HomeMy WebLinkAboutR_MEF_NW_Ramp_170711_v4
Bruce S. MacVeigh, P.E.
Civil Engineer/Small Site Geotechnical
14245 59th Ave. S. Tukwila, WA 98168 Cell Ph: 206-571-8794
February 24, 2020
Subject: Maximum Extent Feasible (MEF) Evaluation - ADA Ramp Reconstruction, Northwest Corner of Cedar Avenue S. and S. 4th Street,
Renton, WA
Project Description.
A new single family residence is being constructed on the southwest corner of
the intersection of Cedar Avenue S. and S. 4th Street. A requirement of the residential permit is to upgrade adjacent right-of-way where feasible. The sidewalk fronting the property along S. 4th Street will be replaced in kind
due to the poor condition of the walkway.
The existing ADA ramps on that corner and to the north across S. 4th Street are to be reconstructed to the maximum extent feasible to current WSDOT standards.
This evaluation discusses the design for the reconstruction of the ADA ramp on the northwest corner of the intersection.
Highway Parameters.
Design Matrix - Asphalt roadway with concrete curb, gutter and sidewalk Road Classification - Neighborhood arterial or collector Funding Source - Private
Posted/Design Speed - 25 mph
Average Daily Traffic - 500 trips per day (estimate) Truck Percent - 2 percent (estimate) Access Management Classification - None
Existing Pedestrian Facilities. The concrete walkway on Cedar Avenue S. has a total width of 6.5 feet, including curb width. There is no planting strip. The walkway on S. 4th Street
is 5 feet wide, with a 4.5 foot planting strip and 6” width curb.
REVISION
Received: 02/26/2020 / aalexander
BUILDING DIVISION
PR19000003
B19000388
V4
REVISION Received: 01/13/2021 / aalexander
BUILDING DIVISION
PR19000030
B19000388
V6
APPROVEDBUILDING DIVISION
THIS SET OF APPROVED PLANS MUST BE ON THE JOB AT ALLTIMES DURING CONSTRUCTION. THIS BUILDING IS NOT TO BEOCCUPIED UNTIL AFTER FINAL INSPECTION BY THE RENTONBUILDING DIVISION AND RECEIPT OF CERTIFICATE OFOCCUPANCY.APPROVAL SHALL NOT BE CONSTRUED AS THE AUTHORITY TOVIOLATE OR CANCEL ANY PROVISIONS OF CODES, ORDINANCES,OR OTHER REGULATIONS ENFORCED BY THIS CITY.DATE: 07/15/2021
The street slope of Cedar Avenue S. is downward to the north with a slope of about 9.9 percent.
The street slope of S. 4 th Street is downward to the west at about 16.1 percent. The related walks have the same slope. The existing ADA ramp is older and consists of a standard trapezoid ramp with
minimal landing due to limited width of walkway to right-of-way line. The landing is 6” above street flow line elevation. It has the impressed grid pattern on the ramp surface. It is slightly more oriented to the east rather perfectly at the corner due to an old power pole and utility boxes. It was constructed to an older standard. It is in poor condition.
Pedestrian Design Standards. Per Curb Ramps, WSDOT, DM Section 1510.09.
Running Ramp Slope = 1/12 max. Side Ramp Slope = 1/48 max. Walk Side Slope = 1.5 to 2 percent Side Slopes = 1/10 max.
Landing Dimensions = 36” x 36” min. Proposal.
To replace the entire ramp and landing area, and to extend walkway transitions to the north and west 15 feet to match existing walkway slopes. The reconstruction would lower the entire ramp and landing area to flow line depth, with ramp slopes reduced to the maximum possible to the 1.5 to 2 percent upslope.
The transition runs of walk will have slightly reduced down slopes due to the lowering of the ramp and landing area. Note that the runs of walkway, while reduced from their original slope, will still
be in excess of current design criteria of 1/12 (of 8.33 percent) A current standard 18” wide warning strip will be provided on the ramp prior to the curb line.
Justification. The combined ramp and landing will more or less meet available design standards in horizontal dimensions, and will have surface slopes meeting
design standards. The transition runs cannot meet the 1/12 maximum slope standard due to the slopes of the existing streets and their related walkways. Slopes in the transition runs will still be an improvement over the existing walkway slopes in
those sections. The only true solution is to regrade the streets of the entire hillside neighborhood. That is obviously not feasible.
Submitted: Submitted concurrently with this evaluation are construction plans showing the proposed ADA ramp and landing reconstruction.
Bruce S. MacVeigh, P.E.
Civil Engineer
joenguyenrentonadarampjustificationnwramp02/1830