» Evidence suggests expanded rail operations produce higher ridership gains than more bus service.
In researching the article I wrote last week for the Atlantic Cities on bus rapid transit (BRT), I wanted to provide a basic piece of evidence that offered support for the idea that typical bus operations were not offering the sort of service that attracted riders effectively. My sense (hardly a unique perspective, of course) was that bus services in cities around the country are often simply too slow and too unreliable for many people to choose them over automobile alternatives. Rail, particularly in the form of frequent and relatively fast light and heavy rail, may be more effective in attracting riders, but so might, the article hypothesizes, BRT services, which provide many of the service improvements offered by rail.
To provide such evidence, I compared ridership growth between 2001 and 2012 on urban bus and rail services on the ten U.S. transit networks that had rail routes in 2001 and did not expand them significantly during that period, as shown in the following chart. I excluded cities with rapidly growing rail networks, such as Los Angeles or Portland, under the presumption that the installation of a new rail line may result in a considerable shift from bus to rail simply because of changes in service patterns resulting from the opening of that line (e.g., riders may be encouraged to take rail rather than bus because certain bus routes are eliminated or re-routed with the opening).
The chart’s data — based on a limited sample of information — show that nine of ten urban rail and bus systems saw higher ridership gains along their rail routes than their bus routes (or less loss). The only exception noted here is Buffalo, whose bus routes saw a higher jump than the city’s light rail line. The conclusion we can take from this compelling, if limited, data point is that rail services do seem to be providing a greater benefit to passengers than buses do.*
Similarly, as the following chart demonstrates, when evaluating growth of ridership by mode as a share of overall system growth, the evidence suggests that rail lines, new or not, are more effective in contributing to building overall transit ridership than bus services (a slightly different metric than the above chart, which simply compares ridership by mode in 2001 with same-mode ridership in 2012). Of the 27 systems shown here, the rail lines of 22 of them contributed a higher proportion of ridership growth than the bus lines.
(To explain this graph, imagine a hypothetical transit system with 100 million riders in 2001 and 120 million in 2012. Of that 20% growth, 15 million additional riders can be attributed to rail and 5 million to buses; this would produce a 15% “contribution” from rail and 5% contribution from buses, which would be graphed here. In a real-world example, Boston’s MBTA increased its urban ridership from 314 million in 2001 to 360 million in 2012; of that growth, 41.4 million riders were added to rail and 3.7 million were added to bus lines. Therefore rail produced a 13% “contribution” (i.e., 41.4/314) and bus a 1% contribution.)
There is no question that this conclusion about the relative merits of rail in inducing ridership increase is a frequently promoted idea among advocates for rail expansion. A quick review of ridership changes in many major cities is enough to articulate this point. For example, as the following chart shows, in Chicago, Philadelphia, and Los Angeles, the rate of ridership increase on rail services (not including commuter rail) has been far higher than on bus services over the past decade.
This comparison, however, is not adequately to say definitively (if a blog can ever do so) that rail produces more effective ridership growth than bus services. It doesn’t take much investigation to find that between 2001 and 2012, Los Angeles dramatically expanded its rail network, adding two new light rail lines. Meanwhile, though Chicago’s ‘L’ rail network saw no extensions, bus services were curtailed dramatically thanks to a difficult funding environment resulting from the recession.
What, then, is the interplay between a city’s investment in added transit services by bus or rail and the resulting ridership changes by mode?
To begin to evaluate this question, I compared the ridership data presented above (from the American Public Transportation Association) with vehicle revenue hour data (from the National Transit Database). Vehicle revenue hours can be used as a proxy for service provided.** In theory, if no other variables change, an increase in revenue hours should result in increasing ridership, simply because people are more likely to ride if frequencies are higher. Response to increased service, though, may vary depending on whether bus or rail services are being altered.
The following chart shines some light onto this question by considering the 27 transit systems mentioned above. The x axis indicates the change in bus or rail revenue hours as a share of total change between 2001 and 2012; the y axis indicates the change in bus or rail ridership as a share of total change.
The linear correlation between service increases (or declines) and ridership change is stronger for rail services (r-squared of 0.51) than buses (0.40) for this admittedly limited sample. But the overall conclusion, illustrated by the trendlines, seems to show that increasing revenue hours on rail produces higher ridership gains than on buses. The trendlines indicate that, on average, a 20% increase in revenue hours would produce a 10% increase in bus ridership and a 27% increase in rail ridership. In other words, rail appears to be more than twice as effective in generating ridership growth than traditional bus service.
