Mar 242013

Nov. 30 2014 update:  Modest changes were made to the Road Code by Montgomery County Bill 33-13, passed by the County Council on Nov. 25, 2014.  Most of the Road Code is unchanged.

The Montgomery County “Road Code” is the set of standards that governs every aspect of road design on county roads, including the widths of things like travel lanes, bike lanes and sidewalk buffers; the design of stormwater management; and less interesting things like curb height.  This matters a lot to cyclists.  Officially called the Context Sensitive Road Design Standards, the Road Code is actually a set of county regulations.  It can be viewed in PDF form (in the relevant County Council resolution) or viewed online (go to Chapter 49 of the code called COMCOR).  I’ve broken it up into convenient PDF files below.

The county has defined fourteen or more street types.  It’s also defined three area types (land use types) which are urban, suburban and rural.   Street type, area type, total right-of-way width and presence of features like parking or bike lanes determine the recommended widths of each part of the street.  There are 64 resulting “templates” representing different combinations of these factors, which engineers can apply to streets in the county.

The templates are meant only as guides, however, and it’s expected that they’ll be tailored based on available right-of-way and other factors.  The text portion of the Road Code provides much additional information including general guidelines for each element (including preferred width of bike lanes), desired target speeds, tree placement, and stormwater management standards among other things.  The text portion indicates preferred widths that are often greater than what the templates specify.  For example, most templates for arterial streets call for 14′ outside lanes, whereas the text states that 14.5′ “may be appropriate”.  So planners and engineers have options.  In practice though, it seems that road designers go by the templates more than the text.  There is a great deal of difference between 14′ and 14.5′ to a cyclist, but designers are under pressure to choose the smaller value.

I have diagrams for all the templates but didn’t scan them all in.  Here’s an example:

Urban arterial with 4 lanes and bike lanes (elements with no dimension specified are omitted from the template)

Here are the 64 templates used in the Road Code, digitized from the official version (or you can see the whole set at once):

Where next to a curb, a lane’s width is measured from the vertical part of the curb to the midpoint of the lane line, i.e. it includes the concrete gutter if present.

There is certainly room for improvement in the Road Code.  Most problematic is the fact that none of the business district street templates provide any space for bikes (see below).  Bike space is also lacking for secondary streets, tertiary streets and country roads, though these are often minor streets (industrial streets have wide outside lanes).  One of the templates for primary streets has a door zone problem.

Street Types

Below are the street types defined in the Road Code.  To get a rough idea of what they mean, see this unofficial map (though it doesn’t distinguish between arterials and minor arterials). The following text, abridged and with my own additions in italics, comes from the Road Code:

  • FREEWAY – A road meant exclusively for the through movement of vehicles at a high speed. Access must be limited to grade-separated interchanges. (I-270, I-495)
  • CONTROLLED MAJOR HIGHWAY – A road meant exclusively for the through movement of vehicles at lower speeds than a Freeway. Access must be limited to grade-separated interchanges or at grade intersections with public roads. (Great Seneca Highway, Rt. 29 north of New Hampshire Ave)
  • MAJOR HIGHWAY – A road meant exclusively for the through movement of vehicles at a moderate speed. Access must be primarily from grade-separated interchanges and at grade intersections with public roads, although driveway access is acceptable in urban and denser suburban settings. (most of Connecticut Ave, Veirs Mill Rd, Georgia Ave, Old Georgetown Rd)
  • ARTERIAL – A road meant primarily for the through movement of vehicles at a moderate speed, although some access to abutting property is expected. (Woodmont Ave, Parklawn Drive, Muncaster Mill Rd, Fairland Rd, Arcola Ave, Wayne Ave)
  • MINOR ARTERIAL – A Minor Arterial is a two-lane Arterial meant nearly equally for through movement of vehicles and access to abutting property. (New designation)
  • PRIMARY RESIDENTIAL STREET – A road meant primarily for circulation in residential zones, although some through traffic is expected. (Tilden Lane, Greentree Rd, Notley Rd, Jones Mill Rd, Brookville Rd in Chevy Chase, Franklin Ave)
  • BUSINESS DISTRICT STREET (or BUSINESS STREET for short) – A road meant for circulation in commercial and mixed-use zones (equivalent to a primary street in a business district). (Bethesda Ave, Marinelli Rd, Amherst Ave, Cameron St)
  • PRINCIPAL SECONDARY RESIDENTIAL STREET – A Secondary Residential Street meant to carry somewhat more through traffic.
  • SECONDARY RESIDENTIAL STREET – A road meant nearly exclusively for access to abutting properties in residential zones. A road meant to provide access between a residential development with fewer than 200 dwelling units and one or more higher classification roads.
  • TERTIARY RESIDENTIAL STREET – A road meant (exclusively for access to abutting property in residential zones) to provide direct access to a residential development with 75 or fewer dwelling units.

