History and background
During the 1980’s and 90’s, Maryland installed some APS of the cuckoo/chirp type at locations throughout the state, including Montgomery County, Frostburg, Lutherville, and Towson.
Maryland DOT, in response to concerns about mobility for persons who are visually impaired through unique intersections, such as roundabouts, and the addition of the APS section to the MUTCD, convened a committee in November 2000 to develop criteria for installation and prioritization plans
for installation of APS.
The committee consisted of representatives of the visually impaired community, traffic engineers, orientation and mobility specialists, local ADA coordinators and DOT staff.
The goals of the committee included:
The committee developed a prioritization checklist (see Appendix D).
This checklist has been used on approximately 40 intersections to date,
with scores ranging from 14 to 46 out of a possible total of 60. While each crossing receives a rating, the highest rating for any crossing is used for the intersection.
At this time, Maryland is considering any intersection with a rating greater than 36 to be a high priority. Eleven intersections are rated at this level and have either had APS installed or are under design for installation.
Maryland considers an APS to be a traffic control device and as such funding is from traffic control, highway construction and Federal funds.
APS type and features
Pushbutton-integrated APS manufactured by Polara Engineering
Description of intersection 1
Installation Example 1, Loch Raven and Taylor, is a large intersection with right turn islands, heavy traffic volumes and left turn lanes on all approaches.
APS Installation 1
Existing poles were used at this location with channelizing islands and uncontrolled right turn lanes in three of the four quadrants.
WALK indication is a speech message. The volume levels of the APS were carefully adjusted to prevent the WALK indication from being audible to pedestrians before they crossed the right turn lane. The speaker is blocked on the side away from the intersection. However, wind, humidity and large trucks can affect the sound levels and the signals may be audible from the sidewalk under certain conditions. In this case, the person who requested the signals is familiar with the geometry.
Description of intersection 2
Installation Example 2, Loch Raven and Glen Keith, is an intersection with low side street volumes. The APS is to cross the major street (Loch Raven) only. There are no pedestrian indications to cross the minor (Glen Keith) so APS were not installed for those crossings. The major street is quite wide, with a median island and a stop sign controlled service road along the west side of Loch Raven. Again, the volumes needed to be carefully adjusted. Vehicular signal pole was used for one APS but others were located close to the crosswalk on pedestrian signal poles.
APS Installation 2
Mr. Paulis of the Office of Traffic and Safety states that the location of pushbuttons and other APS equipment is of high importance in providing a properly operating system for pedestrians who are visually impaired. In many cases, it is not desirable to only use existing poles for the installation of APS. The installation of additional pedestal poles is often necessary to insure the proper location of APS relative to crosswalks and curb cuts.
Adjustment of initial volume levels for use has been an issue. Obtaining
the proper balance between the needs of the persons who are visually impaired and surrounding development while not presenting misleading information to pedestrians has proved to be difficult. Complicating the process are uncontrollable factors, that is, traffic noise and weather conditions such as wind and rain.
There have been some failures of the control boards, but these may not be excessive when considering that the equipment is a new and relatively recent design and the growing pains associated with new technology.
No formal evaluation has been conducted of installations. Most individuals who have requested the installations seem to be pleased.
Edward T. Paulis, Jr., Office of Traffic and Safety
Maryland State Highway Administration
7491 Connelley Drive
Hanover, MD 21076
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This site was developed under the sponsorship of the National Cooperative Highway Research Program.