I reexamined these results with a different time period, from 1996 to 2007, comparing changes in bus and rail service hours with ridership. These comparisons (among a smaller sample of 22 systems, most of them the same) provided a similar result, though with stronger correlations and even stronger evidence of ridership response to rail service growth versus bus service growth. In both cases, rail service improvements produce higher-than-proportional increases in ridership on average whereas bus improvements produce lower-than-proportional increases in ridership.
This review provides a preliminary and small-sample look at the relative attractiveness of bus and rail services. Clearly these data cannot be extrapolated to assert a “guarantee” that rail service improvements are more effective in generating ridership than bus service improvements. Moreover, other factors, such as changes in bus routes in response to rail openings or other changes, must be considered but are not here.
But these data do at least imply that there is a strong preference for rail services over bus, and that from a policy standpoint, ridership is more likely to grow with increases in rail service. Riders respond when they’re offered better service!
* I do not consider the impact of BRT lines in this analysis (which, you might note, should put at least an asterisk on the hypothesis I articulate in the Atlantic Cities piece) because of the limited BRT implementation thus far and the fact that most current “BRT” provides mediocre service improvements that do not parallel the advantages of rail.
** There are other metrics that can also be used to measure service provided, such as vehicle revenue miles or vehicles in service. In all cases, a “vehicle” is either a bus or a rail car. A train is made up of multiple vehicles.
47 replies on “Recent Trends in Bus and Rail Ridership”
Rail services provide higher capacity than buses – specifically, usage per revenue hour is higher for rail than for bus. If transit agencies were solely adjusting service to meet changes in demand, then rail will always seem to ‘create’ more ridership for a given chnage in revenue-hours.
Or to put more simply: you’ve shown correlation, but I’m not convinced the causation is the right way round.
I agree with this. If at all possible, I would try to frame this in terms of cost instead of service hours.
The relevant question is: given a limited increase in operational budget, where should the money be allocated in order to generate the greatest ridership growth? One service hour for heavy rail presumably costs more than a service hour for a bus system.
It’s harder than changing the metric. Rail routes, almost by definition, are core routes in the transit network. These rail line receive the benefits of improved service on connecting routes without adding extra service to the rail line itself. Bus routes on the other hand are a mix of core routes and coverage routes for which additional ridership on the route is not expected for additional investment in service.
Yonah, this is interesting data, but I don’t think it’s much more useful as a demonstration of network effects than as a guide to policy.
I’m not compelled by higher-capacity-on-rail argument. Chicago L trains, for example, are 48′ long per vehicle, while Chicago artic buses are 60′ long per vehicle; they probably have similar carrying capacity. This is not always true, of course, but it’s worth keeping in mind.
I do agree that there is certainly a network-effects issue we have to evaluate. That said, I’m not sure that we would see higher ridership attraction on rail per added vehicle revenue hour compared to bus in cities without an expanded rail system, which we seem to see here. So that’s a bit of a mystery.
I’m certainly in agreement that this post is not enough to guide policy!
There aren’t any single-car long L trains though—they’re coupled into married pairs so the shortest trains are two cars long. I’m not sure about capacity for articulated buses, but it’s ~80-100 per car. And articulated buses aren’t on every Chicago route, either (IIRC, even some busy ones mainly use unarticulated buses).
The point was that a “vehicle” is defined as a rail car, not a train, so the relevant comparator is one rail car to one bus.
you can’t hitch two articulated buses together and double capacity. You can hitch two streetcars together and double capacity. If it has it’s own right of way and the blocks are long enough 4 can be hitched together. If it’s running off the street you can, like the L or subway hitch together 10 or 11. I think Chicago has a max of 8 and the NYC has a max of ten except on the Flushing line which runs 11 car trains. IRT cars are shorter than IND/BMT cars.
CTA is beginning to build platforms to berth 10 car trains–see the Wilson Av station rehab docs on the CTA site. The IND ran 11 car trains on the E,F routes in the 50s–cut back to 10 account labor issues.
Far more important are 1 a single CTA employee runs the 8 car trains whose cars last at least twice as long as any bus, and 2 even w/ the abysmal track conditions from years of deferred maintenance, the L is still faster than any express bus.
What CTA needs to do next is put solar panels on the station roofs.