Here are the less common street types:

  • PARKWAY – A road meant exclusively for the through movement of vehicles at a moderate speed. Access must be limited to grade-separated interchanges and at-grade intersections. Any truck with more than four wheels must not use a Parkway.  (Montrose Parkway)
  • INDUSTRIAL STREET – A road meant for circulation in industrial zones (equivalent to a primary street in an industrial zone; seemingly inaccurately called “industrial street/office park street” in template tables).
  • COUNTRY ARTERIAL – A Country Arterial is an Arterial that is typically in the County’s agricultural reserve. (Partnership Rd, Whites Ferry Rd east of Poolesville, Sundown Rd east of Laytonsville)
  • COUNTRY ROAD – A Country Road has the function of a Primary Residential Street, typically in the County’s agricultural reserve. (Additionally, the county may designate rural roads as “rustic” or “execeptional rustic” to limit improvements).

Land Use Types (Area Types)

The Road Code defines three area types:

  • URBAN – Includes central business districts, town centers, and dense commercial areas.  The county decides where they are.
  • SUBURBAN – Vary widely in character.
  • RURAL – Pretty easy to identify.

As described above, the street type of a road and the area type of its locale determines the templates that apply to it.

Business District Streets

There are four templates for business district street (aka business street).  None of these call for bike lanes or wide outside lanes, so it’s important for planners to look beyond the templates when it comes to these streets.  Business streets are highly useful for cyclists, since 1) they are not as fast as arterials, but 2) they are more direct and convenient than lesser streets, and 3) many destinations are located along them.  Furthermore, business streets are common in plans for town centers, urban districts and mixed use areas, which are prime areas for bike transportation.   Every business street should either be very slow (slow enough for cyclists to be comfortable “taking the lane”) or have some provision for cars and bikes operating side by side (bike lanes, wide lanes, or in some cases just extra lanes). When the Road Code is amended at some point in the future, templates for business streets with bike lanes should be added.

Here are visual depictions of the four business street templates.  Elements with no dimension specified are omitted from the template.

Business street – parking on one side

Business street – parking on both sides

Business street – 4 lanes, parking on both sides

Business street with median


In 2007, the County Council sought to change county road standards in order to reduce traffic speeds and foster a more pedestrian-friendly street environment, particularly in urban areas.  Many desired an approach of narrowing streets to calm traffic and provide more space beyond the curbs, while bicyclists were concerned that narrowing roads might become the default solution.  At the same time, environmental stakeholders wanted to incorporate new stormwater management techniques to reduce stormwater runoff into sewers and streams.  So with urging from bike advocates and water quality advocates and others, the council established a work group of 20+ stakeholders to create the new standards by consensus.   I represented bicyclists on the work group, while other group members came from organizations as varied as the Coalition for Smarter Growth, AAA and WMATA.  Government members on the work group represented DOT, the Planning Department, Montgomery County Public Schools, MCFD, MCPD and various other agencies.  Over several months the work group discussed the issues and hammered out details until they’d crafted a new draft set of design standards.  The county adopted the standards with a few tweaks, creating the Road Code that’s in effect today.

The resulting standards were generally a compromise.  The recommended bike lane widths are acceptable (mostly without door zone issues).  Most street types in the guide have bike lanes as an option (except for one key type).  Wide outside lanes are recommended on fast roads, though the stipulated width is less than what’s desired.  Wide outside lanes on slower city streets are generally a thing of the past.

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