Functional Harmony: Service Roads
A short video summarizing some key points.
A map of service roads visited and then discussed in this article.
Service roads are a small roads that run alongside arterial roads. They are used for destination traffic and often for on-street parking. Service roads are not used frequently in America, but they certainly have been used in this way before. On Tremont Street (Fig. 1), there is a service road between Berkeley Street and Lucas Street which separates through traffic from the vehicles accessing the businesses.
Figure 1: A Service Road on Tremont Street. It provides parking off the main road for people visiting the businesses, thus keeping the two through lanes clear.
Service roads provide functional harmony along a roadway in several ways. First, they separate different types of traffic. Haagweg has both through and local traffic. While some people want to go a long distance at a high speed, others are on this street because they live here or are visiting a business. Typically, these two functions do not mix safely or efficiently; it is not harmonious to have some people parking their car, looking for a business, or turning onto a side street while those behind them want to pass through as quickly as possible. This leads to congestion and accidents. By separating these two types of traffic into their own sections of the road (Fig. 2), the road can properly service both through and destination traffic. This transition does not eliminate any lanes, but merely moves one on each side to a separate area.
Figure 2: An aerial view of Haagweg in Rijswijk, NL. There is one through lane and one service road lane on either side of the tram tracks. Street parking is on the service road next to a barrier separating the two roads.
This separation by function is also a separation by speed. The lower speed on the service roads means that this space can also safely be used by bikes. In most cases, cyclists and motorists will go about the same speed here. Thus, these two functions are harmonious and can share the same space. Other design choices are made to ensure that cars drive safely. First, the road is typically narrow. This forces drivers to drive slowly to stay within the lane. It also means that there is not enough space for cars to speed past cyclists. However, the roadway is wide enough for cyclists to safely pass one another. Allowing for two way cycle traffic (Fig. 3) is also important since bikers will often do it regardless, as it is much more convenient than crossing a busy road twice just to go a few blocks back. On Haagweg and Vrijenbanselaan, there are several businesses on one side of the street, so cyclists just want to take the most direct route between them if visiting multiple businesses. However, two-way traffic is not always allowed for mopeds since their larger mass and greater speed would make this unsafe in some areas. Service roads often have a sign indicating that it is a bike road where cars are allowed as guests (Fig. 4), indicating that bikes have priority. This is underscored by the extensive space for bike parking on service roads, but limited space for car parking. More car parking is available in parking lots off the service road though.
Figure 3 (left): A sign on Haagweg indicating that the road is one-way, except for (uitgezonderd) bicyclists.
Figure 4 (right): A sign on Haagweg indicating that this is a bike street and that the car is a guest.
Haagweg’s lane on the service road is 11 feet wide (Fig. 2), making passing a cyclist rather difficult (Fig. 5). Zuidpoldersingel has a slightly wider lane of 13 ft, but this is certainly not wide enough to speed past a cyclist. Vrijenbanselaan is the widest of the three roads visited. It is about 22 feet wide, which will allow cars diving in opposite directions to pass each other. Although wide roads like this could encourage speeding, the curvature and short length of the road limits this possibility. The designers chose to do this since Vrijenbanselaan is a main road that connects two cities. This is meant to entice drivers to use this road for intercity travel, as oppose to local roads. The road accommodates cyclist and pedestrian traffic, but few were found on this road since nearby routes exist that are more suitable for these modes of transportation.
Figure 5: A service road on Haagweg can comfortably accommodate multiple cyclists riding in each direction due to the low motor traffic volume. Safely driving a car down this road is possible, but only at a slow speed. Red pavement is used as an indicator to drivers that this is predominantly a cyclist route.
In addition, special pavement treatment is used to signal to road users that this is a new zone where drivers should drive slowly and watch for bikers and pedestrians. This is done frequently in the Netherlands so that these areas with mixed traffic are recognizable to road users. On Haagweg and Vrijenbanselaan, rather than paving the service roads with smooth, black asphalt, red stamped asphalt (Fig. 5) or brick is used to make this indication. On Zuidpoldersingel, stamped gray asphalt is used to recognize this as a different zone. For even further speed reduction, speed bumps should be placed frequently along service roads (Fig. 6). This is done on Haagweg and Zuidpoldersingel, but not Vrijenbanselaan, again because of the road’s main purpose of serving motor through traffic.
Figure 6: A service road on Zuidpoldersingel in Delfgauw, NL is paved with stamped gray asphalt instead of smooth black asphalt to indicate to drivers to drive slower here. A speed bump is used to grab the attention of drivers and to slow them down.
It is important to design service roads so that vehicles make 90 degree turns to enter or exit them. This is done to force vehicles to slow down and watch pedestrians and cyclists. The driver will now see these other users since they will be right in front of the car, as opposed to possibly being in the driver’s blind spot when entering on an angle.
Motorists will only be restricted to this slower speed for at most a couple blocks before they can get back on the main road. Even during busy times of day, this service roads tend to be nearly car-free due to the limited need for people to drive on them (Fig. 5). The service roads in front of homes were even quieter since only those who live there need to drive there, making these streets feel more like a side street than a main road (Fig. 7).
Figure 7: A service road on Haagweg in front of homes looks and feels more like a side street than a main road. Meanwhile, the parallel through lanes carry a high traffic volume.
