Overview - Minnesota LTAP€¦ · 1 Section 5 Construction Considerations Fall, 2017 Ann Johnson,...

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Section 5

Construction Considerations

Fall, 2017

Ann Johnson, PE Services

Brady Rutman, SRF Consulting Group

Construction Overview

Overview

• Pedestrian Curb Ramp Construction– Standard Plans

– Grade Breaks

– Landings

– Removals

– Curb & Gutter

– Detectable Warnings

– Finishing

– Roundabouts and Median Islands

• Driveway and Sidewalk Construction

– Doorway Landings

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Curb Ramp Construction

Standard Plans Legend

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Standard Plans

Indicates pedestrian ramp slope shall be between

5% minimum and 8.3% maximum in the direction

shown and the cross slope shall not exceed 2%.

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S

Landing

S

S

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Standard Plans Indicates pedestrian ramp slopes shall be greater

than 2% and less than 5% in the direction shown

and cross slope shall not exceed 2%.

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F

Landing

S

S

F F


Grade Breaks:

• Specifications for Construction 2521.3D2

• Provide vertical and straight joints parallel with or at right angles to the walk centerline

• Align joints with joints in adjoining work when possible

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Grade Breaks

• All grade breaks within the PAR shall be perpendicular to the path of travel ( See Notes Standard Plans sheets 1 & 2).

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Landing Construction• Standard Plans Sheets 1&2

• To ensure initial ramps and initial landings are properly

constructed, landings shall be cast separately

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3


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Landing Construction• Follow sidewalk reinforcement detail


Landing Construction:

• Fan Ramp: Separate Landing with sidewalk reinforcement

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• Table curb if necessary. Determine controlling elevation (usually lowest elevation) and set at 7%.

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7%


Special Provisions Prosecution of Work (1803)

3) After the curb has been correctly poured, the Contractor has set the

sidewalk forms, and prior to placing the concrete curb ramps/sidewalks,

the Contractor shall verify the requirements in S-1.1B will be achieved.

In addition, the longitudinal slopes shown in the Construction Plans

and the Standard Plans shall be utilized unless these conditions cannot

be met. The starting point for setting the forms on the controlling ramp

leg should be the following:

Steep (S) = 7%

Flat (F) = 4%

Landing = 1.5%

Sidewalk Cross Slope = 1.5%

Fan ramp = 4%

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4


• Verify ramp length, landing dimensions, push button location, and perpendicular grade breaks.

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7%

Landing


• Verify landing is connected to the PAR with perpendicular grade breaks.

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7%

Landing


• Establish both landings with perpendicular grade breaks, verify second ramp is between 2% and 5%.

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7%

Landing

2-5%(F)

Landing

(F)

(S)


• Whenever possible set grades to work within concrete

finishing tolerances.

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7%

1%4%

1.4%

5


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(S)

(F)

(F)(S)

4” curb

• Use Steep and Flat slopes to help match into surrounding topography and maintain positive boulevard drainage.


• When placing curb, check the plan for secondary landings

and adjust top of curb to match landing grades.

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(S)


• When placing curb, check for doorways, steps, bus stops, or

any other features that requires a landing at the back of curb

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Ramp Gutter Flow lines

Min. 0.5% Min. positive flow

Max. 2.0% Max. 2%

Preferred 1% Preferred 1%

ADA Preferred Construction Cross Slopes

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V-Curb• Note (3): Edge between new v-curb and in-place structure

shall be sealed and bond breaker shall be used between

existing structure and placed v-curb.

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Removal Limits

• The contractor shall use the appropriate ramp details in the plan and identify the removal limits for sidewalk and curb and gutter.

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Removal Limits

• If the Contractor determines the removal limits are not adequate to meet PROWAG / MnDOT specifications the Contractor shall stop work on that quadrant immediately and consult the Engineer.

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Removal Limits

• Landings required if the approaching sidewalk is inverse grade, also avoid “Tenting” of sidewalk.

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7


Removal Limits• The transition panels cross slope corrections should be 1 linear Ft. of

sidewalk per 0.5% per of cross slope. When PAR width is greater than 6’ or over 5% running slope double the calculated transition length.

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Example: A transition panel from in place sidewalk with 4.5% cross slope, to new sidewalk at 1.5% cross slope = 6 Linear Ft.

1.5%

4.5%


Removal Limits

• If a secondary landing is necessary, check to see if a transition panel will also be needed to make the landing compliant.

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LandingLanding

Transition

Panel (S)


Removal Limits

• Verify removal limits will provide positive drainage as well as maintain existing drainage patterns.

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Removal Limits

• Once the Engineer and Contractor reach agreement on how to proceed the contractor may finish removals.

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Curb and Gutter

• Do not overlay PAR curb and gutter.

• New gutter face/flow line must match new road surface (See Standard Plans Sheet 3, note 7)

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Curb and Gutter

• 13% is the maximum rollover allowed.

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Curb and Gutter• Standard Plans Sheet 3, Note 3: For curb machine

placements start gutter slope transitions 10’ outside of all

curb ramps.

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Curb and Gutter

• When constructing directional ramps, the “triangular” concrete piece per MnDOT Standard Plans should be pouredintegral with the curb and gutter (directional curb).

