Candidate for fully permeable shoulder retrofit validation site
Brief Summary of Phase II Bike Study (SPE 4.57).
The project was a continuation of a Phase I study that focused on bicycle club members
and their bicycles and state highways, and also on recent changes in Caltrans’ chip
seal specifications that resulted in larger stones in typically used seals.
Phase I report has been published.
This Phase II project included other types of riders, bicycles and more local
roads. The objective of this continued project (Phase II Bike Study for Local
Streets) was to conduct the bike study on local streets and use Phase I and II
results to prepare guidelines for design of preservation treatments suitable
for bicycle routes on state highways and local streets in California.
In Phase II, macrotexture and roughness as well as distresses were measured
for different preservation treatments on 67 road sections distributed across
five cities (Davis, Richmond, Sacramento, Reno and Chico) in northern California
and a number of Caltrans’ highway sections. Bicycle ride quality surveys were
conducted and collected data from a total of 155 participants. Correlations of
pavement texture, bicycle vibration and bicycle ride quality were
developed. Correlations between pavement roughness and distresses, correlations
of bike ride quality to roughness, and correlations between pavement texture and
treatment specifications were preliminarily explored. Models for bicycle ride
quality and physical rolling resistance were also developed. Long term monitoring
of pavement macrotexture for larger stone seals on LA-2, SLO-1 and Mon-198 has
also been completed to determine how much texture is reduced by traffic.
Major conclusions drawn from the results and analyses include:
Changes in Caltrans’ chip seal gradation specifications have resulted in higher
macrotexture values, as seen on LA-2, SLO-1 and Mon-198, as examples.
From preliminary (Phase I on highways + Phase II on streets) results, 80% of riders rate pavements
with Mean Profile Depth values 1.8 mm or less as acceptable; 50% rate MPD of 2.3 mm or less as acceptable.
Most slurries on city streets produce high acceptability across all cities.
A clear relationship was established between the critical aggregates sizes (#4 and #8) and MPD.
Pavement texture generally tends to decrease over time due to traffic, although
not yet below the “acceptable” levels (according to survey) on the sections being surveyed.
Both IRI and MPD are important parameters to determine whether riders find a particular section acceptable.
There is considerable variability among people and among sections that influences acceptability.
The presence of distresses, particularly cracking, reduces the ratings given to pavement by bicycle riders.
Important Note for Caltrans Users: Prior
to scheduling pavement preservation (preventive maintenance or CAPM) or roadway
rehabilitation work on flexible pavement highway sections, the District Materials
Engineer and/or the Project Manager should review
this spreadsheet to
ensure that the proposed project does not include sections active in
the “Quieter Pavement Research” (QPR) testing program. If the proposed
project is within a QPR test section, please
contact Linus Motumah of the
Caltrans Office of Pavement Design before scheduling the work.
To view maps that show where the sections are located, click the following
(or copy-and-paste it into a new browser window for a slightly larger view).
For more information,
contact John Harvey of the UCPRC or