65 foot IND/BMT cars or 85 foot IND/BMT cars which is what are run today? IIRC the J/M/Z line is restricted to 65 foot cars. There have been longer and shorter cars on the system. The BMT articulateds for instance.
BMT cars maxed @ 67′. IND cars were built to a different BMT dimension of 60′. The longer IND/BMT “B Division” cars are 75′, and they are the ones which can’t be used on Eastern Division/JMZ tracks.
So the 11 car trains on Queens Blvd (E, F) were 60′ cars (R1-9) original IND cars.
Enough detail, point is, PATH and CTA are both thinking about longer trains (51’and 48′ cars respectively) because the headways are already tight and adding cars decreases the labor cost per riders.
11 cars at 60 feet is 660 feet and 10 cars at 75 feet is 750…. 90 feet longer with one less car….
Yes 10×75 = 750, BUT, NYMTA doesn’t have platforms that long. IIRC (from a discussion on SubChat.com) most IND platforms are 660 (11×60) although perhaps they could be lengthened as was done to older BMT stations in the 60s. The other problem is that the 11 car trains in the 50s had a second conductor by labor agreement and whether TWU would be willing tosee 11 car trains again w/out the third crew person is not trivial. Also an issue is that current MTA fleet is either married pair or more recently 5 car drawbared sets. While it is true that for the 7 Flushing (the only 11x 51 route) 5 car sets are being modified to 6s, this reduces flexibility as when any car in the “fixed” consists goes down the entireset goes to the shop.
Ultimately the good news here is that ridership is growing, how to plan/execute upgrades and extensions rather than how toreduce service because of deficits.
The wheel housings protrude into the bus and take up valuable floor space. A three-axle bus is even worse, so vehicle length between rail and bus is not quite comparable.
Tom – I don’t think that’s right because he’s measuring percentage changes. The greater vehicle capacity of rail is already built into the baseline.
A lot of systems with both buses and rail are using them for very different things, especially in the United States. Usually rail is providing the core of the system in the densest areas with the highest ridership, and buses are providing coverage service. Rail is also serving the job centers, in New York people may take buses within their own borough but typically will take the subway into Manhattan.
I thought “what is a city where buses are on primary routes and not just for coverage?” and Seattle came to mind, and yep, its one with a larger rise in bus ridership than rail.
Of course, it’s well documented *everywhere*, including Seattle in particular, that:
(1) buses suck for primary, core routes; they have too low a capacity, they bunch and end up with irregular service, etc.
(2) when you replace buses with trains on a primary, core route, ridership goes UP.
I don’t think you can use Yonah’s data to advocate for feeder branch-line rail routes (we don’t have many of those, do we? Austin, TX?).
But his data makes it VERY clear that you should be using rail for the primary, core routes. Which we knew already, of course.
Because of capacity limitations and service Seattle can’t wait to open the Light Rail from downtown to U. of Washngton, which is currently a core bus route.
I’m thinking primarily of what I see here in Philadelphia, but I think there is some room to generalize.
The period you are studying (the early 2000s) saw the first population growth city-wide in Philadelphia in decades. That growth has been primarily concentrated in the core urban neighborhoods, especially those arrayed along our heavy/light rail networks: Fishtown and Northern Liberties along the El, South Philadelphia along the subway, West Philadelphia neighborhoods served by the trolleys. There are exceptions (parts of South Philly and near North Philly only served by bus) but the relationship is pretty clear.
I’m not going to try to measure the causality here — Are new urban residents choosing these hoods /because of/ the rail, or are they choosing dense, mixed-use neighborhoods where rail transit is part of the overall urban package they’re seeking? It will be interesting to watch the next decade and see where the population growth flows – Along the heavy rail lines into less desirable neighborhoods, or into the areas between the spokes with (robust, but not quite equal to rail) bus service.
BRT is mentioned in the opening paragraph, but the post is not about Bus Rapid Transit at all. So, what can you conclude? Maybe that dedicated transit lanes / right of ways matter? (Assuming that street cars in traffic are a small percentage of all rail traffic) You can’t draw conclusions about rapid transit on rail from streetcars stuck in traffic, nor about Bus Rapid Transit from buses stuck in traffic.
Yes, this is a good question. I don’t have any evidence on ridership changes resulting from BRT in part because other than Cleveland’s line and L.A.’s Orange Line, it’s difficult to say that there is BRT in the U.S. Nonetheless, I did not include streetcars with the exception of San Francisco, Philadelphia and Boston, which operate semi-streetcar/semi-light rail operations.
