Engineering and Design Elements
In the context of this report, engineering means designing and building infrastructure (streets and other public spaces) that is safe, convenient, accessible, and comfortable for pedestrians and bicyclists to use. Infrastructure and facilities (e.g., sidewalks, bikeways, and trails) are often the most visible element of government support for walking and biking modes. Similarly, adequate facilities are often mentioned as a required element for those who do not walk or bike. This chapter highlights numerous examples of street design and engineering that the scan team noted during the scanning study as conducive to pedestrian and bicyclist safety and mobility.
Implementing Foreign Design Practices in the United States
Some policies, practices, and designs are easily transferrable and can be immediately implemented. However, implementing some foreign policies and design practices in the United States may require a safety evaluation and/or implementation criteria. For example, separated bicycle facilities should be evaluated in the context of typical motorist and bicyclist behavior and safety experience in the United States before being widely implemented. Separated onroad bicycle facilities may be quite effective in Denmark, for example, but their effectiveness may be at least partly a product of Danish culture and behavior or a result of their widespread implementation.
However, foreign practices (like separated bicycle facilities) should not be dismissed outright simply because current American culture and behavior may be different. Culture and behavior can be changed, but these changes often occur over longer time periods than covered in a typical safety evaluation. For example, separated bicycle facilities could be evaluated at a few trial locations in the United States and show no clear safety benefits in a typical 1– to 2–year safety evaluation. But in 5 to 10 years, as more bicyclists use separated facilities and motorist and bicyclist behavior adapts, safety could improve dramatically. Unfortunately, this increase in safety would not be captured in typical safety evaluations because they do not capture long–term behavior changes. Many of the host countries have undergone a culture change over the past 40 years that has returned to an increased emphasis on walking and bicycling safety and mobility. Changes of this sort can happen if fostered by a careful, evidence–based approach.
False Sense of Security and Safety
The foreign hosts gave thoughtful consideration to a “false sense of security and safety” when designing pedestrian and bicyclist facilities. This expression was mentioned numerous times by the engineers and planners responsible for facility design details. The host countries are not rashly constructing facilities in an effort to promote walking and bicycling without regard for safety. In fact, some host countries are paying meticulous attention to crash and injury data to determine which road designs are safest for pedestrians and bicyclists. For example, Sweden has implemented nationwide the STRADA (Swedish Traffic Accident Data Acquisition) database that integrates police crash data and hospital admissions data. The STRADA database addresses the underreporting problem common to walking and biking, and gives Swedish engineers and planners a more complete picture of walking and biking safety.
Engineering and Design Elements for Pedestrians
The scan team observed several innovative traffic signal features and design practices that have the potential to improve pedestrian safety in the United States. This section highlights numerous examples of engineering and design elements for pedestrians that are not commonplace in the United States.
The PUFFIN (Pedestrian User–Friendly Intelligent) crossing is the newest type of pedestrian traffic signal in the United Kingdom and includes several design features intended to improve pedestrian safety:
- Near–side pedestrian signal head (figure 10) that encourages pedestrians to view oncoming traffic
- Simplified pedestrian signal phasing that includes “green man” (walk) and “red man” (don’t walk) phases, but eliminates a flashing “don’t walk” (i.e., don’t start) phase
- Passive detection of pedestrians (figure 11) in crosswalks, waiting areas, and landings to truncate, extend, or cancel the pedestrian phase at traffic signals
- An indicator light that confirms when the pedestrian signal has been activated
- Tactile signal phasing indicators for visually impaired pedestrians
In the United Kingdom, PUFFIN crossings are being phased in to replace the typical pedestrian traffic signal, which is referred to as a PELICAN (PEdestrian LIght CoNtrolled) crossing. A Department for Transport brochure indicates that the PUFFIN crossing has these benefits:
Safer for Pedestrians:
- The sensors that see you at a PUFFIN crossing also control the traffic lights.
- Because there is no flashing red traffic light sequence, drivers can no longer start to move until you have finished crossing.
- You can see the pedestrian signal and watch traffic approaching at the same time.
- Partially sighted pedestrians can see the near–side pedestrian signals more easily than a signal on the other side of the road.
Better for Drivers:
- Traffic lights change to green as soon as the crossing is clear, so drivers will no longer be stopped unnecessarily if there are no pedestrians in the road.
- Traffic won’t be stopped if pedestrians push the button and then cross the road before the traffic lights change to red, or if they push the button, then change their mind and walk away from the crossing.
