Lynchburg Urban Network Wiki

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======Street Lane Widths=====

This page attempts to lay out the various layers of standards, requirements, ordinances, etc. that lead street and road designs in [[city-of-lynchburg|Lynchburg, Virginia]] to use the lane widths that they do.

=====AASHTO=====

====A Policy on Geometric Design of Highways and Streets====

* 5.3 Local Streets in Urban Areas
        * 5.3.2.1 Width of Traveled Way
            * "Lanes for moving traffic preferably should be **10 to 11 ft [3.0 to 3.3 m]** wide, and in industrial areas they should be **12 ft [3.6 m]** wide. Where the available or attainable width of right-of-way imposes severe limitations, **9-ft [2.7-m]** lanes can be used in residential areas, and **11-ft [3.3-m]** lanes can be used in industrial areas. Added turning lanes where used at intersections should be at least **9 ft [2.7 m]** wide, and desirably **10 to 12 ft [3.0 to 3.6 m]** wide, depending on the percentage of trucks. Where bicycle facilities are included as part of the design, refer to the AASHTO //Guide for the Development of Bicycle Facilities// (6).
        * 5.3.2.2 Number of Lanes
            * "On residential streets where the primary function of the street is to provide access to adjacent development and foster a community environment, at least **one** unobstructed moving lane must be provided even when parking occurs on both sides. The level of user inconvenience occasioned by the lack of two moving lanes is remarkably low in areas where single-family units prevail. Local residential street patterns are such that travel distances are less than 0.5 mi [1 km] from the trip origin to a collector street. In multifamily-unit residential areas, a minimum of **two** moving traffic lanes to accommodate opposing traffic may be desirable. In many residential areas, a minimum roadway width of **26 ft [8 m]** is needed where on-street parking is permitted. This curb face-to-curb face width of **26 ft [8 m]** provides a **12 ft [3.6 m]** center travel lane that provides for the passage of fire trucks and two **7-ft [2.2-m]** parking lanes. Opposing conflicting traffic will yield and pause in the parking lane area until there is sufficient width to pass."
    * 6.3 Collectors in Urban Areas
        * 6.3.2.1 Width of Roadway
            * "The width of a collector street should be planned as the sum of the widths of the ultimate number of lanes for moving traffic, parking, and bicycles, including median where appropriate. Lanes within the traveled way should range in width from **10 to 12 ft [3.0 to 3.6 m]**. In industrial areas, lanes may be **12 ft [3.6 m]** wide except where lack of space for right-of-way imposes severe limitations; in such cases, lane widths of **11 ft [3.3 m]** may be used. Added turning lanes at intersections, where used, should range in width from **10 to 12 ft [3.0 to 3.6 m]**, depending on the volume of trucks. Where shoulders are provided, roadway widths in accordance with table 6-5 should be considered. Additional guidance on the width of roadways used by transit vehicles can be found in the AASHTO //Guide for Geometric Design of Transit Facilities on Highways and Streets (8)//."
        * 6.3.2.2 Number of Lanes
            * "**Two** traffic lanes are sufficient for most collector streets. In some instances, in commercial areas where there are intersection and midblock left turns, it may be advantageous to provide additional left-turn lanes or **a** continuous two-way left-turn lane in the center of the roadway. Bicycle lanes are often provided on collector streets to create continuous bicycle networks in the community. The number of lanes to be provided on collector streets with high traffic volumes should be determined from a capacity analysis. This analysis should consider anticipated transportation modes, and both intersections and midblock locations in assessing the ability of a proposed design to provide the desired level of service for all users. Such analyses should be made for the future design year traffic volume by using the procedures in the most recent edition of the //Highway Capacity Manual (19)// or other appropriate traffic analysis tools. For further information, see Section 2.4, "Highway Capacity," and the FHWA //Traffic Analysis Tools// website //(11)//,"
    * 7.3 Arterials in Urban Areas
        * 7.3.3.2 Lane Widths
            * "Lane widths on through travel lanes may vary from **10 to 12 ft [3.0 to 3.6 m]**. Lane widths of **10 ft [3.0]** may be used in more constrained areas where truck and bus volumes are relatively low and speeds are less than 35 mph [60 km/h]. Lane widths of **11 ft [3.3 m]** are used quite extensively for urban arterial street designs. The **12-ft [3.6-m]** lane widths are desirable, where practical, on high-speed, free flowing, principal arterials."
        * 7.3.3.4 Number of Lanes
            * "The number of lanes varies, depending on traffic demand, presence and needs of other users, and availability of the right-of-way, bu the typical range for arterials in urban areas is **four to eight** through lanes in both directions of travel combined. Many minor arterials may have **two** through-travel lanes, **one** in each direction. A capacity analysis for all users should be performed to determine the proper number of lanes in consideration of the space needed to accommodate all users of the right-of-way. In addition, roadways are sometimes widened through intersections by the addition of **one or two** auxiliary lanes to accommodate turning vehicles. Section 2.4 presents additional information on capacity analysis."

=====NACTO=====

====Urban Street Design Guide====

* Lane Width
        * " Lane widths of **10 feet** are appropriate in urban areas and have a positive impact on a street's safety without impacting traffic operations. For designated truck or transit routes, one travel lane of **11 feet** may be used in each direction. In select cases, narrower travel lanes (9–9.5 feet) can be effective as through lanes in conjunction with a turn lane."

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