The research on ridership effects of dedicated transit lanes is limited, unfortunately.
In the US, we only have dedicated lanes for rail. For buses… well, there are often dedicated lanes which peter out into general purpose lanes *right where the traffic starts*, which makes them kind of useless.
LA’s Silver Line BRT is a great example that peters out. Once it enters the edges of downtown LA, service slows to a crawl with the rest of traffic. Hopefully one day in the future, it will be converted to Light Rail.
That really wouldn’t be feasible due to the fact that most of the route runs on a route shared with freeway speed autos. And the downtown segment is pretty redundant with what will soon be two subway tunnels (one heavy, one light) and a streetcar route.
An easy solution would be to simply make the downtown street routes bus-only, and actually enforce them. Initially I’d say that’s very unlikely due to the fact that the streets are already somewhat narrow, but the projects to reduce lanes on Figueroa, Broadway, and Wilshire are encouraging signs.
The Silver Line drives home the dumb decision back in the 1980s, early 90s that over-focused on bus transit at the expense of sound corridors for rail transit.
The middle of a freeway is never a great place for rail, since there’s no TOD or walkability options.
Depends on the highway and how much money you want to spend. New Jersey’s second busiest bus station hovers over the Garden State Parkway.
Back in the 1980s when planning was underway for the 110 Freeway corridor the Los Angeles MTA, compelled by auto-centric politicians, took extra land beside the freeway and double double decked a portion of it for BRT and HOV lanes.
For the money that was spent, LRT could have been built in the same land on the west side of the 110 freeway all the way to San Pedro. It would have relieved more traffic congestion and improved air quality better than the ridiculous conversion of HOV lanes to HOT toll lanes today, which have recongested the other 10 lanes all over again.
Why the dramatic rise in Chicago rail ridership in 2005? I don’t think any new service opened that year.
a) rail is always built on the highest traffic corridors. this makes any such comparison suspect
b) even though a bus holds only a relatively small # of people, in most cases, bus service is less frequent on a line than rail. it would be very cost effective to double the freq of buses (v. building a rail line, for ex.) – many cities transit authorities imagine that every 30 minutes is adequate for buses, yet they run light rail on a 15 min interval.
c) Importantly, stigma is attached to riding a bus that doesn’t exist for rail. there is actually a positive cool factor with riding light rail, whether or not we like it, study it or even admit it.
The stigma is called rail bias.. In Houston, the growth of popularity of light rail has less to do with rail bias, then the improved running time of reserved street lanes for light rail and the notably faster acceleration of electric traction motors than bus internal combustion engines.
The Harris County Metropolitan Transit Authority, by buidling obstructions, makes it virtually impossible to drive on the rail tracks, which, coupled with video surveillance and active Metro Police enforcement, is very effective keeping motor vehicles off the line. In ten years, I have never seen an automobile drive on MetroRail tracks. Unlike New Orleans, even walking or cycling on the line can get you a ticket. The new Northline light rail is a vast improvement over the bus line it replaced. Thus, they avoid congestion and run at brisk pace through the otherwise most congested parts of town.
The predecessor bus line, the 15 Fulton, was a fairly heavy bus line. The gold standard of transit service is Sundays and holidays. On Sundays, the 15 ran every 20 minutes, which is fairly decent. During the week, the 15 Fulton ran every 15 minutes. The Northline Light rail is every 12 minutes, seven days a week.
The northern terminus of the 15 and the Northline light rail are the same, Fulton and Crosstimers.
The point is, the 15 Fulton took ½ hour to travel the same distance and the Northline light rail needs only 15 minutes.
It’s an old video, maybe the Darwin Award competitors have figured out that the streetcars aren’t an effective winning strategy,
what city was this video made in?
I believe it was Houston. Hopefully the drivers there have figured out what those arrows on the pavement mean by now.
Dude, you just defined “rail bias”. Those two attributes (plus the fact that trains ride much more smoothly than buses) are what results in “rail bias”; trains actually perform better than buses.
Now, there’s no doubt that the extra capital costs associated with rail is worthwhile only in limited situations, and if rail is adopted it must!!!!! have lane reservation and signal priority or separate right of way.
The number of riders & growth in ridership from bus vs. rail misses a very big thing relative to economics: in many cities light rail is designed to be used by more affluent people and is often used to connect areas where property values are rising (or is located in places where cities want to encourage rising property values).
