Tuesday, March 27, 2007

Enforcing HOV, rail vs. edgeless cities, arterial underpasses, intermittent bus lanes, and H2 cars

I've been getting an email newsletter from Bob Poole at the Reason Foundation called "Surface Transportation Innovations" for some time. It's always high-quality, usually with several short, intriguing articles on, well, transportation innovations. They come out monthly, and I think I'm going to start covering them pretty regularly in this blog, since transportation is such a critical issue for Houston. Today we'll cover the February issue.
A New Approach to Enforcing HOV Occupancy
...Recall that the original idea of HOV lanes was to reward those who reduced the number of peak-period vehicles by carpooling. So as part of the shift from HOV to HOT, we could refocus the carpools-go-free aspect on commuter trip reduction by allowing only employer-sponsored carpools to use HOT lanes at no charge (or a reduced rate). The local ride-sharing agency could issue transponders to participating employers, who would issue them only to carpool groups which they (the employers) certified as legitimate, regular carpools. Those transponder ID numbers would be identified in the billing/enforcement software as authorized free or discount users.

Hence, on-road enforcement would be entirely electronic: there is either a valid transponder or there isn't, and in the latter case, there is a toll violation. The ride-share agency would need to periodically audit participating employers to be sure the authorized carpools were still active. Whenever a carpool was found to be defunct, the employer would retrieve the transponder, and the tolling software would delete that ID number from the authorized carpool list.

Given that some studies have found that between one-third and two-thirds of all current carpools are actually fam-pools, and that many HOV lanes also have violation rates between 10 and 20%, this redefinition of carpools would dramatically reduce the number of vehicles using the HOT lane without paying. So not only would enforcement costs drop significantly, but net toll revenue would also increase.

I have long argued that vanpools and buses (super-high-occupancy vehicles) should be the only vehicles authorized to use HOT lanes at no charge. But in places where the carpool aspect is considered very important, refocusing the HOV privilege on employer-sponsored carpools would be a major step toward more cost-effective transportation.
The second story is on the problem of rail transit in the new "edgeless cities" of dispersed jobs.
...The new metropolis "is mostly low-to-mid density, automobile dependent, and dispersed."

The new analysis finds that edgeless cities account for almost 40% of the total office space in those areas, while their downtowns averaged 33% and their edge cities just 14%. The balance fell into "urban envelopes" (5.2%), "corridors" (3.8%), and "secondary downtowns" (1.2%). You can download the report at www.mi.vt.edu/uploads/Edgeless%20Cities.pdf (Houston details p.27)

The most fascinating aspect of the report is not the averages but the differences among these large urban areas. Atlanta and Miami have the smallest fraction of office space downtown, at just 6.7% and 8.7% respectively. The edge-city champions are Houston (33.3% edge-city space), Detroit (27.1%), and Washington, DC (23.3%). And the metro areas with the largest fraction of their office space in edgeless cities are Miami (72.1%), Detroit (54.1%), Philadelphia (54.3%), and Denver (50.8%).

The final sections of the report discuss policy implications. Citing a 1977 study by Pushkarev and Zupan which found that 8,000 people per square mile was the minimum threshold for rail transit (Houston is mostly around 3,000), Lang and colleagues parsed their data to determine the amount of edgeless city office space located in neighborhoods with at least that much density. Atlanta had zero, and another seven had only single-digit percentages (inc. Houston at 6.5%). The most promising were Los Angeles (36.7%), San Francisco (27.8%), and Miami (13.8%).
This reinforces my assertion that commuter rail is not a good fit for Houston, but a network of high-speed lanes with express bus/van service to all the different job centers is.

His third story is on underpasses at arterial intersections, which are often considered too expensive to be practical, but would be very helpful in many parts of Houston.
....a lower-cost version of the idea: the low clearance underpass. Instead of building it to provide the standard 16-foot clearance height, they proposed just eight feet. That permits all current cars, SUVs, and vans to use it, with a one-foot margin of safety. Trucks and buses (10% of the total, in their study) would have to use surface-level through lanes.

The costs of the low-clearance underpass would be lower, because of less excavation and material, a shorter length (39% less, with the same 5% grade), and less need for additional right of way acquisition. Using data from the Hawaii DOT, they estimated the construction cost to be 38% less—not counting any savings from reduced right of way.

...When they estimated the value of the time savings over the course of a year, they estimate that the underpasses would pay for themselves over a two to five year period.

Taking a closer look at their assumptions in this calculation, I find it to be very, very conservative. Personal travel time is valued at just $7.80/hour, truck traffic at $19/hour, and savings were counted for only 250 days/year and for only two peak hours per day. With more realistic assumptions, the break-even period would be even less than the 2-5 years they estimated.
Next, he has a story on "intermittent bus lanes", that give bus-rapid transit the speed benefits of their own dedicated lane, without actually giving them a dedicated lane and its loss of right-of-way. This could be a great idea for the planned BRT lines in Houston, especially through Uptown.
The basic idea is that the lane functions as a regular traffic lane when a bus is not present. As a bus approaches a section of the lane (a block or two), the lane's status changes and usage is limited to bus-only. Obviously, making this work depends on technology for monitoring bus locations in real-time and for alerting drivers (via lane-lighting and variable message signs) about the changing lane status.