If the arterial road is congested, drivers might try to use the service road to pass the traffic. However, if this is allowed, it would defeat the function of this feature road. To avoid this activity, service roads must only be short segments that eventually force drivers back onto the main road. On Zuidpoldersingel (Fig. 8) and Haagweg (Fig. 9), the service roads turns into bike paths for short stretches. As a biker, I hardly noticed the shifts between service roads and biking infrastructure. This is because the width of the road did not change, but parking was taken away, sometimes to make room for a car right-turn lane on the main road. As a result, the bike path is wide enough for emergency vehicles to use it to pass traffic. In addition, emergency vehicles can drive on the tram tracks on Haagweg if needed since the tracks are below the road surface.
Figure 8 (left): A service roadon Zuidpoldersingel turns into a bike path for a short stretch and then back into a service road. This change to a bike road is indicated by red pavement and a blue “bikes and mopeds only” sign Motor vehicles are forced to exit the road before this point.
Figure 9 (right): The same changes to a service road on Haagweg are even more subtle. Notice the exit to the through lane provided for motor vehicles right before the bike path begins.
On Vrijenbanselaan, another strategy is used since the service road is shorter (Fig. 10). This service road mainly provides access to parking in a shopping area, so it ends when the shops end. It also makes a turn at the end of the block to follow the shops, rather than continuing straight. This geometry makes using this road as a through road impractical, if not impossible. At the end of the shopping area, a cycle track begins so that cyclists can still use the service road as their through road. In this case, the cycle track is not wide enough to hold emergency vehicles, but the main road has two lanes in each direction to solve this problem.
Figure 10: A service road on Vrijenbanselaan curves, forcing traffic to use the main road to continue straight. Cyclists have the option to cross the street and continue straight or turn with the service road. Motorists, on the other hand, cannot easily continue straight after entering the service road, as the exit is not until after the road turns.
This new design, although it removes one lane in each direction for through traffic, does not cause congestion. Activities such as pulling over and parking tend to cause congestion in the right lane of roads with two lanes. In these cases, the right lane is blocked, so only one lane is functional anyway. Now, these activities are moved to the service road, so through traffic can flow as desired. In addition, having left and right pocket turning lanes on the main road allows for through traffic to continue to flow, without needing a wide main road all the time. This is consistent with the Dutch principle of “skinny roads, wide nodes”. The road is usually skinny and has few lanes, but branches out at intersections to make turning easier. Having one clear through lane is better than two congested lanes.
Furthermore, it is often the traffic lights, not congestion, that cause delay in commutes. If cars have to stop at many lights, a commute will take a while regardless of the number of lanes. One way to reduce the number of lights is to reduce the number of intersections. On Haagweg, some of the right turns take place from the service road (Fig. 11), again allowing the main road to flow even when many people need to turn right.
Figure 11: A service road on Haagweg. Those who want to turn right onto the side street must do it from the service road. This is done to minimize turning traffic on the main road. Otherwise, a light might be needed at this intersection.
Both homes and shops are found on these three roadways, so many people choose to walk to the stores. In addition, thosewho drive may park on one side of the street and then need to cross to the other side. So, it is important to have streets that are safe and easy to cross. These service roads making living on a busy road less undesirable since there is a buffer between the homes and the main street (Fig. 12).
Figure 12: Homes on the Vrijenbanselaan service road. Vrijenbanselaan is a main throughway for driving between cities, but this service and the greenery creates some space between these residents and the busy road.
On a road with two lanes in each direction, pedestrians usually have to cross two, or even four lanes at a time. If the street has tram tracks like Haagweg, this makes crossing even more stressful. Service roads make crossing the street safer for pedestrians by limiting the number of lanes they need to cross at once. First, pedestrians never need to cross more than one lane of traffic at a time. After crossing the service road, there should be space to wait before crossing the main road. There should also be space to wait on the tram tracks before and after crossing them. Crossing the service road does not require a cross signal due to the low traffic volume. The main road may require a cross signal. The tram tracks should have across signal or an indicator when the tram is coming. Overall, it is quicker to cross streets with service roads since one lane can be crossed at a time rather than waiting for all lanes of traffic to stop at once. Along quieter stretches, cross signals may not be necessary for pedestrians since they can just want for a gap in traffic. This means fewer lights for cars and therefore less delay.
On all three roads, greenery is used to separate the main road from the service road. This is a simple way to make the service road feel calmer and isolated from busy through traffic, thus making the road feel safer for more vulnerable road users (Fig. 13).
Figure 13: Greenery along Haagweg is used to separate different parts of the road and make the road more visually appealing and feel safe.
Overall, service roads are a successful way to separate through and destination traffic, provide a safe area of the road for cyclists, and make crossing the street easier and safer. Boston could greatly benefit from this feature. One street that could use a service road is Huntington Avenue, particularly between Northeastern and Heath Street (Fig. 14). This roadway has two through lanes in each direction in most places as well as a tram running through the middle of the street. Both sides have street parking for those accessing home, work, school, and businesses. These features together cause a high congestion, fail to provide a safe place for cyclists, and make crossing the street difficult forpedestrians. The same is true for Tremont Street in the South End. Although a service road is present in one area, it could benefit from more stretches throughout the area. Tremont has several businesses and homes, but accessing them by bike or by foot could mean risking your life. So, adding service roads seems like an ideal way to solve these problems.
Figure 14: A visualization of what a service road would look like on Huntington Avenue, a road with two lanes in each direction in front of Northeastern University. This is an area that has had several traffic fatalities in the past few years. This design provides a safe area for cyclists and only makes pedestrians cross one lane of traffic at a time. The intersection shown is currently signalized, but this design may allow for those lights to be removed.