Tuesday, November 25, 2008

Puzzling pedestrian pronouncements

Yesterday evening, I rode east from downtown as usual on Liberty Street. One-way eastbound, it has four travel lanes and a left-side parking lane from Second Street to Preston Street. Between First Street and Preston Street, both of the two rightmost lanes become right-turn-only. These two lanes carry heavy traffic to the interstate highway on-ramp between Floyd Street and Preston Street, and to right-turn destinations before the ramp. To avoid the heavy traffic and make my path obvious, I ride in the third lane from the right - the rightmost lane that serves my destination. Just east of Preston Street, the right-turn lanes disappear and this becomes the right-hand through lane.

As I rode in the middle lane of Liberty Street near 1st Street, a pedestrian on the sidewalk shouted, "Get out of the street!" I smiled at the absurdity of it. I was riding at 21 mph, keeping up with most of the traffic. No vehicles were waiting behind me; as usual, 90% of the traffic drove in the lanes to my right, and the remaining cars chose to pass me on the left. Had I attempted to ride at that speed on the sidewalk (even if that were legal), I would have terrorized any pedestrians including the one who would have me get off the street. My riding on the street created no possible inconvenience or hazard for the person on the sidewalk. What motivated him to show disdain for my riding on the street?

Would he have shouted had he seen a bicyclist near the right-hand curb? I don't know. A construction worker in a building shouted at me to get out of the traffic lane on Muhammad Ali Boulevard one morning a few weeks ago. Again, I could not conceivably have been causing him any difficulty or delay. Again, no traffic was "stuck" behind me. A few years ago, a man standing at a bus stop on Frankfort Avenue shouted at me to get off the road. That time, I was riding far enough to the right to allow overtaking vehicles to pass me easily. I stopped and asked him why he thought I should not ride on the road. "You slow down traffic," he said with certainty. (I disagree - a topic for another post.)

Kentucky averages 53 pedestrian deaths per year due to car crashes. I have never heard of a pedestrian in Kentucky killed by a bicyclist. (If you know of one, do tell - I don't want to spread misinformation.) Pedestrians ought to appreciate people using bicycles instead of cars to get around. Even if I did slow traffic, thoughtful pedestrians should celebrate that, rather than berate me for it. Faster traffic increases the number and severity of pedestrian crashes.

In fairness, many pedestrians have shouted encouragement as I rode hard to keep up with the traffic lights, asked me about my unusual bikes, or said, "Cool bike, mister!" They have thanked me for yielding to them in crosswalks and commented on my bright headlight. Sometimes we will nod or wave to one another.

Somehow, though, I feel that the pedestrians who take offense at my riding in the street reflect a widespread notion that we need to address. That notion says that speed trumps safety, civility, patience, and diversity. You have a right to the road only if you can maintain the speed limit. If your finances or beliefs or preferences compel you to travel somehow other than by private motor vehicle, you need to stay out of the way of the cars - the legitimate road users. Even when a bicyclist keeps up with traffic and takes pains not to delay motorists, the notion holds. People tend to reject information that challenges their preconceived ideas.

Roads and intersections and traffic signals designed to accommodate bicyclists make our lives easier and safer. I celebrate any improvements in these facilities. Still, if we really want to make bicycling a viable option for a broad swath of our society, we need to overturn this prejudice that makes even some pedestrians look askance at bicyclists on the streets.

Friday, November 14, 2008

Seeing red, part 4: trying but not succeeding

Louisville Metro government has had bicyclists serving in some key bicycle-related planning and engineering jobs since 2000. They have understood most or all of the problems discussed in the past 3 posts about traffic signals. They have tried at least three solutions thus far. Why, then, do we still have problems with red lights here?

Some of the newer inductive loop detectors at Louisville traffic signals use the quadrupole loops recommended in the website on bicycle-sensitive traffic detectors. You can tell the quadrupole loops by the three parallel black lines in the pavement along the direction of travel (photos of traditional dipole and new quadrupole designs, called "figure 8 loops" on that page). You can see them, for example at the intersections of Pee Wee Reece Road and Taylorsville Road (near Bowman Field - map), E. Liberty Street and Baxter Avenue (map), and Spring Street and Payne Street (map).  Unfortunately, the design details of the quadrupole loops in Louisville result in at least half of them (including two of these three) failing to trigger for bicycles. Some that will detect bicycles (such as the one at Liberty and Baxter) require a bicyclist to place one wheel at exactly the right location, often beyond the stop bar. Merely switching from dipole to quadrupole loops does not solve the problem - the physical and electrical details of the loops need to be right.

