Edge lane roads (ELRs)—also known as an advisory bike lane or advisory shoulder 1—is a road structure that accommodates two-way motor vehicle and vulnerable road user traffic by utilizing a central travel lane and edge lanes. The center lane is designated for and shared by cars heading in both directions. Vulnerable road users have the right of way in the edge lanes; however, moving vehicles may enter the edge lanes to pass vulnerable road users after yielding to approaching moving vehicles.2 The car lane lacks a center line and is often broader than usual but not big enough to accommodate two vehicles. Instead, when vehicles meet, they temporarily occupy one of the edge lanes to negotiate space. ELRs are particularly beneficial on narrow roads for regular bike lanes or sidewalks. These affordable solutions have the potential to enhance the safety of the most vulnerable road users, therefore decreasing collisions and enhancing the nation’s transportation system.3
How it Helps
By constructing broad shoulders on millions of miles of low-volume, high-speed rural highways, ELRs may lower the incidence of single-vehicle incidents involving roadway departure. This is a high-priority approach due to ELRs’ capacity to affordably offer facilities for vulnerable road users, its potential to save lives on rural roads, and the possibility of broad, quick adoption by transit agencies and local governments.2
Implementing
Design:
The recommended width for edge lanes is 1.5 meters, inclusive of a 0.3-meter solid edge line. If adequate space is available, it may be preferable to create a bicycle lane. In rural locations, the minimal guideline width should be 0.9 meters, inclusive of the edge line. Due to the narrowness of the edge lane, there should be no gullies.4 Most ELRs are constructed on two-lane roadways that have been upgraded to four lanes. Two-lane roads have different viewing distance requirements than single-lane roads. Sight distance restrictions are crucial on ELRs when visual impediments and vertical or horizontal curves prohibit drivers from seeing oncoming traffic.5
Edge Lane Markings:
ELR markings should emphasize division and be distinct from typical vehicle lane delineation to aid new drivers in understanding the street’s intended use. Considering that certain motorists may be inexperienced with this feature, it is crucial to indicate the intended usage of the edge lanes using bicycle or pedestrian markings. Additional signage may be required if these indicators are likely to be concealed by snow. The lines delineating the central traffic lane from the outer lanes should be white and of sufficient width—minimum width of 8 inches, with 3-foot stripes and 4-foot gaps. Usage of regular bike lane markings inside the edge lanes is advised to prevent misunderstanding among inexperienced riders and reinforce the intended use of the lanes.
Challenges:
However, there are certain challenges associated with the construction of ELRs. For example, edge lane markings may result in increased driving speeds. Further, edge and cycle lanes do not generally contribute to the reduction of the number of left turning accidents.4
Examples
1) California Bicycle Coalition (CalBike)
CalBike is an advocacy organization that supports egalitarian, welcoming, and thriving communities where biking makes it possible for all Californians to enjoy healthy lifestyles. CalBike has created financing schemes to improve and broaden complete street rules. They also provide funding for infrastructure for cycling and walking. CalBike is attempting to provide traffic engineers tools, such as edge lane roadways, to provide cyclists with a safe zone to ride on curvy roadways.
2) Mineta Transportation Institute (MTI)
Mineta Transportation Institute (MTI) strives to promote the mobility of vulnerable road users by enhancing the security, effectiveness, accessibility, and comfort of the country’s transportation infrastructure. MTI is involved in research, education, workforce development, and technology transfer, while offerings thorough assessments of edge lane roads’ safety.
1. Mineta Transportation Institute. (2021). Safety considerations for all road users on edge lane roads. [cited 2022 Jun 30]. Available from: https://transweb.sjsu.edu/research/1925-Safety-Edge-Lane-Roads
2. Transportation Research Information Services (TRIS). [cited 2022 Jun 30]. Available from: https://rns.trb.org/details/dproject.aspx?n=43240
3. Mineta Transportation Institute. (2021). Edging in safer roads for all transportation modes. [cited 2022 Jun 30]. Available from: https://transweb.sjsu.edu/press/Edging-Safer-Roads-All-Transportation-Modes
4. Cycling Embassy of Denmark. (2019). Edge lanes. [cited 2022 Jun 30]. Available from: https://cyclingsolutions.info/edge-lanes/
5. Williams, M. (2020). Edge Lane Road Design Guide. Advisory Bike Lanes. [cited 2022 Jun 30]. Available from: https://www.advisorybikelanes.com/uploads/1/0/5/7/105743465/2020-02-11_edge_lane_road_design_guide.pdf