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Re: Good questions Max...
Author: BOB2
Date: 11-29-2019 - 17:26
Max,
Happy American Thanksgiving, makes me want to go out the Zurich Zee and poach one of those mean swans, and stuff it.... Meanwhile, these are good questions.
Many of the proposed bus lanes were on routes in and around downtown LA, for this analysis. Bus stops tended to be under 1/2 mile with high intensity single door boarding, and mostly pass riders during peak periods (more cash off peak, mostly far side stops, wi.th a couple of "super" stops mid block. These included segments of Wilshire (no effect), Hill, Flower/Figueroa, Grand, Spring Street, and IIRC a segment of Glendale Blvd,, in high bus usage high bus traffic corridors (20+ peak hour buses or more, except Glendale)
This was back before we did transit vehicle signal pre-emption/prioritization. Which has been shown to "average" speeds by up to 3 to 4 percent on the route where is has been used. However, most of the effect of pre-emption/prioritization is to keep the buses on schedule in highly variable traffic congestion conditions.
We then had one reverse exclusive bus lane northbound on Spring Street (which was one way southbound one way, with buses operating in mixed flow lanes southbound)from 8th Street to the 101 Freeway, with a single lane between 8th and 1st Street, and a full double bus lane, from 1st Street (LA City Hall with 4 "mega stops" and where about 25 local and El Monte busway buses, turn north from 1st Street.
We disaggregated the impacts of boarding and alighting delay, signal wait times, pulling into and out of the traffic flow on weekday (Tuesdays and Wednesdays IIRC?) during peak periods, we then ran the same routes on weekend mornings (least volume periods) to simulate the impact of an exclusive lane, and then added the peak loading times, to assess the impact of a "free flow" traffic lane. The results showed NO difference in travel times from uncongested travel times (the purported benefit of an "exclusive" dedicated bus lane).
In fact, since we also tested the exclusive lane we already had, and found that between 8th Street and 1st Street, the reverse flow exclusive single lane busway had a longer travel time than the buses going southbound with the on Spring over the same segment, with one of the highest bus accidents rates for MTA for such a short segment of bus route. The double segment from 1st Street to the 101 is a double lane, to avoid bus conflicts while loading at the City Hall "mega" stops, and had fine performance. The segment on Spring Street from 8th Street to 1st Street was subsequently removed.
One problem I've seen with the very few studies which "claim" benefits from arterial bus lanes, also involve stop relocation, longer distances between stops, fewer total stops per mile, multi-door loading, and signal pre-emption, and all failed to disaggregate the multivariate impacts of those discreet components to show benefits of the lanes.
And, none of these studies analyzed impacts touting the purported benefits of the kind "take a lane" exclusive bus lanes currently being proposed on already congestion "saturated" "suburban" land use corridors, some which would only be running 6-12 BRT buses using the lanes each direction per hour, on traffic congestion and mixed flow congestion delay, intersection cueing and delay, or increased emissions from lower average arterial speeds, resulting in greater fuel use, and greater CO2 emissions. Which is necessary to do actual "cost benefit" analysis of these proposals.
There are circumstances and bus volumes where exclusive lanes have shown some benefits, but not under most of the circumstances at most of the routes now being proposed for LA. The double lanes in front of City Hall on Spring Street "works", and doe reduce bus transit times (partially because the double bus lane, allows for multi-stop boarding, without blocking and delaying the other buses.
Longer stop spacing, better bus stop design, multi door boarding, improved fare media, and bus traffic signal pre-emption/prioritization all can reduced bus travel times and improve average operating speeds, and have good data to support the benefits.
Of course, since the evidence for "exclusive" arterial bus lane benefits is weak, and since I came from a generation that still had to justify these kind of things on math, and have done such work, I'm just a wee bit skeptical. So now, I'm officially considered a dinosaur, for my skepticism, by those who now "advocate" for these things, based on the "new urbanist" math free "faith based" planning doctrines being preached these days.
