Pedestrian interval times (2009 MUTCD gone too far?)

[tradephoric]

I found this response in the frequently asked questions on the FHWA website that sheds more light on the purpose of the 3.0 ft/sec calculation in paragraph 14.

Q: The 2009 MUTCD has lowered the recommended walking speed for calculating the Pedestrian Clearance Time from 4.0 ft/sec. to 3.5 ft/sec. But Section 4E.06 indicates that a walking speed of 3.0 ft/sec is also to be used. Where should 3.0 ft/sec be used instead of 3.5 ft/sec?

A: The 3.0 ft/sec walking speed is indicated for use in paragraph 14 of Section 4E.06. This is used as a "cross-check" calculation to determine if there is sufficient crossing time for slower pedestrians, such as those in wheelchairs or who are visually disabled, to cross wide streets. In this particular calculation, instead of using the curb-to-curb crossing distance, the distance used is measured from the pedestrian pushbutton (or, if none, from 6 feet back from the face of curb) to the far side curb. That distance in feet is divided by the 3.0 ft/sec assumed walking speed to obtain a value in number of seconds (for purposes of this example, let's call this value the "Slower Ped Time.") The Walk interval is allowed to be used to satisfy the calculated "Slower Ped Time," so the sum of the duration of the Walk interval (typically at least 7 sec.) plus the duration of the Pedestrian Clearance Time that was previously calculated using the regular 3.5 ft/sec walking speed is compared to the calculated "Slower Ped Time." For very wide streets, generally in the range of 95-100 feet or more, the calculations may find that the Slower Ped Time exceeds the calculated Pedestrian Clearance Time. In that case, the Walk interval, rather than the Pedestrian Clearance Time, should be increased in duration to satisfy the 3.0 ft/sec criterion.

Now consider the guidance in paragraph 10:

10   Where pedestrians who walk slower than 3.5 feet per second, or pedestrians who use wheelchairs, routinely use the crosswalk, a walking speed of less than 3.5 feet per second should be considered in determining the pedestrian clearance time.

If there is a concern that pedestrians won't be able to cross in time, the walking speeds should be adjusted based on the guidance found in paragraph 10.  Paragraph 14 allows for a "slower pedestrian"  walking at 3.0 ft/sec to complete the crossing in time ONLY if they start their crossing at the beginning of the walk interval.  The assumption that the "slower pedestrian"  will start their crossing at the beginning of the walk interval is a bad assumption to make since pedestrians have been taught they can cross at any point during the walk interval.  Adding several extra seconds of walk time based on the guidance in paragraph 14 does nothing to ensure that a "slower pedestrian"  will actually be crossing during those extra seconds of walk provided. 

Paragraph 10 & 14 seem redundant and would love to see paragraph 14 removed from the MUTCD in the next revision.