Pedestrian Traffic Engineering Principles
How the Mayor’s Path Through the Bosque Will Run Pedestrians Out, Increase the Crime Rate, and Complete the Ecocide We Started
- A Surfaced Graded Trail Induces Travel
Traffic engineering formulas say for every 10 feet you widen a highway, you increase traffic by 3.3 percent.[i]
The Paseo del Bosque is a bicycle trail adjacent to the bosque. The mayor’s proposed 10-foot-wide graded and surfaced trail within the bosque falls under this traffic engineering rubric.
The city says 780 cyclists a day pass under I40 on the Paseo del Bosque. Three point three per cent of that is nearly 25 cyclists a day. So the minimum induced travel on the mayor’s proposed path would be 25 cyclists a day. Given a 12 hour day, that’s one cyclist traveling through the bosque every half hour.
A much more likely scenario is that half of the Paseo del Bosque cyclist traffic will use the mayor’s proposed path, for 390 cyclists a day. Given a 12-hour day, that works out to 32.5 cyclists per hour traveling through the bosque, about one every two minutes.
A reasonable scenario would be that the path doubles cyclist traffic adjacent to and within the bosque, such that 780 cyclists a day use the Paseo and 780 a day also use the inner bosque trail. Given a 12-hour day, that works out to 65 cyclists traveling through the bosque per hour, or just over one cyclist per minute.
2. Cyclists Run Pedestrians Out, No Pedestrians Increases Crime
The proposed 10-foot wide path, when shared, would be safe neither for pedestrians or cyclists.
Pedestrians cannot and do not use multi-use trails.[ii]
Albuquerque has done a survey of conflicts between users of its many multi-use paths. This is what the then trails coordinator had to say on the international pedestrian engineering listserv, Pednet:
Here in Albuquerque, New Mexico we have over 80 miles of paved multi-use trails. The weekends are the worst times for user conflicts due to the varying speeds of users,i.e. rollerblaers and bicyclists vs. walkers and runners. The only solution is either separated paths or wider paths, say 14 feet. Otherwise it will forever be a problem.
We recently completed trail counts and surveys. 368 surveys were collected and many of the comments were “please make the trail wider and smoother”, and this was from rollerbladers and bicyclists. Most walkers and runners would actually prefer an unpaved surface, since it is easier on your hips, knees, and ankles vs. walking or running on concrete or asphalt.
This is obviously not a full blown study but I can assure you that the data
we’ve collected here over the past two weekends is indicative of the needs and conflicts which exist nationwide on trails whether they be in urban or more off-road/wilderness areas.
Hope this is useful and helpful.
Henry N. Lawrence III
Associate Planner, Trails Coordinator
City of Albuquerque Parks and Recreation Dept.
City transportation planner Julie Luna confirms this is the only study Albuquerque has made of conflicts between users of trails.
“Shy space” or “shy distance” is a term used by pedestrian traffic engineers to calculate safe widths for sidewalks, trails, and bicycle lanes. One fast-moving pedestrian such as a runner requires three feet of shy space. Give that runner a dog, who also requires three feet of shy space, and six feet of shy space are required for just two pedestrians.
On a 10-foot-wide trail such as the one the mayor proposes, that leaves four feet of shy space for one cyclist to pass the slower-moving pedestrians. Best practice traffic engineering principles for cyclists recommend six to eight feet of shy space for each one. Any trail through the bosque that would safely allow both cyclists and pedestrians to use it would need to be 12 feet wide at a minimum, or 14 feet wide as the Albuquerque trails coordinator suggested.
Crime increases as pedestrians decrease. Out of the line of sight of motorists, a cyclist-only bosque would harbor increased assaults under the well-documented public safety rubrics of “eyes on the street”. [iii]
A 14-foot-wide trail through the bosque would induce even more cyclist travel, decrease pedestrian travel, and increase crime.
3. Animals and Birds Flee Increased Human Contact
These statistics can best be calculated by the many professional naturalists who oppose the mayor’s path. Gale Garber of Hawks Aloft Inc. has scientifically surveyed bird life in the Rio Rancho bosque since so-called invasive plants which provide nesting habitat were removed, and a crusher fine trail installed. The reduction from over 700 summer birds per 100 acres to under 200 in just eight years cannot be accounted for by drought alone.
The minimum induced travel of one cyclist per half hour twelve hours a day – much less the maximum of one cyclist every minute – would have a permanent damaging effect on the safe nesting habitat of birds, mammals and reptiles in the bosque.
[i] For a survey of the scientific literature on induced travel Google this.
For an August, 2013 report, see Todd Litman, Generated Traffic and Induced Travel: Implications for Transport Planning, Victoria Transport Policy Institute.
[ii] For the Federal report on conflicts between users of multi-use paths Google this:
[iii] For “eyes on the street”, “shy space” and “barrier effect” outcomes, see the most recent best practices guide recommended by the experts at the international pedestrian traffic engineering listserv, Pednet: Pedestrian and Bicycle Planning: A Guide to Best Practices, Victoria (B.C.) Transport Policy Institute. Their director, Todd Litman, is thought by senior pedestrian traffic analysts to be among the most solid analysts now at work.