Maximum length of a curb ramp?

[raydefan]

I have a situation where I need to design a curb ramp and if I used a 8.3% maximum grade, the curb ramp would never daylight because the adjacent road is at 10%. In situations like this, what is maximum length I should make the ramp? I thought I saw an ADA guideline once which stated to use 10' as the max, but I can find it anymore. Any thoughts?

Thanks,

Raydefan

 

[CarlB]

Since by ADA a ramp is between 5% & 8.33%, and a "curb ramp" can climb no more than 6", the longet ramp would be *just over* 5%, so would climb 0.50' at *just under* 10 feet. (Since this is a retrofit some other slighly relaxed standard migh apply)

But why make a handicap accessible ramp to a walkway that is not handicap accessible (since over 8.33%)? The roaute may be made more accessible to walkers/bikers if a ramp is provided (versus no ramp),but sounds like the ramp will need to be over 10% to match existing sidewalk.

 

[ACtrafficengr]

Not only wheelchair users use ramps. Ever try to drop a kid in a stroller off a curb without pitching him head-first into the street?

The ADAAG states ramps are required wherever a sidewalk crosses a curb, with no reference to whether or not it is an accessible route. The Access Board's position is even if it can't be made accessible, less inaccessible is still preferred.

An additional note: the guidelines recommend a 5' x 5' level (<2%) landing at intersections on steep roadways. They also have a criterion to prevent wheelchair footrests from scraping at the grade break where the ramp meets the roadway.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[civilman72]

There is a local agency in Colorado that helps out with questions such as this, see attached link. From my experience they are VERY helpful, but I believe they only support a few (Mountain) states. If you are not in their region, they may be able to tell you other agencies similiar to theirs in your area.

To answer your original question (max length of ramp?)- if you hold a 12:1 slope, you need handrails, and should have a flat ramp (2%) every 30'. So, I believe the answer to your original question is 30'.

Placing handrails adjacent to the ramp is required, but obviously having handrails adjacent a road is not desirable, especially in snow county. And installing a flat ramp (landing area) every 30' when adjacent to an existing steep roads makes for some very difficult/conspicuous/dangerous curb lines and grading.

I've run into this issue early in my career and numerous times since then. After calling the DBTAC, they explained to me that if you are installing a new sidewalk adjacent to an existing road, it is acceptable to match the existing grade of the existing road (and no landing areas or handrails are necessary). What they also clarified is that ADAAG ramp/grade requirements really come into play when you are designing a new sidewalk, on a new (or redeveloped) site. Whereas when the new walk is proposed in an existing road right-of-way, with existing infrastructure (roads, landscaping, utilities, etc.) it is encouraged that you attempt to meet the ADAAG requirements, but it is not "required."