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TOWN ROAD AND BRIDGE STANDARDS
(June 5, 2019)
MUNICIPALITY OF ____________________, VERMONT
The Legislative Body of the Municipality of ______________________ hereby adopts the following Town Road and Bridge Standards
which shall apply to the construction, repair, and maintenance of town roads and bridges.
The standards below are considered minimums. Municipalities that have construction standards / specifications in place that meet
or exceed the minimum standards: indicate adoption date and include as Appendix C. Date of Adoption: ______________
Municipalities must comply with all applicable state and federal approvals, permits and duly adopted standards when undertaking
road and bridge activities and projects.
Any new road regulated by and/or to be conveyed to the municipality shall be constructed according to the minimum of these
standards.
Circle YES or NO below to indicate town adoption of that section of the Standards
Road and Bridge Standards Sections
Hydrologically-connected road
segments*
Non-hydrologically-connected road
segments**
Section 1 Municipal Road Standards
YES (Required by Act 64)
YES NO
Section 2 Class 4 Road Standards
YES (Required by Act 64)
YES NO
Town wide
Section 3 - Perennial stream- bridge and
culvert standards
YES (Required by DEC Stream Alteration Standard)
Section 4 Intermittent stream crossings
YES NO
Section 5 - Roadway construction standards
YES NO
Section 6 - Guardrail standard
YES NO
Section 7 - Driveway access standard
YES NO
Road segments ANR Resources Atlas includes a map layer of all of Vermont’s municipal roads divided into 100-meter (328 foot)
segments, each with a unique identification number.
*Hydrologically-connected road segments - are those municipal road segments and catch basin outlets, Class 1-4, as shown on the
ANR Natural Resources Hydrologically-connected municipal road segment layer (http://anrmaps.vermont.gov/websites/anra5/ ) or
the Road Erosion Inventory Scoring (MRGP Implementation Table portal) layer
(https://anrweb.vt.gov/DEC/IWIS/MRGPReportViewer.aspx?ViewParms=True&Report=Portal).
**Adoption of standards on non-hydrologically-connected road segments does not indicate that these road segments are then
subject to the Municipal Roads General Permit (MRGP).
Municipalities may also find additional resources in the latest version of the Vermont Better Roads Manual.
https://vtrans.vermont.gov/sites/aot/files/highway/documents/ltf/Better%20Roads%20Manual%20Final%202019.pdf
Road and Bridge Standards Sections
Section 1 Municipal Road Standards - See Appendix A
These standards are required by Act 64 and the DEC Municipal Roads General Permit (MRGP) for hydrologically-connected roads
only.
Municipalities may adopt Section 1 Road standards by road type for non-hydrologically-connected roads/segments/catch basins.
Section 2 Class 4 Road Standards - See Appendix A
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Section 3 - Perennial stream - bridge and culvert standards
Bridge and culvert work on perennial stream crossings must conform with the statewide DEC Stream Alteration Standard.
“Perennial stream” means a watercourse or portion, segment, or reach of a watercourse, generally exceeding 0.25 square miles in
watershed size, in which surface flows are not frequently or consistently interrupted during normal seasonal low flow
periods. Perennial streams that begin flowing subsurface during low flow periods, due to natural geologic conditions, remain
defined as perennial. All other streams, or stream segments of significant length, shall be termed intermittent. A perennial stream
shall not include the standing waters in wetlands, lakes, and ponds.
Streambank stabilization and other in-stream work must conform with the statewide DEC Stream Alteration Standard.
For River Management Engineer Districts: https://dec.vermont.gov/sites/dec/files/wsm/rivers/docs/RME_districts.pdf
Section 4 Intermittent stream crossings See Appendix B for sizing table and graphic. These standards are above and beyond the
culvert standards in Section 1.
“Intermittent streams” are defined as streams with beds of bare earthen material that run during seasonal high flows but are
disconnected from the annual mean groundwater level.
Section 5 - Roadway construction standards Sub-base and gravel standards
All new or substantially reconstructed gravel roads shall have inches* thick gravel sub-base, with an additional inches* top
course of crushed gravel.
All new or substantially reconstructed paved roads shall have inches* thick gravel sub-base.
*Municipalities shall indicate their own construction criteria.
Section 6 - Guardrail standard
When a roadway, culvert, bridge, or retaining wall construction or reconstruction project results in hazards such as foreslopes, drop
offs, or fixed obstacles within the designated clear-zone, the AASHTO Roadside Design Guide will govern the analysis of the hazard
and the subsequent treatment of that hazard. For roadway situations, an approved barrier system may be steel beam guardrail
with 6-foot posts and approved guardrail end treatment. If there is less than 3 feet from the rail to the hazard, then steel beam
guardrail with 8-foot posts shall be used. The G-1D is an example of an approved guardrail end treatment. For bridge rails systems,
VTrans bridge rail standards shall be referenced
Section 7 - Driveway access standard
The municipality has a process in place, formal or informal, to review all new drive accesses and development roads where they
intersect town roads, as authorized under 19 V.S.A. Section 1111. Municipality may reference Vtrans Standard A-76 Standards for
Town & Development Roads and B-71 Standards for Residential and Commercial Drives; the Vtrans Access Management Program
Guidelines; and the latest version of the Vermont Better Roads Manual for other design standards and specifications.
