Sometimes in designing walkways and cycleways and streets and roadways it’s easy to get caught up in details and lose sight of the overall goals. I even ran into this problem as I was writing this and had to continually de-detail. It’s human nature I guess.
Fundamentals are important because it’s important that we understand why something is designed the way that it is, not just copy it and try to adapt it to our U.S. system of roads.
For cities, counties, and states who believe that pedestrians, the disabled and people riding bicycles are important and that we should provide safe facilities for them, there are three key fundamentals—Safety, Momentum, and Comfort.
Note that in using the term cycleway I’m referring to facilities for use by bicycle riders and disabled folk on personal mobility devices that can travel about 10-20 mph.
Safety is likely the number one reason people mention for not wanting to ride to local stores or for not allowing their children to ride to school. Feeling safe and being safe, physically and socially, is number one for nearly every person who does, or wants to, ride a bicycle. If people don’t feel comfortably safe, little else matters.
Cars, and the people driving them, are what make most people feel unsafe and are indeed the number one actual threat. Fatalities or serious injury from other incidents, that do not involve people driving cars, are near zero. For most people then, safety begins with protection from cars and trucks and the debris thrown by their tires.
Painted lines and symbols do not provide this protection, especially if traffic is moving more than about 25 mph. Even if we could rely on drivers to always drive perfectly there would still be problems with debris which can be dangerous.
Physical protection and segregation from motor traffic then is key. On 30 mph streets a curb separated cycletrack may suffice while at 35 mph and above we’ll need increasing segregation depending on motor vehicle speeds and volumes. Adapted from the Dutch CROW Manual:
Bicycle Facilities By Speed
|Below 20 MPH||Bicyclists and motor traffic can often comfortably co-exist. Note that this is 18 mph in NL.|
|Above 20 MPH||Painted bike lanes may suffice if traffic volume is low.|
|Above 25 MPH||Physically segregated cycle track or path. Segregation provided by curb, parked cars, trees, planters, grass median, or a combination.|
|Above 35 MPH||Distance segregation (sometimes combined with physical segregation) becomes critical with separation distance increasing with vehicle speed and volume. This gives drivers increased time to react if they wander, reduces noise problems for cycleway users, and reduces problems of rain/snow wakes and debris from passing cars.|
Junction design is as important as the path between them. Grade separation such as the cycleway going underneath a road is the best option though not always practical. At-grade intersections require separation in time—using proper signal timing to prevent dangerous conflicts. As well, proper placement of stop lines and crossings, utilizing tabled crossings that are slightly raised, and using a consistent color throughout, all improve safety.
For more on Junction Design: Dutch Junction Design
A key element of safety that we often forget is eliminating ambiguity and ridiculousness. It should be clear along EVERY corridor where bicycle riders and disabled should be (for example, bicycle lanes/paths being solid green), every junction with more traffic than maybe 1 vehicle per hour should include sharks teeth or other elements to make right-of-way clear and unambiguous. Unnecessary stops where yield will suffice should be eliminated as should long waits to cross empty stroads.
Commentary: While the approach of The Netherlands and increasingly of other European countries is to prevent injuries and fatalities by making bicycling safe enough that riders do not feel a need to wear safety gear, the approach in the U.S. is just the opposite. Instead of providing a road system that reduces the likelihood of crashes, we tell people riding bicycles to wear a fairly useless helmet and throw our hands up and say that ‘crashes happen’. That needs to change.
Momentum – Stops, Bumps, and Buttons
Most people want to get where they are going fairly quickly and efficiently. For bicycle riders, maintaining momentum is critical to both of these.
Every stop or slowdown, every break in momentum, requires a bit of extra physical effort to get going again and adds extra delay to the trip, far more so than for motor vehicles. By themselves, each is mostly just annoying, numerous of these breaks combined though, become an issue.
A well designed bicycle network, more so than our road network, minimizes elements that cause breaks in momentum. These include the need to stop (or push a button), slow down to deal with a poorly designed or unnecessary curb-cut, slow or stop for cars or trucks blocking a path, slow down because of too tight of a curve or dangerous obstructions in the path, or any number of things.
Cycleways should be designed to allow for safely maintaining momentum at about 15 to 18 mph or faster. Paths should be smooth and continuous in color (usually green in the U.S.), material, and grade for their entire length, including every driveway and minor road crossing.
Paths should be wide enough to allow for safe passing even when someone is coming from the opposite direction.
At major signalized or stop-sign controlled intersections that cannot accommodate grade separation, the path should ideally cross at path grade (tabled crossing) or the transition (curb cut) should be full path width, as gradual and smooth as possible and should never have a reverse slope bump.