As Doug mentioned, there is more of a stigma on using the bus and bus routes, in more cases, are used by people who have to use it (they don’t have a car sitting at home that they decide to not drive and instead take the light rail). I think there is less of a stigma against the bus in Portland, Oregon, but it still exists.
One of the really important things to consider when looking at rail vs. bus is whether the new service is put into areas where users who have to use public transit are being forced out by rising prices and make sure that adequate service (and better than adequate service) is being put into the areas where they are moving to.
I think to make this easier to read you might want to put “if so” between “rising prices and” and “make sure” in the third line, right? If that’s what you meant I agree.
That said, I hope you’re not implying “Don’t implement fixed guideway transit in a given area if it will result in ‘gentrification’ of that area” if such service improvements can’t be made because the people being forced out aren’t moving as a group to some other particular area that can receive increased service.
Because they probably won’t be doing that. So the implication is that the transit agency would need to improve service everywhere on the off-chance that somebody dispossessed from the newly gentrified area might move in. That would be a stultifying restriction.
I’d also be curious about the passengers per added cost instead of passengers per added service-hour, but for the two rail systems that I am somewhat familiar with (Caltrain, MBTA) there’s also the issue of more “upside potential” — where I live, if I want to take the bus in to Harvard and connections beyond, I walk to the main street, typically wait less than ten minutes, hop on a bus, and I’m moving. If I instead walk to the nearby square to hop on the commuter rail (unmatched speed to Porter Square and Government Center), I might wait an hour, or (I must consult the schedule, that is exactly the problem) perhaps two hours, and it turns out that mid-day the nearby stop gets no service (why? why-why-why? what’s the hurry mid-day, when trains are spaced two hours, that would have them skipping stops?)
So the bus is reliable, though not ultra-fast. The train is very desirable if its schedule happens to much mine, otherwise it is completely useless. Adding a train or two mid-day makes the chance of an acceptable schedule fit much higher. Simply not skipping stops mid-day wouldn’t cost much, and would effectively add a lot to the usefulness of the train.
Caltrain has many of the same issues, except that the adjacent bus transit is not nearly so good.
Seriously? I’ve never found the buses in Boston to be reliable enough to use at all. Often hours late for no particular reason (traffic “somewhere else” I suppose). The trains at least run on a schedule…
(Most) Boston buses work for me when I need them, which is pretty much all I ask. I often take them to the airport for business trips. They’d go faster if they weren’t stuck in traffic, of course, but the schedule that I know well does take traffic into account; you can see the schedule stretch out a bit during rush hour. The train runs on schedule (we’re within earshot of the track) but it is too sparse for me. Last time I used it was for an urgent passport renewal in downtown Boston, but it was useless for the return because of the long wait for a (scheduled) train.
It’s certainly possible that the trains are not trying to appeal to everyone, and instead are just on the lookout for the marginal-next-passenger. There are plenty of people with jobs that are well-scheduled and also match the train.
Well, I guess it’s good that the buses work for you. It’s probably a matter of which bus routes you’re dealing with. The one I remember giving up on was the #1.
I assume that at least part of the reason that bus has a less linear trend line correlating increased service hours to increased ridership is that bus service hours can be increased or decreased in several ways, while in most cities, rail service hours can be increased or decreased in only one way.
That is, in most cities, there are major trunk bus lines, local coverage routes, duplicative school bus service, and various other types of service. In most cities, there is only one type of rail line, since they all serve a single major transit corridor. I would expect that some bus routes are such that increased service hours would lead to huge increases in ridership, while other bus routes are such that increased service hours would lead to negligible increases in ridership, so the signal would appear “smeared out”. With rail systems, they all should produce about the same amount of increase in ridership per increase in service hour.
At any rate, what we can say from these data is that no (or few) cities increased only the service on bus routes that most reward increased service hours, if those routes are in fact as productive as rail.
I’m a bit curious about your Boston numbers. Boston hasn’t had any rapid transit expansions, really, in that time period (since 2000). There have, however, been several fare hikes. Bus fare was 60 cents and subway fare was 85 cents in 2000, now it is $1.50 and $2.00 if you use the CharlieCard.
Since 2000, the Blue Line has mostly finished its modernization program which allowed 6-car trains, which have been used 100% of the time for the past 5-6 years or so. The Green Line was rerouted into a new tunnel underneath North Station. I don’t think either of those can explain the ridership difference.