Offset or Staggered Pedestrian Crossing
The design of an offset or staggered pedestrian crossing places oncoming traffic in the crossing pedestrian’s field of view so the pedestrian is more likely to notice it. Offset pedestrian crossings (figure 12) can be used at both signalized and unsignalized crosswalks. Depending on site conditions, the offset can be a right angle or skewed. The most important design feature is that the offset forces pedestrians to walk longitudinally in the median for a short distance so they face oncoming traffic.
Near–Side Traffic Signals
Near–side traffic signals for motor vehicles are common in all of the countries the scan team visited. The near–side traffic signals are mounted on cantilever support arms (over the traffic lanes), as well as on shorter poles mounted on the side (and median, if present) of the street (figure 13). The foreign hosts indicated that near–side traffic signals are effective at reducing motorist encroachment on the pedestrian crosswalk. For example, at most intersections, motorists are unable to see the traffic signal if they stop too far forward in the pedestrian crosswalk. There was discussion that near–side traffic signals are more visible to approaching motorists and provide a visual target at the appropriate stopping point (before vehicles enter the intersection). There was also discussion that far–side traffic signals may actually induce more red–light running, since the visual target is on the far side of the intersection. The hosts did not provide any safety data on this topic, only anecdotal experience.
Research in Sweden by Ekman and others has concluded that raised crosswalks at unsignalized crossings can be more effective than other traffic control devices (like flashing beacons) because they control speed at the actual pedestrian crossing. Consequently, slowed vehicles are more likely to yield the right–of–way to crossing pedestrians. The scan team observed the use of raised crosswalks in several countries (they were most common in Sweden and the United Kingdom) at midblock locations, roundabouts (figure 14), and entrances to traffic–calmed districts. In Sweden, there has been some opposition from drivers of emergency response and other large vehicles (like buses and trucks) to the raised crosswalks on major arterial streets. A unique feature of the raised crosswalk in figure 14 is that drivers have to slow down to mount the crosswalk, but the slope is gradual so drivers are not jolted at slow speeds. This was done to address the concerns of large vehicle operators.
Crossing islands, used most often by pedestrians and sometimes by bicyclists, are a common design element in the United States, but the frequency of use appeared to be greater in Europe (especially in the United Kingdom and Sweden). Crossing islands (sometimes with internally illuminated bollards) appeared to be used more often, even when confined or limited street space required the use of smaller islands (figure 15). Most crossing islands were accessible to people using assistive devices for walking. Another common sight was the use of crossing islands at midblock locations without crosswalk markings.
Pedestrian railing was most common in the United Kingdom (figure 16), where it was used to direct pedestrian movements to preferred crossing locations at intersections and in median islands. It also offered a useful guide to pedestrians with visual disabilities. The railing appeared to be most common in areas with high pedestrian traffic (e.g., London).
Pedestrian walkways and plazas, particularly in Copenhagen, offered two smooth surfaces for pedestrians on foot or using assistive devices for walking (figure 17). This technique offers an option for communities seeking to incorporate historic surfaces such as cobblestone into their sidewalk system while complying with the Americans With Disabilities Act (ADA). Another practice observed in Copenhagen was a guide strip for wayfinding by pedestrians with visual disabilities that tracked through intersections and to the steps of important public buildings (figure 18). Scan team members also observed that truncated domes in Copenhagen were constructed of metal rather than rubber. The Swedish city of Malmö provided tactile diagrams of street crossings at several intersections (figure 19) that offered advance information for a safer crossing. In Bristol, United Kingdom, a tactile rotating knob (figure 19) was located on the bottom of near–side pedestrian signals to indicate when the crossing phase had started.
Engineering and Design Elements for Bicyclists
The scan team observed several innovative approaches and design practices that could be used to improve bicyclist safety in the United States. This section highlights numerous examples of engineering and design.
Separated bicycling facilities were in use in all five of the countries visited during the scanning study. The designs differed between countries and sometimes at different locations within a country. For the purposes of this report, the separated bicycle facilities are classified into these categories:
- Cycle track— A one–way exclusive bike lane that is separated from motor vehicle traffic by a curb and has an elevation slightly above the motor vehicle lane but below the pedestrian walkway or sidewalk. Cycle tracks sometimes transition to onstreet bike lanes as they cross street intersections. Cycle tracks were most common in Copenhagen, Denmark (figure 20).
- Cycle path— A one–way or two–way exclusive bike lane located parallel to an existing street, but separated by a full–height curb. Cycle paths are typically at the same elevation as the pedestrian walkway or sidewalk, but are often differentiated by a distinct color. In some cases, the cycle path was located on the outside of onstreet parking or onstreet transit stops. The scan team saw numerous two–way cycle paths in Sweden and Switzerland (figure 21) and one–way cycle paths in Germany (figure 22).