Intersections with significant bicycle, disabled and pedestrian traffic should include safe crossing signals in all signal phases. With low levels of bicycle traffic where a beg button may be necessary, the system should provide crossing as soon as possible, particularly if it’s raining or very cold, and should allow enough time for crossing. An advanced ride-by button, along the path about thirty feet prior to an intersection can be of immense help as can countdown timers that let cycleway users know how long before they’ll get a green and how long before it turns back to red.
Generally, cycleway users should never be required to stop anywhere adjacent motor traffic does not.
Here’s a great example of a route in to a city that demonstrates elements of safety, momentum, and comfort. Text and a sped up version Here.
Traffic engineers should think of these as bicycle roads, not recreational paths.
Comfort – Safety, Bumps (tiny and huge), and Shade
If riding a bicycle is uncomfortable you’ll not want to ride very often. If the path is, quite literally, a PITA, or you’re scared out of your wits that you’ll be killed by someone driving a car, you’ll not want to ride your bike to lunch. If you can’t talk to your friend while riding because the path is too narrow or motor noise is too great you’ll be less inclined to ride.
Some things that increase comfort.
Smooth – No jarring bumps. Bumps are a particular problem for people carrying stuff home from the store. Some things we prefer stirred, not shaken. A broken bottle of wine is not welcomed. This can be a particular issue for disabled folk and seniors.
Sociable – Cycleways wide and clear enough, and far enough from noisy traffic, that two people riding to lunch can ride side-by-side and carry on a conversation and not have to single-up every time someone comes from the opposite direction or needs to pass.
Unambiguous – Anything that makes knowing where to go easier. Making paths and crossings a solid color (green in the U.S.), clear signage, clear crossing signals, sharks teeth to indicate right-of-way. Same for cars – make it clear where cycleways are and who has right-of-way.
Consistent – Consistency of design, markings, and signals, particularly along a specific route, is good. However, we should not be afraid to make improvements because they would be inconsistent. The Netherlands has already done much of the work for us. If we’ll follow their lead we’ll go through many fewer changes in the future.
Shade – There is almost nothing more welcome on a hot sunny day than being able to ride under a canopy of trees. Amazingly, these same deciduous trees allow the warming sun to shine through in the winter—that’s good design.
Wind Protection – If there is a prevailing wind then a fence or routing a path so that buildings and trees provide some protection is a very welcomed feature.
Wake Protection – There’s nothing quite like riding along and getting doused in snowy salty slush from a passing car.
Flat – Ideally we’d all have perfectly flat cycleways everywhere we go. Sadly, this doesn’t even happen in The Netherlands. However, anything to smooth out hills and valleys is welcomed. Even just building it up a bit through a valley and cutting through a hill a bit can help immensely. Bridges across valleys and tunnels through hills are that much better. Sometimes riding an extra mile to avoid a big hill is a good option to have.
Rain/cold Priority – Signals that sense when it is raining, snowing, or extremely cold and give pedestrians and bicyclists higher priority than usual.
Foot and hand rests – A rail (low for feet or higher for hands) beside a path just before major intersections allows riders to more comfortably stay on their seat. While this seems amazingly minor, it is amazingly appreciated. This also increases safety, particularly for elderly.
There is a lot of interplay between these. A safer design provides for better momentum and a higher level of comfort. Higher comfort provides for better safety and momentum. Many design elements support all three. A tabled crossing increases safety, momentum, and comfort and does so in numerous ways.
As we’re designing bicycle networks we need to think about these three key fundamentals. Every part of a design should insure that bicyclists are safe and feel safe, that they can maintain their momentum, and that they can ride as comfortably as possible.
Every street and roadway in the U.S. should be designed so that an 8-year-old can ride a bicycle safely and feel safe doing so.
 Statistically, intersections are more dangerous than the path between them. However, for many bicycle riders, intersections may feel and may even be safer because we have more control over our fate. Riding between intersections we have little control over our interactions with vehicles coming from behind, at intersections we can stay on the sidelines and choose when to interact based on our own preference for safety.
 From a stop to 11 mph requires about the same extra energy as maintaining 11 mph for 1/2 mile. So each stop effectively adds about 1/2 mile to our trip from the amount of energy required. Getting going again on an uphill segment can require many multiples as much energy as maintaining speed on the same grade.
 This is a particular issue when temperatures are below about 40f or over 80f when breaks in momentum can have a dramatic impact on our body temp. When it’s hot or humid each stop not only causes us to get hot but increases sweat, not something we want if we’re riding to work in a suit. In colder weather these breaks can cause us to cool down which is not just uncomfortable but can cause muscle cramps.