Learning the language of those responsible for our roads is particularly important for community members. Every profession has its acronyms and technical phrases and even though we all use the results of their work every day, we don’t necessarily understand the language of road design and construction.
Travel Lanes – This is the portion of the road provided for the movement of vehicles. The number of lanes is usually determined by the expected volume of traffic and the level of service to be provided. The width of a travel lane ranges between ten and twelve feet with the lanes becoming wider as the allowed speed or percentage of trucks increases. Generally, ten foot lanes are acceptable on low speed roads, and eleven foot lanes are acceptable in urban areas where right-of-way is tight and development is extensive. Outside travel lanes 16 feet wide must be considered if there is significant existing or proposed bicycle traffic in the area.
Medians – Medians are used to separate opposing traffic flows, allow space for speed changes and left-turning vehicles, minimize headlight glare, offer a refuge for pedestrians at intersections, provide width for future lanes, provide space for landscape planting, and provide space for barriers. A desirable minimum width for raised medians is six feet.
Shoulders – The treatment of shoulders affects safety, capacity, the surrounding environment, and both the initial cost and continuing maintenance costs of the road. These factors must be balanced. For example, the absence of a shoulder can result in a reduction in traffic speed and allow for sidewalks. On the other hand, shoulders can provide overflow parking, an emergency “break down” area, and access for bikers.
Clear Zones – This is the unobstructed, relatively flat area provided beyond the edge of the travel way for the recovery of errant vehicles. In other words, if the driver makes a mistake, this is the recovery zone. In downtown areas, the space for clear zones is typically not available, but on the approaches to downtown where speeds are higher, recovery areas may be important. They are not appropriate where the streets are curbed.
Curbs – Two types are available: mountable and barrier (non-mountable). They are useful in drainage control, right-of-way delineation, reduction of maintenance, and separating sidewalks from the roadway. Barrier curbs are typically required in areas with the potential for high speed or with structures close behind the curb.
Sidewalks – There are basically two placement options: flush with the roadside edge (if a curb is provided) or next to a buffer area, such as a planted or paved strip, located between the sidewalk and roadside. The pros and cons of each placement should be discussed. With buffer areas, pedestrians are kept further from moving vehicles, spaces are available for planting and the reduction of hard surfaces, and storage space is provided for snow removal, utility poles, signs, fire hydrants, and mail boxes. On the other hand, if parking is wed, the cars themselves provide a safety buffer and an additional area may not be desirable. The buffers require additional right-of-way that may be difficult or costly to provide. Finally, buffers used as planting strips require continuing maintenance expense. All sidewalks, no matter their placement, must comply with the Americans with Disabilities Act Accessibility Guidelines.
Bicycle Accommodation – There are five types of facilities:
Landscaping – Vegetation is a key element in and along the roadway and its application is almost limitless. It can aid safety by defining the road edge and slowing traffic, “soften” the hard surfaces needed, add beauty and interest for all users, and, above all, it can help a roadway achieve a better fit with its surroundings. Removing vegetation is often an emotional issue for communities. Alternatives such as traffic barriers, lowering speeds, or designs that incorporate the existing vegetation must be considered. The cost of continuing maintenance and who will be responsible is also an issue that must be considered.
Overhead Utilities – Utility poles along the roadway are often a safety hazard and almost always unsightly. The best, but most expensive solution, is to bury all the lines. Short of this, individual poles may be moved to eliminate interference with the road or sidewalk, the lines may be relocated to another right-of-way (behind roadside buildings, for example), the pole spacing may be increased, or multiple utilities may be combined on a single set of poles.
All of these options are complicated, expensive, and time consuming but often a very high priority in communities. SHA policy on funding of utility relocation should be discussed early in the process.
Source: When Main Street is a State Highway: Blending Function, Beauty and Identity
Published: 2002