• Maintain positive flow

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2-3%

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Curb and Gutter

• Flow Line Profile Alterations, Mill & Overlay Projects

• “Tabling” - maintaining a cross slope of 2% or less within a crosswalk. Required when a roadway is in a stop/yield condition and flow line exceeds 2% slope (and project scope allows)


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Curb and Gutter

• Flow Line Profile Alterations, Mill & Overlay Projects

• “Raising” - elevating the curb line enough to allow compliant ramps in vertically constrained areas.

Elevation Match point


Curb and Gutter

• Bituminous patching on ADA stand-alone projects 1.0% min. – 5.0% max.

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Curb and Gutter

• The contractor shall construct a contraction joint through the curb and gutter section at the bottom of the curb height transition at zero height curb (MnDOT 2531).

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Curb and Gutter: Adjustments• Special Situations: “Maximum Extent Feasible”

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5% Gutter

Output.


Curb and Gutter: Adjustments• Special situations: “Maximum Extent Feasible”

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5% Gutter outflow Landing


Detectable Warnings (Truncated Domes)

• Purpose of domes is to inform the user that they are at the edge of the roadway.

• Directionality only works in certain circumstances.

• Directionality should be done only when it works.

• Directional ramps are more difficult to construct with APS criteria.

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Detectable Warnings

(Truncated Domes)

• Standard Plate 7038A

• Includes both rectangular and radial

• Radial detectable warnings must accommodate existing radius dimensions to nearest 5’ increment

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Detectable Warnings

• Detectable Warning Surface shall contrast visually with adjacent gutter, roadway, or walkway, either a light-on-dark or dark-on-light.

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Detectable Warnings• (2531) The truncated domes shall be placed in concrete and

shall be pressed firmly into the concrete to the point that

concrete fills the vent holes on the truncated dome plates.

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Result of domes not installed correctly.


Detectable Warnings

• Good detectable edge with not so good placement. (Always check for structures in the PAR)

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Detectable Warnings

• Curb tapers are considered detectable edge when the taper starts within 3” of the edge of the truncated domes.

• Maintain a 2’ continuous detectable edge.

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3” No step through gaps

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Detectable Warnings• Recommendations from NCHRP

(National Cooperative Highway

Research Program)

• Where slip ramps “T” into trail:

Place domes at top of ramp

• Where trail starts/ends at roadway:

Place domes in the direction of travel

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Construction Finishing

• Spec 1503 Conformity with Contract Documents

• If the Contract requires a maximum or minimum dimension or value, the Contractor shall control the production and processing of the material and the performance of work so that the material or workmanship is not of borderline quality or dimension.

• Spec 2521.3D The Engineer will use a 10” straight edge to measure the surface.

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Construction Finishing• Spec 2521.3D The department considers deviations in the

surface greater than 3/16 inch and deviations in formed concrete greater than ½ inch from the required location as unacceptable work.

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Construction Finishing• Spec 2521.3D The department considers deviations in the

surface greater than 3/16 inch and deviations in formed concrete greater than ½ inch from the required location as unacceptable work.

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Construction Finishing• Spec 2521.3D Remove and replace unacceptable work as

directed by the Engineer.

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Construction Finishing• Joint Construction: Spec. 2521.3D2 The Contractor may

form or saw the joints in walking surfaces as approved by the

Engineer.

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Construction Finishing

• Joint Construction: Spec 2521.3D If forming the joints, round joints within the walking surface with a with a ¼ inch radius edge grooving tool.

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Driveway & Sidewalk ConstructionStandard Plans – Sheet 1

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5’ PAR

Driveway & Sidewalk Construction

Driveways• Commercial Apron Slope:

10% Max (8% Max Preferred)

• Residential Apron Slope:

12% Max (8% Max Preferred)

• PAR Width: 4’ Min (5’ Preferred)

• Try all options to maintain 5’

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1.5%

8%

Driveways• Maximize apron slopes

when driveway match-in

elevations are higher

than roadway elevations


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Driveways• Back of curb heights

• DW Curb Standard: 1”

• DW Curb Type 2

(Vertically Constrained): 2”

• DW Curb Type 3

(Vertically Constrained): 3”

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Doorway Landings

• Note 3) 6’ Min. PAR required

when adjacent to buildings.

• Note 4) 2/3 PAR to 1/3 Boulevard

should be used when feasible.

• Note 7) To minimize vibration

and rolling resistance, area

should be free of pavers,

stamped concrete, and/or

excessive jointing.


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Doorway

Landings2% ramp was constructed with landing lower than top of curb.

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2.0%

Construction: Lessons Learned

• Curb ramp is compliant, but it fits poorly into its surroundings,

and will be difficult to maintain.

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2%

Landing2%

2%


• Slopes shown are preferred and side slopes could have been grade flush, thus eliminating V-curb.

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2%-5%

Landing7%

2%-5%


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Alternate Pedestrian Access Routes

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APAR Layouts in the MN MUTCD

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2014 Temporary Traffic Control Zone Layouts Field Manual

Alternate Pedestrian Access Routes

Overview - Minnesota LTAP€¦ · 1 Section 5 Construction Considerations Fall, 2017 Ann Johnson,...

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