Expansions have been mostly on the commuter rail. Are you adding CR to HR and LR when counting? One problem is, the commuter rail has actually been losing ridership recently. And service was cut.
BTW, what did you count the Silver Line BRT as?
Bus ridership hit about 400,000 per weekday a few years back but it’s fallen since. The fare hikes may have played a role. It is possible that bus riders in this city are more elastic in response to fare hikes than rail users. There have also been some service cuts.
I have a data-free theory about the dip in commuter rail, which is that it scales (up or down) with congestion. I have a couple of friends who live “out there” not too far from the commuter rail, with yucky commutes all the way in to Kendall Square in Cambridge. What they report is that the train stations are inconvenient with unreliable parking, and (not a surprise to me) because there’s relatively few trains, it leads to an inflexible schedule.
They trade that off against the horribleness of their commute. In a down economy, traffic is down, congestion is down, so they drive instead of taking the train. Both friends drive hybrids so their fuel costs are not that large, and auto insurance tends not to scale that directly with miles, plus they already own the car.
Atlanta = even more budget cuts coupled with no state funding. They had to cut over 100 bus routes and raise fares to reduce the annual operations deficit.
Is there any way to control for level of service: 1) frequency, 2) speed, 3) distance of trip? I feel like most bus routes are just different than train routes, making this comparison somewhat skewed. What about comparing BRT to some forms of light rail?
Of course light rail raises ridership more than bus. People also prefer a Lexus to a Jetta, but that doesn’t say anything about whether someone should buy one car or another. Their prices differ.
One real question is: If you have $x to invest in one mode or another, which has the highest expected value in ridership?
Another question is: what does the distribution of costs and ridership look like? This is important, because the future is uncertain, and the life cycle of a light rail is measured in decades. No trader would accept the same interest rate on a 30-year mortgage that she would on a money-market fund.
Investing in bus offers the option value to change routes in response to new conditions and upgrade to technologies which might emerge over the 30-year life cycle of a light rail line. There are multiple startups, right now, looking at anti-bus bunching control systems and acceleration advice for drivers, and battery technology is only going to further erode the noise/fuel/pollution advantages (which are real) of light rail. We obviously are not going to get worse at providing bus service, but in each year over the next few decades there is a chance we might get better in some not-easily-imagined way. At the very least, because bus costs are cheap and spread over time, a bus investment preserves the option to invest in light rail later on if the advantage of light rail becomes clear enough–just like how 30-day T-note gives you the option to buy that mortgage down the road.
Finally, the distribution of costs for a tracked mode has a lot of variance and is skewed outward: there are fewer, smaller cost overruns in buses, because construction involves committing yourself to be at the mercy of contractors/weather/community challenges/bond markets/geology for extended periods.
Overall, bus is the smarter investment per dollar, and light rail largely prevails because it is hard to think about denominators and/or risk, bus riders lack political clout, outright fetishism, and the fact the feds slant subsidies toward capital-intensive choices.
Here I’ve only dealt with ridership, but the same goes for all the talk about streetcars/light rails development potential.There is no reason to waive away the question of how much things cost relative to their benefits simply because a choice is alleged to possess some other, even less certain and measurable (all of the development successes have involved lots of rezoning and/or subsidies and/or a region that was growing anyway), justification besides moving people around. If you could know how much development you’re getting, that would simply be something else to put in a numerator and compare between the two modes. And it’s not even clear why development should be traded off against serving riders in the first place. Is there some huge lack of boutique shops opening in our cities and a surplus of transportation options for people without cars?
Lewis makes some pretty good points. Bus flexibility can be a curse as much as a blessing, as routes (subject to public input from people with too much time on their hands) often get complicated over time, while rail is not impacted by the same pressures. Quality assurance for light rail is a lot better, whereas “BRT lite” has no definition whatsoever.
But the difference in cost is immense. There are places where rail makes more sense, and where bus makes more sense. I can think of approximately zero cases where rail investment is worth it in mixed-traffic with vehicle lanes.
In some places you get more per dollar from rail then you’d get from anything else, because of unique circumstances. In Austin, I-35 is already elevated over itself, Mopac is a parking lot, NIMBY opposition to wider highways is huge and opposition to taking lanes away from cars for buses is likely higher, and there was a lightly-used freight line available. So, capital metrorail.
In South Florida, they converted a rail line into a busway that they’re turning into a toll road. All for a cost that all-told is probably higher than what simply extending rail service over the old rail line would have been.