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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

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:

____________________________ ____________________________

____________________________

A-1

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.

A-2

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

, 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.

See check dam installation specifications.

A-3

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.

A-4

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)

inimum Diameter

for

Culverts on

Intermittent Streams

(inches)

16 24

20 30

40 36

50 42

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

B-1

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