BRT capacity to meet future demand.
I have expressed my concern that the efforts of the Town of Chevy Chase to promote Bus Rapid Transit on Jones Bridge Road (BRT on JBR) could have unintended consequences, in Will the BRT campaign backfire?. I closed that post with a promise to address the BRT vs. LRT issue in a future post.
Those of you who are interested in this BRT vs. LRT issue have had plenty of newspaper articles and blogs to follow. The discussion has been driven into hyperdrive by the Washington Post article Md Busway Promoted as Solution to Gridlock and by a Montgomery Gazette article Council member’s rapid bus system on transit table. If that is not enough, a guest blog by Delegate Al Carr in Just Up the Pike supporting BRT on JBR triggered a robust online discussion as other blogs quickly joined the discussion. A few of the most significant discussions are at Rebuilding Place in an Urban Space, Greater greater Washington, and Maryland Politics Watch.
I don’t want to rehash the whole BRT vs. LRT debate here. Nonetheless, there are some aspects of the BRT on JBR design option that are important to whether BRT on JBR is the best Purple Line option as the Town of Chevy Chase claims. I will describe discussions that occurred recently between M-NCPPC staff and MTA staff at the Dec. 8 Planning Board work session.
Demand vs. Capacity:
The issue of BRT capacity was discussed at the Dec. 8 Planning Board work session. The work session staff memorandum presented projected peak ridership estimates that showed the BRT will be at or near its full design operating capacity by 2030. In the most important Purple Line segment (i.e. the one nearest my home) at Silver Spring to 16th Street, the projected “Peak directional line load” is 1652 passengers/hour for the Medium Investment BRT, and 1858 passengers/hour for the High Investment BRT. MTA staff present at the meeting indicated peak load in east Silver Spring will be almost as high. MTA estimates the design BRT capacity to be 2100 passengers/hour. Since the capacity (2100) slightly exceeds the highest estimated demand (1858), it looks like we are “good to go”.
But the M-NCPPC staff has some reservations about the MTA capacity estimate that they describe in their staff memo. They have found what they consider to be more realistic studies on BRT capacity that indicate the Purple Line BRT design peak line load capacity would be 1800, not the 2100 MTA has assumed. The extended discussion between MTA staff and M-NCPPC staff at the meeting appeared to support the M-NCPPC staff concerns. MTA assumes 140 people per BRT vehicle with 15 vehicles in each direction per hour for the Purple Line estimate, but 120 people per BRT vehicle may be more realistic. MTA assumes it can inject extra “jumper” vehicles into to the Purple Line system at the peak hour to meet the demand. But there was agreement among the M-NCPPC and MTA staff during the discussion that the ability to introduce more vehicles is greatly compromised by the BRT Purple Line design that has the buses running on busy streets in traffic at the ends of this peak load section, in both downtown Bethesda and east Silver Spring. In short, you can’t just put a lot more buses out there if the buses do not have their own dedicated lane, because the street traffic will screw the bus intervals up and too many buses will screw up the street traffic if they have signal priority. The discussion can be seen on video, from the Planning Board agenda webpage. The discussion on Purple Line capacity was the first major issue taken up.
The give and take in the discussion about whether or not BRT will be over capacity in 2030 distracts us from the real capacity problem. During the Planning Board discussion Dr. Glen Orlin, Mont. Co. Council Staff Director, pointed out what I think is the elephant in the room when we talk about Purple Line capacity. The Purple Line AA/DEIS is required to measure ridership against year 2030 projections for consideration for funding by the federal government. But the Purple Line will only be 15 years old by 2030 under the most optimistic construction schedule. What will the demand be in 2050, at 35 years of age?? Does anyone doubt the demand will be much higher? What if the cost of gas goes up again soon, to even higher levels than seen recently, and transit demand grows faster than the models predict – in which case we will not even make it to 2030 before capacity is exceeded by demand?
It is nuts to consider building a legacy transit system with BRT if it is going to be at or near full capacity within 15 years of construction when it cannot be easily modified for higher capacity. In contrast the M-NCPPC staff memorandum shows the LRT Purple Line has the capacity to meet the 2030 demand. More important, both M-NCPPC staff and MTA staff appeared to agree during the discussion that LRT can be expanded much more easily than can BRT to carry the much higher demand likely to come beyond 2030.
I know this discussion doesn’t relate to the trail directly, but it does relate to whether the BRT part of BRT on JBR is a good idea. In the next post on this issue I will turn to another issue covered in the Dec. 8 Planning Board work session that is more closely related to the Trail, how the BRT on JBR alignment option measures up against BRT alignments on the Georgetown Branch Trail.