The demonstration project took place on a half-mile avenue near the main university area in Lisbon, at the edge of the central business district. It ran for six months, beginning in September 2005. During peak hours, bus speeds were 45-60% higher than without the IBL, with a daily average speed increase of 15-25%. Surveys of motorists showed good acceptance; the IBL was perceived as fair sharing of limited roadway space. Viegas told us they are about to launch a second demonstration, in a more complex location, this time including photo enforcement.

... the IBL looks like a way to provide many of the benefits of an exclusive bus lane without the huge negative impacts on traffic of totally removing that lane from general service.
The final story that caught my eye is the hydrogen BMW.
Limitations of Hydrogen BMW. Like many of you, I'd love to see the widespread use of emission-free motor vehicles. So I was intrigued by BMW's announcement last fall of a hydrogen-powered luxury sedan. Then I read the fine print. First, the H2 fuel tank weighs 369 pounds and takes up half the space in the trunk. And because the liquefied H2 slowly turns into a gas, a half-full tank will completely boil off in nine days. Because the car can only go 125 miles on its hydrogen fuel supply, it also has a gasoline engine and gas tank, good for another 300 miles. Clearly, this project is not ready for prime time. (Source: MIT's Technology Review, January/February 2007)
But here's an alternative version that could yield major greenhouse gas reductions and might be pretty scary to oil companies: an H2 tank a third of that size that gives you about 40 miles (a typical daily usage), and fills up each night in the garage by pulling H2 off of the home's gas line, or even the water line - using cheap nighttime electricity. The normal gas tank gives you extra range when you need it, and since the combustion engine can burn either clean-H2 or gas, there's no need for expensive fuel cells, batteries, or electric motors. If it could be produced affordably, and the H2 cost-per-mile beat gasoline (I've heard raw electricity cost-equivalents of around $0.50/gallon for plug-in cars, but there would be some additional energy efficiency losses with the H2 make-and-burn), you'd have a real winner.


At 9:24 PM, March 28, 2007, Anonymous Anonymous said...

I believe the Chronicle had an article a couple weeks back showing higher density in the inner loop than you write. Plus, Houston is supposed to grow by 3 million people over the next 30 years. A transportation system can take decades to build. I think not being more heavily reliant on rail is just short-sighted.

I think you can spin things anyway you want. But to me, HOVs are not a solution - neither is congestion pricing. These are band-aids that address provlems for 10% of the people and skew our transportation system so that it favors the well-off. I feel like I speak for thousands if not millions of people when I write that I do not like HOV, congestion pricing, buses, or the like. Commuter rail, and rail in general, is a viable option. I don't understand your bias against it.

At 10:46 PM, March 28, 2007, Blogger Max Concrete said...

The lack of grade separations at major arterial intersections has been somewhat perplexing to me. I remember discussions of a separation at Voss and Westheimer going back to the 1970s. Of course that never happened. Arterial street grade separations also seem to be rare in other American cites.

A contract was recently awarded for an underpass at FM 1960 and Kuykendahl. The price, $18.5 million for construction, probably explains why we see so few.

Still, I agree with the premise of the study that there should be some way to reduce the cost of these separations so we can build more to unjam bottlenecked intersections. I'm inclined to believe that going up (rather than down) would be better in Houston to eliminate the need for pump stations. I have seen those low-clearance underpasses in suburban Paris. They could have merit, but I would still lean toward overpasses.

At 10:58 PM, March 28, 2007, Blogger Tory Gattis said...

Yes, inside the Loop is a bit more dense - maybe 4,000 per sq.mile? Still half of the *minimum* required for effective rail. Congestion priced lanes can move far, far more people far more cheaply to job centers all over the metro using buses and vanpools. You'll find a summary of my commuter rail arguments here:

At 9:32 AM, March 29, 2007, Blogger Tory Gattis said...

Max: I agree. Voss and Westheimer would be a great candidate, among many others. But I think underpasses are preferred for noise and aesthetic reasons. In a purely commercial intersection, I agree a small overpass probably makes more sense, but in many places, I think people would prefer a low underpass.

Also: the problem with an overpass is that it has to get to the full 16ft clearance, since trucks and buses will have to go under it - but trucks and buses can stay at the surface through the intersection to go past a low-clearance underpass.

At 2:01 PM, March 29, 2007, Anonymous Anonymous said...

anon says
"congestion pricing
.....skew our transportation system so that it favors the well-off"

how does allowing those that can afford to take a larger part of the burden of building roads to do so, favoring the well off or hurting the poor?


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