- Cycle path on an independent alignment— A oneway or two–way bike path located on an alignment that is independent of the street network (figure 23). When shared with pedestrians and other nonmotorized users, this path is comparable to a shared–use path in the United States.
Several different approaches were used to address bicyclist safety at intersections. The most common potential motorist bicyclist conflict occurs when motorists turn right across a bikeway that goes through an intersection. Another potential conflict occurs when a bicyclist attempts to turn left across motorists traveling through an intersection.
Advance stop lines for bikeways were used in several of the host countries (figure 24). At some intersections, the advance stop line was combined with a leading green phase for bicyclists. The advance stop line provides better visibility for bicyclists because they are positioned in front of turning motor vehicles at the intersection. The advance stop line and bicycle traffic signals also provide bicyclists with a physical and temporal head start, which permits through bicyclists to clear the intersection before motorists turn across the bikeway.
Large trucks often have blind spots along their front and side, and truck drivers have difficulty seeing bicyclists who may be in their path as they turn right across a bikeway. In Switzerland, engineers have developed a heated convex mirror (locally referred to as a “Trixi” mirror for a bicyclist crash victim) that is attached to a signal or utility pole at the intersection (figure 25). The convex mirror enables truck drivers to scan their blind spot before turning right across a bikeway. The bicyclist image size in the convex mirrors is still somewhat small and requires motorist awareness, especially for bicyclists in dark clothing or in low–light conditions. However, motorists’ use of mobile phones and texting devices— a clinically proven distraction—is quite common in the United States and could reduce the effectiveness of the small bicyclist image size provided by convex mirrors. In the United Kingdom, the Department for Transport and other groups distribute an inexpensive Fresnel lens (called TruckView®) that can be attached to the side window of a truck to reduce the chance of a bicyclist being struck in a truck’s blind spot.3
Bike boxes (also called “Dutch pockets” and enlarged bike lanes) are another intersection design element used in several countries (figure 26). The main benefit of a bike box is for left–turning bicyclists who arrive on a red signal phase to position themselves in front of motorists so they are more visible and can clear the intersection before motorists. Most bike boxes have a distinct color as well as a bicycle symbol on the pavement.
Most European traffic signal systems display a short simultaneous red and yellow indication before the green phase. This serves to alert queued traffic in advance of the green phase and alerts bicyclists that entering the bike box just before the green phase will likely result in a conflict with releasing traffic. There is no U.S. equivalent of the advance simultaneous red and yellow indication to provide a cue that the signal is changing.
Several U.S. cities are experimenting with bike boxes (e.g., Cambridge, MA; Columbus, OH; New York, NY; Portland, OR; San Francisco, CA). One of the criticisms (at least in the United States) of bike boxes is that they are effective only if the bicyclist arrives at the intersection on the red signal phase, and that they may pose safety concerns to inexperienced bicyclists who try to use them when arriving in the middle of the through green phase. Several host countries dealt with this issue by providing a marked waiting space on the far side of the intersection for left–turning bicyclists to make a pedestrian–style left turn. Conflicts may result when bike boxes are used at locations where right turn on red is permitted (most of the foreign host countries did not permit right turn on red). Right turns on red are commonly allowed in the United States and motorists often do not come to a complete stop, only slow down sufficiently to make the turn. In most countries, right–turn–on–red restrictions for motorists were the norm rather than the exception. That is, right turn on red for motorists was restricted unless otherwise signed. In the United States, right turn on red is permitted unless otherwise signed.
Bicycle Traffic Signals
Bicycle–specific traffic signals were used in nearly all countries (the exception was the United Kingdom) to control bicycle traffic movements (figure 27). The bicycle traffic signals were smaller than the motor vehicle signals and were mounted on both cantilever support arms and short poles behind the curb. In most cases, a bicyclist plaque accompanied the signal or a bicycle symbol was integral to the signal lens cover. From the scan team’s anecdotal experiences, bicyclist comprehension of and adherence to the bicycle traffic signals appeared to be very good. In most cities, the bicycle traffic was dense enough that visiting or inexperienced bicyclists could simply follow the example of the bicyclists in front of them when trying to navigate a complicated intersection. Bicycle traffic signals are used to reduce turning conflicts at signalized intersections and often provide separate and sometimes exclusive phases for bicyclists, such as the following:
- Bicyclists may be given an advance green that precedes the motorist green by several seconds.
- Bicyclists may be given an exclusive green phase in which to make left turns.
- Bicyclists may be given a red phase while right–turning motorists have an exclusive turning phase.
