(10 am. – promoted by ek hornbeck)
Burning the Midnight Oil for Living Energy Independence
Yonah Freemark at his site The Transport Politic discusses Chicago “BRT” proposals. “BRT” is the transit professional and transit blogger three letter abbreviation for “Bus Rapid Transit.
See, sometimes spelling out the abbreviation doesn’t do that much good on its own. The idea of “Bus Rapid Transit” is to implement a range of features we normally associate with rail based “rapid transit” for specific bus routes, which then can offer some of the benefits of rapid transit that is not normally available to bus riders.
The BRT category is a fuzzy one, ranging from slapping a paint job on the buses and installing bus stops with better seating and “next bus” indicators to dedicated lanes, signal priority, and purchase of tickets at the stop. What the Chicago Transit Authority has proposed is three routes on the “BRT-lite” side, but as Yonah covers, the business leaders on the Metropolitan Planning Council have proposed a much more expansive system (see map).
While the My-Mode-Uber-Alles types will line up for or against the BRT proposal based on whether buses are “their” mode or “a rival mode”, in the real world there is no fundamental conflict between BRT and streetcars. Indeed, it makes much more sense for streetcars to share a lane with BRT than for streetcars to run mixed in traffic with automobiles.
Levels of BRT
The ordinary city bus is the foundation level service for most public transport systems around the country. And the “way a citybus works” is often taken for granted by the residents of a city or set of towns served by a city bus system.
But back in the 1980’s, local leaders in Curitiba, Brazil who were looking at how they could improve transport in their city, began a process of widespread consultation on transport improvements and the pursuit of hundreds of small improvements rather than a few “big projects”, and the system that they developed broke the mold for city buses mixed in traffic and inching slowly down congested boulevards.
The Curitiba system is built with three tiers of service. Neighborhood minibuses connect neighborhoods to local destinations and citywide bus routes. Conventional buses run circular routes around the city and inter-district routes. And Bus Rapid Transit routes run into one of five main arteries through the downtown, on lanes dedicated to BRT, serving “stations” where you pay to enter the pre-paid passenger area … so that when the bus arrives, you just step onto the bus, like subway passengers waiting for a subway.
Now, of course the proposed Chicago system does not involve handing over whole streets to the BRT, but while the Chicago Transit Authority runs buses mixed with auto traffic, the MTC proposal involves buses res running in their own lanes on a “complete street” with pedestrians, cyclists, motorists and BRT all having their own right of way.
Mixed Traffic Streetcars
The problems faced by Streetcars running mixed in traffic are much the same as the problems of buses running mixed in traffic. Just like city buses running in many downtown areas, they often run at a walking pace ~ though of course for longer distances than it is comfortable for many people to walk in extreme weather or when carrying bulky or heavy packages.
They still have some perceived advantages over buses, including what is normally a far better known route ~ and a route that is not subject to an unexpected diversion because you misread a route number. Modern streetcars are normally an articulated modular design with substantially more capacity than an ordinary bus ~ and running on rails, offer a steadier ride than an articulated bus. And developers like them because a streetcar line is perceived as being more permanent than a bus route.
But once you have bus “stations” connected to dedicated BRT lanes offering the buses in the lanes signal priority at intersection … won’t that be perceived as a permanent route?
Well, I’ll give you one way you can make it look even more like a permanent route: put streetcar tracks in it.
Streetcars will gain the same speed benefits from having a dedicated transit lane as the BRT buses. The level boarding height of ultra low floor buses and ultra low floor streetcars is the same, so the same stations can work for both. They both gain the same benefit from the signal priority at intersection. And any modern public transport system should have buses and streetcars on an integrated ticketing system.
Now, if we think of streetcars as some distinct means of transport, as we tend to do in the US, you might wonder what streetcars add to the transit lane above some vague sex appeal factor. But thinking like a European where a “tram” is still a tram when it runs in its own lane on the street or when it runs on its own light rail right of way, and is a “tram-train” when it is also able to run onto the heavy rail network …
… well, that’s what the streetcar offers to bring to the transit lane. Direct, no transfer, connection out into a dedicated light rail or heavy rail corridor. With the transit speed picking up when it hits the dedicated rail corridor, this is often referred to as a “Rapid Streetcar” system.
And the BRT gives direct, no transfer, connection to the main road arteries of suburbs and towns that the outer ends of the routes can serve before merging onto the BRT corridor.
And, indeed, the shared lane offers a single-transfer trip from anywhere the streetcar
Wait a Minute … there’s a little problem here …
Once the option of a combined BRT / streetcar transit lane is brought into the picture … the problem to be overcome snaps into focus.
Do we build the rails in from the beginning, even though we do not know which of the sections of which BRT lanes will actually receive streetcar services? Or do we shut down the BRT system once we have got it up and running, to build the rails in at that point?
Well, if the proposal is to build a streetcar line, and the mixed streetcar/BRT design is being used to build support for excluding automobile traffic from the line, then of course you build the tracks in from the beginning. The modifications required to ensure that the lane works as a BRT lane as well as a streetcar lane are fairly modest, after all.
But what if its a BRT lane at the outset, and the streetcar is to be added later? That is a scenario requiring a valuable resource that seems to be in relatively short supply: intelligent forward planning.
Consider the design pattern above for a street segment that happens to have BRT stations on it. The design envelope certainly permits a shared BRT/streetcar lane … but greater leeway between the station and the intersection may be better for a streetcar lane. The capital cost of adjusting that at the BRT design stage would be minor, while the capital cost for making that adjustment after the BRT station is built would range from modest for some modular designs to substantial for others.
The trickiest part of adding a streetcar route after the BRT is running is, of course, laying the track. It would pay substantial dividends if the system for laying the track into the BRT lane was already worked out before the BRT lane was built.
