Bus Only Lanes Will Create Increased Congestion As Driving Is Increasing

Cost Commentary: Robert Poole, Jr., Director of Transportation Policy, presents two related comments in the recent issue of the Reason Foundation’s “Surface Transportation Innovations” current issue which are particularly pertinent to Austin current transportation policy direction.

The first comment is a recognition that current transportation reports, Including the Federal Highway Administration’s (FHA) “Traffic Volume Trends” indicate vehicle roadway traffic miles traveled is now above that recorded prior to the recent recession and the trend’s current growth rate is about the same as the average rate from 1991 and prior to the recession. Below is the chart from the FHA report:

Figure 1 – Moving 12-Month Total on All U.S. Highways

This chart contradicts the many articles and views expressed over the past few years that the recession driving trend indicated a major change in peoples choices and habits regarding transportation. Numerous people expressed a view that millennials’ preferences changed from previous generations and were a major factor in changing driving habits. As in numerous previous situations, short term transportation trend impacts have not been based on changes in fundamental human preferences for the convenience, opportunity and quality of life provided by private transportation.

The short piece below by Robert Poole, Jr. from Reason’s Surface Transportation Innovations describes his experienced view that ‘bus only lanes’ often result in major increased congestion. He mentions Austin in this regard. This congestion increase will be worsened as U.S., Texas and Austin region driving is now greater than prior to the recession and has regained its pre-recession growth trend. Poole states there are better alternatives than ‘bus only lanes’ to provide improved transportation for the overall community.

Poole’s observations are very relevant as Austin is now considering ‘bus only lane’ implementations on key thoroughfares which would reduce private vehicle lanes, resulting in major congestion bottlenecks and degrading overall transportaion.

When Are Exclusive Bus Lanes Warranted? by Robert Poole, Jr.

A small but growing number of transportation researchers (including me) have argued for years that bus rapid transit (BRT) is generally far more cost-effective than light rail, as well as being a lot more flexible due to not being confined to a single guideway. But now that the BRT idea is gaining more adherents, ill-considered projects threaten to make arterial traffic congestion far worse. The culprit is conversion of existing general-purpose lanes to bus-only lanes.

Examples are proliferating. The draft 2040 Regional Transportation Plan for the Austin metro area calls for converting a number of major downtown streets to bus-only—including Riverside Drive, South Congress, North Lamar, Guadalupe, and several others. A major study recently completed in Boston proposed “gold standard” BRT service on exclusive lanes on five major corridors where bus ridership is already high and travel times are slow. The Los Angeles City Council last month approved a 20-year transportation plan that would convert hundreds of miles of traffic lanes to bike lanes and bus-only lanes. And the Metropolitan Planning Organization for Miami-Dade County in February approved a project development study of converting one lane each way to bus-only use on three major arterial corridors: NW 27th Avenue, Flagler Street, and Kendall Drive. Pretty renderings show articulated buses operating in 11 ft. curbside lanes, alongside widened 15 ft. sidewalks, with only two 11 ft. general purpose lanes each way.

What is not being discussed very much (or at all) in these cases is the impact on traffic congestion of converting general-purpose lanes to bus-only use—especially during peak periods when most major arterials are already seriously congested in these metro areas, operating at Levels of Service E or F. Reports that assess such impacts do exist, including a 1975 report from the National Cooperative Highway Research Program, “Bus Use of Highways: Planning and Design Guidelines” (NCHRP 155). That report recommends that the minimum one-way peak hour bus volume needed to justify a curb bus lane is 50 to 80 buses/hour, carrying 2,000 to 3,200 passengers.

A recent report by smart growth advocate Todd Litman cites that report, along with several others proposing significantly lower thresholds. Litman argues for using a whole array of factors, not just traffic/congestion impacts—including social equity objectives and ensuring that “bus passengers receive their fair share of public road space.” (“When Are Bus Lanes Warranted?” Victoria Transport Policy Institute, August 2015)

Several years ago my traffic engineer friend and colleague Chris Swenson worked with me on a major study on improving mobility in Southeast Florida. Our report recommended a large-scale expansion of both “BRT Lite” service in mixed traffic on arterials and longer-distance region-wide express bus service operating on major arterials and on the envisioned network of freeway managed lanes (which is now being developed). We looked at how to handle the express buses on major arterials, and found that bus-only lanes would have serious negative effects on congestion. On a typical six-lane major arterial in Southeast Florida, with traffic signals at about one-mile intervals, our quantitative analysis found that converting one lane each way to bus-only would increase congestion from LOS E to LOS F unless bus ridership increased to 34% of all people using the corridor during peak periods. That high a transit mode share was so far beyond anything contemplated in long-range transportation plans that we rejected it as fantasy.

Instead of bus-only lanes, we modeled the addition of electronically tolled underpasses at key signalized intersections, in which motorists would have the option of paying a modest toll of 15 to 35 cents (depending on time of day) to bypass what is often a 3-minute traffic signal cycle time. Our modeling showed that an arterial reconfigured in this manner would have greater person throughput than the six-lane arterial with two bus-only lanes at all conceivable percentages of transit mode share. We dubbed the concept “managed arterials,” and described it in TRB paper 12-1248, which was later published in Transportation Research Record 2297. Revamping major arterials as managed arterials would be far wiser than converting some of their lanes to bus-only use.

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