Pavement Markings at Intersections and Conflict Areas
Several different types of pavement markings were used at intersections to reduce conflicts or direct attention to areas of potential conflict. The most common pavement marking was the use of color (blue in Denmark, red in Germany and Switzerland) for bike lanes (figure 28). Colored bike lanes have been tested in several U.S. cities (e.g., Burlington, VT; Cambridge, MA; Chicago, IL; Portland, OR; Seattle, WA; St. Petersburg, FL; Tempe, AZ) as a way to guide bicyclists through complex intersections as well as to make turning or passing motorists aware they are crossing a bike lane. In most U.S. applications, the contrasting color pavement has been used for short sections of the bike lane and not as a continuous color treatment along the entire length of the bike lane. A Danish research study4 (described in Chapter 7) found that the use of one blue bike lane crossing reduces the number of intersection crashes by 10 percent, whereas marking two and four blue bike lane crossings through an intersection increases the number of crashes by 23 percent and 60 percent, respectively. A study of blue bike lanes in Portland, OR, reached the following conclusions:5
Figure 27. Bicycle traffic signals control bicycle traffic movements at signalized intersections in Potsdam, Germany. (Note: A blue plaque placed in the highest signal lens is not intended to control bicycle movements.)
- More bicyclists followed the colored bike lane path.
- Fewer bicyclists turned their heads to scan for traffic or used hand signals.
At a few large intersections, onstreet bike lanes were dashed through intersections (with no fill color) to provide guidance to bicyclists (figure 29).
In Germany, longitudinal bike symbols were provided at driveways and stop–controlled cross streets. These bike symbols were oriented to be seen by motorists turning across the bike lane (figure 30).
Another pavement marking used in Germany was a dashed bike lane line (figure 31). A dashed bike lane is also called an “advisory bike lane” or a “suggested bike lane” in other countries, such as the Netherlands. The dashed bike lane is used on narrower, lower volume streets that do not have sufficient width to provide a full–width bike lane and full–width motor vehicle lanes. Motor vehicles may enter the dashed bike lane to pass oncoming motor vehicles, but must share this dashed bike lane with bicyclists.
Signal Timing for Bicyclists
Copenhagen has several heavily used bike routes on which the motor vehicle traffic signals were synchronized to a bicyclist speed of 20 kilometers per hour (km/hr) (12 miles per hour (mi/h)) (figure 32). As long as a bicyclist maintains this average speed, he or she is very likely to pass through most intersections with a green phase. On the inbound route shown in figure 32, the traffic signals were synchronized in this pattern on Monday through Friday from 6 to 10 a.m. In Danish, this was referred to as “grøn bølge” or “green wave.” Bicycle signal timings can also provide an earlier yellow and red indication to accommodate the increased clearance times bicyclists require at intersections.
Low–Speed Street Design
The scan team observed the use of low–speed street designs in both residential and commercial areas that were especially conducive to walking and bicycling. For example, the city of Bristol, England, has implemented 20 mi/h (12 km/h) “home zones” in its new residential development. A scan team member made a personal visit to Osnabrück, Germany, before the official scan trip.
Figure 29. Dashed bike lane provides guidance through a wide intersection in Osnabrück, Germany.6
Several cities in Germany, Sweden, and Switzerland also have implemented low–speed streets (20 to 30 km/h or 12 to 19 mi/h) in both residential (figure 33) and commercial (figure 34) areas. The host countries have different criteria for applying low–speed street design, as well as different levels of traffic control devices on these low–speed streets.
Several foreign hosts indicated that certain criteria should be met for these low–speed street designs to operate properly:
- relative speeds of the different modes should be similar,
- flows (volumes) of users should be similar, and
- “see and be seen” is a critical design element that encourages increased communication and interaction between modes.
In Bern, Switzerland, motor vehicle access to a low–speed street in a commercial area was controlled by retractable bollards. Authorized users (such as freight delivery personnel or store owners) swiped an access card across a security pad to retract the bollards and gain access (figure 35).
Integration of Biking and Walking With Public Transit
The scan team observed close integration of bicycling and walking considerations with public transit (including intercity rail) that makes longer intermodal commutes by bike practical as well as safer and more convenient. These considerations include the following:
- A variety of bike parking solutions at stations, including plentiful and convenient bike racks, covered outdoor parking, and secure indoor parking (figure 36)
- Policies that permit bikes on trains and buses, even during peak times
- Low–cost or free short–term bike rental or sharing programs located in or near train or bus stations, with involvement in or ownership by the transit agency
- Channels or ramps on stairways that make it easier to use steps while pushing a bike (figure 37)
- Public taxis with quick–mount bike racks for passengers
Outdoor parking next to train station (Lund, Sweden)
Secure indoor parking (Lund, Sweden)
Three–level secure indoor parking (Bern, Switzerland)
Figure 36. A variety of bike parking is provided at transit stations.