in the same direction. Instead of four people making the same trip in four separate cars, they share one vehicle. It's a simple concept that has existed for decades.
Historically, carpooling has been hard to coordinate. You needed to know someone heading the same way at the same time, negotiate pickup arrangements, and hope your schedules aligned. These friction points kept carpooling rates low in most cities.
But modern technology has changed the game. Ride-matching apps, real-time GPS, and digital payments have made it far easier to connect drivers with passengers.
The Transport System Perspective
From a purely transport-planning perspective, carpooling presents a paradox. On one hand, fewer cars on the road is always good. On the other hand, carpooling done wrong can actually undermine our broader transport goals.
Problem 1: Competition with public transport. If carpooling is too convenient and cheap, people may switch from buses to carpools rather than from single-occupancy driving. The road has fewer vehicles, but the bus system loses ridership and revenue.
Problem 2: Induced demand strikes again. Let's say carpooling successfully reduces congestion by getting more people into fewer vehicles. Great! But here's what happens next: those clearer roads attract new drivers who were previously deterred by congestion. Within months, you're back to congested roads.
This is why transport planners have traditionally been ambivalent about carpooling as a standalone solution.
The HOV Lane Solution
However, there's a proven way to make carpooling work for, rather than against, public transport: High Occupancy Vehicle (HOV) lanes.
HOV lanes are restricted traffic lanes reserved for vehicles with multiple occupants, typically carpools and buses. They've been successfully implemented around the world, usually in two scenarios:
- When new road infrastructure is being built and HOV lanes are included from the start
- When converting one lane of a highway with three or more existing lanes
The beauty of HOV lanes is that they create an incentive structure that rewards the behaviours we want. Carpooling gets you into a faster lane. Buses get priority and improved journey times.
However, almost all successful HOV lanes have been implemented on wide highways or new infrastructure. The political barriers to creating HOV lanes by converting existing two-lane roads have proven just as formidable as creating dedicated bus lanes.
Carpooling as a Political Tool
What if we stop thinking of carpooling purely as a transport outcome and start thinking of it as a political strategy?
What if it's the bridge that makes the seemingly impossible conversion of two-lane roads politically viable?
Before I explain how, let me first dive deeper into why buses need priority in the first place and why it's so hard to deliver.
The Bus Service Challenge
Ask people why they don't take the bus, and two complaints often dominate: buses are slow and unreliable.
Both problems stem from the same root cause: buses share road space with general traffic.
Think about a typical bus journey. You walk to the bus stop and wait. The bus arrives (hopefully on time) and you board. Then the bus stops every few hundred meters to pick up more passengers. Between stops, it sits in the same traffic queues as every car. When traffic is heavy, the bus crawls.
The Solution: Bus Priority
The way to make buses competitive with cars is simple: give them priority.
This means two things:
- Priority at traffic lights - Buses get green lights faster or hold greens longer
- Dedicated bus lanes - Buses bypass general traffic entirely
When done comprehensively, this is called Bus Rapid Transit (BRT). Done well, BRT systems can make bus travel faster than driving.
Buses running in dedicated lanes with signal priority can match or beat car travel times while moving far more people per hour than general traffic lanes ever could.
The Space Allocation Fight
So if the solution is this straightforward, why don't we have BRT or dedicated bus lanes everywhere?
The answer is space.
The road space needed for a dedicated bus lane is currently being used by general traffic. Converting it means taking space away from cars. This is where the politics get difficult.
The easy case: 3 lanes to 2 lanes plus a bus lane
Many cities have successfully converted three-lane roads into two general traffic lanes plus one bus lane. This represents a 33% reduction in general traffic capacity, and while it generates some opposition, it's often politically achievable, especially during peak hours when buses carry the most passengers.
The hard case: 2 lanes to 1 lane plus a bus lane
Going from two lanes to one lane plus a bus lane is far more challenging. You're asking for a 50% reduction in general traffic capacity. To many politicians and members of the public, this feels like you're about to create gridlock.