Happy American Thanksgiving, makes me want to go out the Zurich Zee and poach one of those mean swans, and stuff it.... Meanwhile, these are good questions.
Many of the proposed bus lanes were on routes in and around downtown LA, for this analysis. Bus stops tended to be under 1/2 mile with high intensity single door boarding, and mostly pass riders during peak periods (more cash off peak, mostly far side stops, wi.th a couple of "super" stops mid block. These included segments of Wilshire (no effect), Hill, Flower/Figueroa, Grand, Spring Street, and IIRC a segment of Glendale Blvd,, in high bus usage high bus traffic corridors (20+ peak hour buses or more, except Glendale)
This was back before we did transit vehicle signal pre-emption/prioritization. Which has been shown to "average" speeds by up to 3 to 4 percent on the route where is has been used. However, most of the effect of pre-emption/prioritization is to keep the buses on schedule in highly variable traffic congestion conditions.
We then had one reverse exclusive bus lane northbound on Spring Street (which was one way southbound one way, with buses operating in mixed flow lanes southbound)from 8th Street to the 101 Freeway, with a single lane between 8th and 1st Street, and a full double bus lane, from 1st Street (LA City Hall with 4 "mega stops" and where about 25 local and El Monte busway buses, turn north from 1st Street.
We disaggregated the impacts of boarding and alighting delay, signal wait times, pulling into and out of the traffic flow on weekday (Tuesdays and Wednesdays IIRC?) during peak periods, we then ran the same routes on weekend mornings (least volume periods) to simulate the impact of an exclusive lane, and then added the peak loading times, to assess the impact of a "free flow" traffic lane. The results showed NO difference in travel times from uncongested travel times (the purported benefit of an "exclusive" dedicated bus lane).
In fact, since we also tested the exclusive lane we already had, and found that between 8th Street and 1st Street, the reverse flow exclusive single lane busway had a longer travel time than the buses going southbound with the on Spring over the same segment, with one of the highest bus accidents rates for MTA for such a short segment of bus route. The double segment from 1st Street to the 101 is a double lane, to avoid bus conflicts while loading at the City Hall "mega" stops, and had fine performance. The segment on Spring Street from 8th Street to 1st Street was subsequently removed.
One problem I've seen with the very few studies which "claim" benefits from arterial bus lanes, also involve stop relocation, longer distances between stops, fewer total stops per mile, multi-door loading, and signal pre-emption, and all failed to disaggregate the multivariate impacts of those discreet components to show benefits of the lanes.
And, none of these studies analyzed impacts touting the purported benefits of the kind "take a lane" exclusive bus lanes currently being proposed on already congestion "saturated" "suburban" land use corridors, some which would only be running 6-12 BRT buses using the lanes each direction per hour, on traffic congestion and mixed flow congestion delay, intersection cueing and delay, or increased emissions from lower average arterial speeds, resulting in greater fuel use, and greater CO2 emissions. Which is necessary to do actual "cost benefit" analysis of these proposals.
There are circumstances and bus volumes where exclusive lanes have shown some benefits, but not under most of the circumstances at most of the routes now being proposed for LA. The double lanes in front of City Hall on Spring Street "works", and doe reduce bus transit times (partially because the double bus lane, allows for multi-stop boarding, without blocking and delaying the other buses.
Longer stop spacing, better bus stop design, multi door boarding, improved fare media, and bus traffic signal pre-emption/prioritization all can reduced bus travel times and improve average operating speeds, and have good data to support the benefits.
Of course, since the evidence for "exclusive" arterial bus lane benefits is weak, and since I came from a generation that still had to justify these kind of things on math, and have done such work, I'm just a wee bit skeptical. So now, I'm officially considered a dinosaur, for my skepticism, by those who now "advocate" for these things, based on the "new urbanist" math free "faith based" planning doctrines being preached these days.