A couple of years ago, Metro installed experimental bicycle-sensitive loop detectors on Spring Street on both sides of the intersection with Mellwood Avenue (map). Spring Street, a marked Bicycle Route, has bike lanes on each side. Metro installed the bicycle-sensitive loops in the bike lane, which makes sense only until you recognize that a bicyclist heading northwest (toward downtown) on Spring Street needs to merge left into the main travel lane to keep from getting hit by motorists turning right from Spring Street onto Mellwood Avenue. I don't like a design that forces bicyclists to choose between triggering the light and risking getting right-hooked. In addition, Metro never marked the pavement or in any other way informed bicyclists of the purpose or location of the bicycle sensors. Most local bicyclists I know have no idea the sensors exist until I mention them.

This year, a block away and with equally little fanfare, Metro installed pushbuttons on Spring Street/Adams Street at its intersection with Story Avenue (map). A bicyclist facing a red light on Spring/Adams can pull over to the curb, hit the button, and wait only a few seconds for the light to change. (The buttons work.) Alas, this again requires the bicyclist to ride to the right-hand edge of the street. For a bicyclist riding NW on Spring Street, this causes no problem because traffic on the intersecting street (Story Avenue) goes one-way to the left. For a bicyclist riding SE on Adams Street, though, motorists coming from behind may turn right and hit the bicyclist who has just ridden from the curb after pushing the button. To use the button, the bicyclist must take an unsafe position on the road. As with the bicycle-sensitive loop detectors a block away, no signs or pavement markings alert bicyclists to the existence or function of the button.

In all of these cases, I suspect that it would have cost Metro no additional money to install a bicycle-sensitive loop detector as the traffic detector in the middle of the right lane. It would have cost a bit more to add the necessary bicycle logo (scroll to the bottom of the page) to mark where bicyclists should stop to trigger the light. The problem: some traffic engineers don't believe that bicyclists and motorists can ever be trained to accept the validity of a bicyclist riding in the middle of a vehicular traffic lane, even if only at an intersection. It's time to try a well-designed, adequately funded educational campaign to raise public awareness and change behavior of motorists and bicyclists. Sometimes, education can accomplish goals that engineering cannot. 

Sunday, November 9, 2008

Seeing red, part 3: Sensor-actuated signals

Take a look at the road surface when you approach a traffic signal. If you see a tar outline of a rectangle with cut-off corners, the road holds a coil of wire that acts as a metal detector to trigger the traffic signal. If a car stops on top of that metal detector (a.k.a. inductive loop sensor), the car will trigger the light to turn from red to green. But what if a bike stops on top of the sensor? Usually, nothing at all.

When an electrical engineer's explanation of bicycles and sensor-actuated traffic signals first appeared online in 2003, I brought it to the attention of Metro traffic officials. The article explains how to make the loops sensitive enough to detect bicycles without getting triggered by larger vehicles in adjacent lanes. It also tells how to mark streets to show bicyclists the "sweet spot" of the sensor. Several cities have made bicycle-sensitive loop detectors their standard. The Louisville Metro Complete Streets manual approved in 2007 mentions bicycle-sensitive signals once, but does not require or recommend making all sensor-actuated signals sensitive to bicycles.

How much of a problem is this? If you don't care about whether bicyclists stop at red lights, then you probably won't rank it high on your list of necessary improvements to our bicycling environment. I make a point of riding according to traffic law, and these bicycle-ignoring signals drive me crazy. Here's a short top-of-the-head list of signals that I can't trigger, no matter where I place my bicycle on the sensors: Spring Street at Payne Street; Payne Street at Baxter AvenueCountry Lane and Brownboro Road (in front of Doll's Market); North Bellaire Avenue at Frankfort Avenue; and Hillcrest Avenue at Frankfort Avenue. The light at Hillcrest and Frankfort is even more crazy-making, because it flips back from green to red 2 or 3 seconds after a motor vehicle gets off the sensor. A bicyclist waiting behind a motorist at this red light can make it through on green only by tailgating the motorist and sprinting.