Sophisticated traffic models often show that this fear is unfounded. When you reduce road capacity, something counterintuitive happens. Some drivers reroute to different roads. Some shift their trips to off-peak times. Some switch to buses (especially once they're faster) or other modes. The phenomenon that causes traffic to expand to fill new roads, induced demand, works in reverse. Call it "reduced demand" or "traffic evaporation."
The net result? The remaining general traffic lane often handles the reduced traffic flow reasonably well, while buses move far more people far more efficiently in their dedicated lane.
The Trust Gap
But this requires decision-makers to put their faith in the models.
Many politicians don't understand induced demand in the first place. They see new roads fill up with traffic and assume it's just because more people are driving, not because the new road itself generated that demand. If they don't understand induced demand, they're certainly not going to trust a model predicting "reduced demand."
From their perspective, the models are asking them to believe in magic. You're telling them that removing half the road capacity won't create chaos, and they simply don't buy it. The political risk feels too high.
So they say no. And buses stay stuck in traffic.
Some cities have solved this by creating parallel road hierarchies. One road is prioritised for buses and bikes, while a parallel road is prioritised for cars. This works well when you have parallel roads. In many cases, there simply isn't a viable alternative route nearby.
Breaking the Deadlock
So we're stuck. We know what needs to happen. But we can't get it approved because the political leap is too large.
This is where an incrementalist approach using carpooling comes in. Instead of asking politicians to make one giant leap of faith, what if we could break it into smaller, more manageable steps?
That's precisely what I'm proposing.
Leveraging Carpooling As A Way Forward
If the political problem is that converting a lane to bus-only is too big a leap of faith, we need to make the leap smaller.
Instead of going straight from two general traffic lanes to one general lane plus one bus-only lane, we create intermediate steps. Each step is politically more palatable than a full bus lane, but each step also moves us closer to the ultimate goal.
The Incrementalist Approach
An incrementalist approach has four potential stages. Not every corridor will need all four stages, and some might move through stages quickly while others take years. The key is that each stage is individually justifiable and politically viable.
Stage 1: Create a 2+ HOV Lane (Buses + 2-Person Carpools)
The first step converts one lane into an HOV lane restricted to vehicles with at least two people, buses and carpools of two or more.
This is fundamentally different from a bus-only lane. You're not telling drivers "you can never use this lane." You're telling them, "You can use this lane if you bring a passenger."
But we can't just paint new lane markings and walk away. If we simply mandate the change without support, we risk short-term disruption and political backlash that could kill the entire project. We need to actively help people adapt by making it easy to:
- Switch to the bus (preferred)
- Carpool with others
- Retime their journey away from peak hours
- Reroute to alternative roads
How do we make this work?
Improve bus services proactively. Don't just give buses a faster lane. Use this as an opportunity to increase frequencies, extend hours, or add new routes. When London introduced its congestion charge, it simultaneously dramatically increased bus services.
Offer temporary fare incentives. Consider temporary fare discounts for the first few weeks after implementation. This lowers the barrier for people to try the bus and creates habits.
Build a serious carpooling program. Don't assume carpooling will happen organically. Implement a proper car-pooling scheme using proven technology and lessons from successful programs elsewhere. This means real-time matching apps and designated pickup zones.
Enforce thoughtfully, not aggressively. None of this works if single-occupancy vehicles can simply ignore the restriction. Enforcement is essential. But it needs to be done carefully to avoid the backlash that has reversed camera enforcement programs in many jurisdictions.
Start with warnings. Give people two or three warnings before issuing fines. When you do start fining, start low and increase penalties for repeat offenders. Make it clear this isn't a revenue grab, and transparently dedicate fine revenue to specific purposes, such as funding improved bus services or fare discounts.
Communicate relentlessly. This is fundamentally a communications challenge as much as a transport challenge. Politicians need to lead. Months before any announcement, they need to start explaining the problem: buses stuck in traffic, inefficient use of road space, and the opportunity to move more people in fewer vehicles.