Passed and adopted by the Legislative Body of the Municipality of _____________________________, State of Vermont on
_________________________, 20___
Selectboard / City Council / Village Board of Trustees:
____________________________ ____________________________
____________________________ ____________________________
____________________________
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Appendix A
Section 1: MUNICIPAL ROAD STANDARDS
The following standards constitute the minimum required Best Management Practices (BMPs) for municipal roads. These
standards shall apply to the construction, repair, and maintenance of all town roads and bridges.
It is the municipality’s responsibility to maintain all practices after installation. Roads not meeting these standards must
implement the BMPs listed below in order to meet the required town’s standards.
Feasibility
Municipalities shall implement these standards to the extent feasible. In determining feasibility, municipalities may
consider the following criteria: The implementation of a standard listed in of this documentation does not require the
acquisition of additional state of federal permits or noncompliance with such permits, or noncompliance with any other
state or federal law. The implementation of a standard does not require the condemnation of private property; impacts
to significant environmental and historic resources, including historic stone walls, historic structures, historic landscapes,
or vegetation within 250 feet of a lakeshore; impacts to buried utilities; and excessive hydraulic hammering of ledge.
Standards for All Construction and Soil Disturbing Activities
Following construction and soil disturbance on a road, all bare or unvegetated areas shall be revegetated with see and
mulch, hydroseeded, or stone lined within 5 days of disturbance of soils, or, if precipitations is forecast, sooner.
Standards for Gravel and Paved Roads with Ditches
Baseline Standards for Gravel and Paved Roads with Ditches
The following are the standards for all gravel and paved municipal roads with drainage ditches, whether or not erosion is
present. These standards also apply to all new construction and significant upgrades of stormwater treatment practices.
A. Roadway/Travel Lane Standards
1. Roadway Crown
a. Gravel roads shall be crowned, in or out-sloped:
Minimum: ¼ inch per foot
Recommended: ¼ inch to ½ inch per foot or 2% - 4%
b. Paved/ditched roads shall be crowned during new construction,
redevelopment, or repaving where repaving involves removal of the existing paving.
Minimum: 1/8 inch per foot or 1%
Recommended: 1% - 2%
2. Shoulder berms (also called Grader/Plow Berm/Windrows)
Shoulder berms shall be removed to allow precipitation to shed from the travel lane into the road
drainage system. Roadway runoff shall flow in a distributed manner to the drainage ditch or filter area
and there shall be no shoulder berms or evidence of a “secondary ditch”. Shoulder berms may remain
in place if the road crown is in-sloped or out-sloped to the opposite side of the road from berm side of
road. The shoulder berm standard only applies to gravel roads with drainage ditches.
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B. Road Drainage Standards
Roadway runoff shall flow in a distributed manner to grass or a forested area by lowering road shoulders or
conversely by elevating the travel lane level above the shoulder. Road shoulders shall be lower than travel lane
elevation. If distributed flow is not possible, roadway runoff may enter a drainage ditch, stabilized as follows:
1. For roads with slopes between 0% and 5%: At a minimum, grass-lined ditch, no bare soil. Geotextile
and erosion matting may be used instead of seed and mulch. Alternatively, ditches may be stabilized
using any of the practices identified for roads with slopes 5% or greater included in subpart B.2 below.
Recommended shape: trapezoidal or parabolic cross section with mild side slopes; 2 foot horizontal per
1 foot vertical or flatter and 2-foot ditch depth.
2. For roads with slopes 5% or greater but less than 8%:
a. Stone-lined ditch: minimum 6 to 8-inch minus stone or the equivalent for new practice
construction. Recommended 2-foot ditch depth from top of stone-lined bottom,
b. Grass-lined ditch with stone check dams
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, or
c. Grass-lined ditch if installed with disconnection practices such as cross culverts and/or turnouts
to reduce road stormwater runoff volume. There shall be at least two cross culverts or
turnouts per segment disconnecting road stormwater out of the road drainage network into
vegetated areas or spaced every 160 feet.
3. For roads with slopes of 8% or greater: Stone-lined ditch.
a. For slopes greater than or equal to 8% but less than 10%:
minimum 6 to 8-inch minus stone or the equivalent for new
construction. Recommended 2-foot ditch depth from top of stone-
lined bottom.
b. For slopes greater than 10%: minimum 6 to 8-inch minus stone. Recommended 12-inch minus
stone or the equivalent. Recommended
2-foot ditch depth from top of stone-lined bottom.
4. If appropriate, bioretention areas, level spreaders, armored shoulders, and sub-surface drainage
practices may be substituted for the above road drainage standards.