I expect that Louisville Metro and the surrounding counties have hundreds of intersections controlled by sensor-actuated signals. Maybe half of these signals will trigger for a bicycle placed at exactly the right spot; the others won't trip for an individual bicycle, ever. These sensors usually get replaced whenever the road is repaved. It costs little to make the new detectors bicycle-sensitive. City, county, and state traffic engineers: Please build signalized intersections that work properly for bicyclists. How can you expect us to obey red lights that don't recognize our existence?

Friday, November 7, 2008

Seeing red, part 2: timed lights

On several one-way streets in downtown Louisville, traffic signals are timed to allow vehicles to proceed at a steady speed through a string of intersections without needing to stop for any red lights. These synchronized traffic signals work well as long as the vehicles can maintain that set speed within a few mph.

In my experience, I can ride through 6 or 7 green lights in a row on some of these streets if I ride fast: at least 23 mph. On my commuting bicycle, I simply can't ride that fast. Yesterday, I did some measurements and calculations to learn how fast a bicyclist needs to ride to keep up with the traffic signals, and if any slower-than-car speed could allow a bicyclist to cruise through all green lights.

For the test case I used East Main Street, a common commuting route with a bike lane. The signals are timed to allow a driver going at 34 mph to go from a green light at one intersection to green lights at all of the following intersections. Riding at 24 mph, one would fall behind the signals by about 5 seconds each block plus another 5-10 seconds delay if you need to start from a full stop or a low speed. This fast rider would get through about 7 intersections before getting stopped by a red light. At 20 mph, a rider would get through about 5 intersections before encountering a red light; at 15 mph, 3 intersections; at 12 mph, only 2 intersections before needing to stop again. How slowly would you need to ride to encounter all green lights? You would need to poke along at less than 10 mph.

Someone riding from the east end of Market Street to 3rd Street, for example, would have red lights add 1 minute to the trip if she or he rode at 20 mph. Red lights would add 2-1/2 minutes to the travel time for a 12-mph bicyclist. That comes to a 30% time penalty for the 20-mph rider, and a 40% time penalty for the 12-mph rider.

If Metro re-synchronized the signals for a 25 mph speed limit (instead of 35 mph), the 20 mph bicyclist could get to 3rd Street or beyond without stopping, and the 12 mph bicyclist would arrive one minute sooner. But what about the motorists who could drive at only 24 (instead of 34) mph? The travel time difference for this 10-block trip would be 51 seconds.

Bottom line: If Louisville (or another city with synchronized downtown traffic signals) wants to make its downtown safer and more accessible to bicyclists and pedestrians, they need only re-time the traffic signals for a lower speed. This will decrease the number and severity of car crashes (including crashes with bicyclists and pedestrians), make it much easier for pedestrians to cross the street, and allow bicyclists much less delay due to red lights. The cost - a minor inconvenience to motorists.

Monday, November 3, 2008

Seeing red

Most major streets in greater Louisville meet at intersections controlled by traffic signals  ("signalized intersections" in traffic engineering lingo). In spite of the number and severity of crashes at signalized intersections, the inconvenience of stopping at red lights regardless of traffic volumes, and the high cost of building and maintaining these intersections, I took them for granted until recently. It seemed as though they must improve traffic flow and safety compared to other options (stop signs, for example) or else the traffic engineers would stop using them. I certainly don't want a more chaotic traffic environment than we have now.

As regular readers know, I prefer modern roundabouts (not traffic circles) to signalized intersections in many situations. I believe that one-lane roundabouts could replace many of the traffic signals in our area with benefits for motorists, bicyclists, and pedestrians. Of course, a transition from signalized intersections to roundabouts would cost money and involve controversy. Even in the best-case scenario, we will have lots of traffic signals for years to come.

As long as we use traffic signals, we need to make them functional for all legal road users. In Louisville, we have two basic types of traffic signals: signals timed to turn from red to green on a fixed schedule, which might differ for different times of day (for example, morning rush hour versus evening rush hour); and signals that stay green for traffic along the more major street until a sensor detects vehicles waiting on the smaller street. I'll call the first type "timed signals" and the second type "sensor signals." Locally, very few signals of either type work well for bicyclists. Tomorrow, I'll explain the problems and explore solutions.