Stage 2: Increase to 3+ HOV Lane
If Stage 1 succeeds, you'll likely see a significant uptick in 2-person carpooling. That's good! But it can become a victim of its own success. If too many 2-person carpools start using the lane, buses lose their speed advantage, and the lane becomes congested.
At this point, you have two options: jump straight to a bus-only lane, or take another incremental step to a 3-person minimum (3+ HOV).
The 3+ requirement further reduces the number of vehicles in the lane while still allowing carpoolers to use it.
Stage 3: Price the HOV Lane
Another tool for managing demand is pricing. Convert the HOV lane into a High Occupancy Toll (HOT) lane, where carpools meeting the occupancy requirement pay a fee to use the lane during peak hours.
This is different from allowing single-occupancy vehicles to pay for access. The lane remains restricted to buses and qualifying carpools; pricing is simply a demand management tool to prevent overcrowding.
Dynamic pricing can keep the lane flowing freely even during peak periods. When demand is low, the price is low or zero. When demand threatens to congest the lane and slow down buses, the price rises to discourage marginal users.
The revenue can fund ongoing bus service improvements, creating a virtuous cycle.
Stage 4: Convert to Bus-Only (or Light Rail)
Eventually, you may want to convert to a full bus-only lane, or even a light rail corridor if demand justifies it.
Here's where the incrementalist approach pays dividends. Because you've been gradually shifting the mix of users over months or years, the number of people negatively affected by this final conversion is much smaller than if you'd tried to do it all at once.
Yes, regular carpoolers will lose their time advantage. That's a real political cost. But if you've implemented Stage 3 pricing, many casual carpoolers have already been priced out, leaving primarily buses in the lane anyway. The conversion to bus-only becomes a smaller step.
There's also a risk that removing carpool access leads to more single-occupancy driving, worsening congestion in the general lanes. This is a genuine concern and needs to be weighed against the benefits of giving buses complete priority.
Is an Incrementalist Approach Viable?
Incrementalist approaches have a significant vulnerability.
They require sustained political commitment across multiple decision-making cycles. That means surviving changes in government, ministerial reshuffles, staff turnover in transport agencies, and shifts in public priorities.
What happens when your champion gets promoted, retires, or loses an election? What happens when a new government comes in with different priorities?
You could get stuck.
This is a real risk. Policies that depend on sequential decision-making over years are vulnerable to political winds. We've all seen examples of ambitious long-term plans that stalled halfway through when priorities shifted.
But Consider the Alternative
The alternative to an incrementalist approach isn't successfully implementing full bus lanes. The alternative is doing nothing.
Look at the status quo. Many places have needed bus priority for decades, but nothing has changed.
Why? Because the political leap to full bus lanes is too large. Decision-makers won't take that leap, so we remain paralysed.
An incrementalist approach that gets stuck at Stage 1 or Stage 2 is still vastly better than remaining stuck at Stage 0.
The Value of Partial Success
Let's say you implement Stage 1 and never get beyond it. You've still achieved:
- Significantly faster bus journey times
- More reliable bus services
- Increased carpooling, meaning fewer vehicles on the road
- More efficient use of road space (moving more people per lane)
- Demonstrated that the sky didn't fall when you reallocated road space
- Built public acceptance for prioritising people-moving over car-moving
Perfect shouldn't be the enemy of good.
Conclusion
The challenge of improving bus services through dedicated lanes doesn't have to be an all-or-nothing proposition. By using a range of tools, including carpooling as a bridge, we can create a politically viable pathway to the bus priority infrastructure we desperately need.
Yes, an incrementalist approach carries risks. Progress depends on sustained commitment across multiple decision-making cycles and changes in leadership. You might get stuck at Stage 1 or Stage 2 indefinitely. But consider the alternative: in many places, the perfect has become the enemy of the good.
An incrementalist approach that leverages car pooling and other tools offers a way forward. Even if you never reach Stage 4, a well-functioning HOV lane still moves more people more efficiently than general traffic lanes while giving buses significant journey time improvements.
Sometimes the right policy requires making the politics work, even if that means taking the scenic route to get there.