On the one hand, a new surface with the track built into it may be laid on top of the existing lane. This is likely the least disruptive solution as far as diverting the buses off of a BRT street segment during construction. However, any median, lane separations, and in particular any station along a segment should be designed from the outset with the height of the new surface in mind.
On the other hand, laying the streetcar track into the street at the original lane height avoids the increase in height of the combined lane, but requires pavement to be torn up and then replaced.
A hybrid approach might lay segments of track into the street for intersections and station segments, with new surface laid on the top of the BRT lane in the segments in between.
But however the lane is to be shared, you can’t run the BRT down that street, while the streetcar segment is in use … can you?
Oh, nonsense, of course you can. Sure you have to close the street to car traffic, but in closing the street to car traffic, you have one car lane and one parking lane, with a cycle lane in between them. Run the BRT routes down the automobile traffic lane, place the temporary BRT station on the normal cycle lane and part of the parking lane, and shift the cycle lane to the curb. The cyclists will have to yield to pedestrians crossing from the sidewalk to the BRT station, but they have to do that anyway, and its a small price to pay for use of the complete street.
While you have to close the intersection to crossing traffic when installing the track through that intersection, that doesn’t affect the BRT services running along that route.
Setting out and solving the design challenge in advance of establishment of the BRT corridors will reduce the disruption and capital cost of adding streetcar segments down the track. But if you do it right, the major disruption during streetcar track installation will be on cars, and the BRT services will proceed in temporary dedicated lanes with very little disruption.
Electrification
One of the substantial benefits of a dedicated BRT corridor is the opportunity to electrify the corridor for use by electric trolley buses.
Trolleybuses have their own distinct challenges. One long time problem is that in running along the ordinary right of way, they more frequently encounter obstacles than trains running in dedicated rail corridors do. Another is that the overhead power supply is more complex than electric rail: without steel wheels on steel rails to act as a ground conductor, they must be provided with overhead power and return lines. When including the through lines and branch lines, the overhead lines at intersections can turn into quite a mess of wires, especially where two trolleybus route intersect.
When fitted with battery support that recharges off of the overhead electric power, modern trolleybuses can avoid these problems, by running out from under the wires to get around obstacles, and by running through intersections on their own power. Indeed, since the power efficiency of dynamic braking is primarily gained at stops, and most power is required when accelerating out of stops, it would be feasible to design a BRT trolleybus system with the power lines focused primarily on the blocks with BRT stations.
Electric streetcars once relied on a single trolley pole to connect to power supply, and this approach is directly compatible with trolleybus power supply, as long as the system reliably connects the streetcar trolleypole to the power line. However, given risks of dewirement, modern streetcars normally work with a bow collector or pantograph, which would normally short out the double power and ground return lines of a trolleybus power supply.
Still, sharing the power infrastructure between trolley buses and streetcars is a quite appealing prospect. One approach would be to outfit a streetcar with both system, relying on a retractable, reversible trolleypole when in the shared BRT corridor, and a bow collector when operating in its dedicated rail corridor.
For this fictitious rapid streetcar to on a “station segment wired” BRT corridor, it would require battery power as well. However, that opens the door to other capital savings, since rail corridor electrification sometimes run into substantial costs in capital reconstruction, because there is no room to get the train through with space above to spare for the power supply. An option to run off of battery power for a segment could save substantial capital costs when re-using an existing rail corridor that was not originally designed to be electrified.
Of course, the opportunity to run trolleybuses does not imply that all of the BRT buses will be trolleybuses. If multiple routes are collected into a common BRT corridor, it may make sense to electrify some of the routes but not others, and to electrify incrementally, a route at a time.
In addition to just running fueled buses under the wires, electrification of the the BRT corridor opens up the opportunity for “pluggable” hybdrid electric diesel buses where their “plug” is a trolleypole. With a high efficiency, fixed speed diesel generator that only runs when needed to recharge the battery, and a short section of trolleywire at the layover at the outer end of their route, the “pluggable” hybrid electric bus can ensure that the section requiring the diesel engine to kick on is as short as possible, minimizing the exposure of the bus operator to the frequent and severe oil price shocks that we will be experiencing in the coming two decades.
Streetcars and BRT: Best Friends Forever?
What if … what if the demand for the Streetcar and BRT services generates a conflict? After all, the whole idea here of sharing infrastructure to reduce capital costs assumes that the dedicated transit lane has sufficient capacity.
What if it doesn’t?
The answer then is the same answer that Curitiba arrived at, made possible for the same reason that it was possible in Curitiba: kick the cars off the street, and take over their lane for the BRT.
Efficient modern BRT services carry far more passengers than a lane of automobile traffic. Streetcars carry still more. If the shared lane is at capacity, it will be carrying 80% of the large vehicle passenger traffic on that street. Indeed, the best thing that the motorists can do in that situation is to give up those lanes.
Motorists today might not understand it that way. However, there’s no need to have the argument today. The argument, if it becomes necessary, is only needed after there is so much combined BRT and streetcar traffic on the corridor that more capacity is needed. And in that setting, the case on the benefits of the BRT and Rapid Streetcar system in reducing traffic and parking congestion would not be a matter of projecting into the future. It would be a simple matter of observing the present day.
And beyond that, the percentage of motorists requiring convincing would be lower … because that world in which the services press against the capacity of the combined BRT and Rapid Streetcar corridors is one with a smaller share of passengers arriving in automobiles.
Which is, after all, why Curitiba was in a position to do what US efforts to imitate them have done, in taking over whole city streets and banning the car in order to provide the lane capacity in downtown. With a much larger share of its population on the existing city buses, it had a smaller proportion of the car passengers to convince to gain a working consensus.
Midnight Oil ~ A River Runs Red
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