C. Drainage Outlets to Waters & Turnouts
Roadway drainage shall be disconnected from waterbodies and defined channels, since the latter can act as a
stormwater conveyance, and roadway drainage shall flow in a distributed manner to a grass or forested filter
area. Drainage outlets and conveyance areas shall be stabilized as follows:
1. Turn-outs all drainage ditches shall be turned out to avoid direct outlet to surface waters.
2. There must be adequate outlet protection at the end of the turnout, based upon slope ranges below.
Turnout slopes shall be measured on the bank where the practice is located and not based on the road
slope.
a. For turnouts with slopes of 0% or greater but less than 5%: stabilize with grass at minimum.
Alternatively, stabilize using the practices identified in subpart b c below, when possible.
b. For turnouts with slopes 5% or greater: stabilize with stone.
c. For slopes greater than 5% but less than 10%: minimum 6-inch to 8-inch minus stone or the
equivalent for new construction.
d. For slopes greater than 10%: minimum 6 to 8-inch minus stone or equivalent for new
construction. Recommend 12-inch minus stone or the equivalent.
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See check dam installation specifications.
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Drainage and Intermittent Stream Culvert Standards
The following are the required culvert standards for all gravel and paved roads with ditches where rill or gully erosion is
present. These standards also apply to new construction and significant upgrades of stormwater treatment practices.
1. Municipal Culverts (Drainage and Intermittent Streams)
1. Culvert end treatment or headwall required for areas with road slopes 5% or greater if erosion is due to
absence of these structures. End treatment or headwall is required for new construction on slopes 5%
or greater.
2. Stabilize outlet such that there will be no scour erosion, if erosion is due to absence or inadequacy of
outlet stabilization. Stone aprons or plunge pools required for new construction on road slopes 5% or
greater.
3. Upgrade to 18-inch culvert (minimum), if erosion is due to inadequate size or absence of structure.
4. A French Drain (also called an Underdrain) or French Mattress (also called a Rock Sandwich) sub-surface
drainage practice may be substituted for a cross culvert.
2. Driveway Culverts within the municipal ROW
1. Culvert end treatment or headwall required for areas with road slopes of 5% or greater, if erosion is due
to absence of these structures. End treatment or headwall is required for new construction.
2. Stabilize outlet such that there will be no scour erosion, if erosion is due to absence or inadequacy of
outlet stabilization. Stone aprons or plunge pools required for new construction.
3. Upgrade to minimum 15-inch culvert, 18-inch recommended, if erosion is due to inadequate size or
absence of structure.
Standards for Paved Roads with Catch Basins
Catch Basin Outlet Stabilization: All catch basin outlets shall be stabilized to eliminate all rill and gully erosion. Catch
basin outfall stabilization practices include: stone-lined ditch, stone apron, check dams and culvert header/headwall.
Stone Check Dam Specification
Height: No greater than 2 feet. Center of dam should be 9 inches lower than the side elevation
Side slopes: 2:1 or flatter
Stone size: Use a mixture of 2 to 9-inch stone
Width: Dams should span the width of the channel and extend up the sides of the banks
Spacing: Space the dams so that the bottom (toe) of the upstream dam is at the elevation of the top (crest) of the
downstream dam. This spacing is equal to the height of the check dam divided by the channel slope.
Spacing (in feet) = Height of check dam (in feet)
Slope in channel (ft/ft)
Maintenance: Remove sediment accumulated behind the dam as needed to allow channel to drain through the stone
check dam and prevent large flows from carrying sediment over the dam. If significant erosion occurs between check
dams, a liner of stone should be installed.
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Check Dam Specification:
Section 2: STANDARDS FOR CLASS 4 ROADS
Stabilize any areas of gully erosion with the practices described above or equivalent practices. Disconnection practices
such as broad-based dips and water bars may replace cross culverts and turnouts.
Appendix B
Active Channel Culvert Sizing for Intermittent Stream Crossings
Choose the drainage area closest to your crossing site drainage area
Drainage Area
(Acres)
M
inimum Diameter
for
Culverts on
Intermittent Streams
(inches)
4
15
8
18
16 24
20 30
40 36
50 42
80
48
120 60
160 66
200
Streams with drainage areas of 160
acres or greater are likely to be
perennial. Adhere to the VTDEC
Technical Guidance for Identification of
Perennial Streams
320
350
450
640
Active Channel Width means the limits of the streambed scour formed by prevailing
stream discharges, measured perpendicular to streamflow. The active channel is
narrower than the bankfull width (approximately 75%) and is defined by the break in
bank slope and typically extends to the edge of permanent vegetation.
Culvert sizing for crossings on intermittent streams: Determine the Active Channel
Width by field measurements, the culvert size should meet or exceed the Active
Channel Width. To obtain the measurements go to the crossing location and obtain
several upstream Active Channel Width measurements in riffle (fast moving water)
narrower channel locations. The selected channel width should be a representative
average of the field measurements. In the absence of field measurements, the
drainage areas in the table can be used.
Active Channel Width
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