sr 77/oracle road multimodal corridor profile study final report - Pima ...

distance of 3.8 miles. There is no roadside lighting north of River Road to the northern terminus
of the project, a distance of 31.3 miles. Intersection lighting exists at all signalized intersections.
The analysis computed the nighttime and daytime crash rates for each roadway segment and used
these values to compute the ratio of the nighttime to daytime crash rate. In addition, a procedure
used by the City of Tucson (Comprehensive Roadway Illumination Study – Phase IV, January
2003) to evaluate roadway lighting needs was employed to rank roadway segments. This
analysis takes into account geometric, operational, and roadside environmental factors to
compute an overall ranking score for each segment. The higher the ranking score, the more the
potential benefit from roadway lighting. A summary of the results from the lighting analysis is
provided in Appendix E. These results indicate that, in general, the unlighted segments of SR 77
have higher nighttime crash rates than the lighted segments. Six of the unlighted segments have
nighttime crash rates that are 2.2 to 3.5 times higher than the daytime crash rates. The segment
from Rancho Vistoso Boulevard to Tangerine Road has the highest night/day crash rate ratio of
3.5. The segments ranked the highest, considering all factors, are in the area from Saddlebrooke
Boulevard south to First Avenue. The five highest ranked segments considering all factors, in
order of ranking, are:
1. Tangerine Road to Hanley Boulevard
2. Pinto Lane to Golder Ranch Road
3. Golder Ranch Road to Wilds Road (low number of crashes on this segment does not
support a need for lighting)
4. Wilds Road to Rancho Vistoso Boulevard
5. First Avenue to Pusch View Lane
This analysis does not indicate that roadway lighting alone will improve the incidence of
nighttime crashes on these segments. It does suggest that lighting should be considered if the
already planned capacity improvements do not reduce the incidence of nighttime crashes.
5.1.11 SR 77 Access Points and Crashes
An analysis was conducted evaluating the relationship between the number of driveways and
total number of crashes along SR 77 road segments. This analysis was conducted by direction of
travel. Exhibits containing the physical characteristics (segment length, number of driveways
and unsignalized cross streets) and access related crash data (sideswipe, rear end, head on,
U-turn, left turn, and angle crashes) along SR 77 between the end segment and I-10 are provided
in Appendix D. State Route 77 was broken down into 29 segments from end segment to I-10 for
the initial analysis. Access points per mile were determined by number of driveways and
unsignalized cross streets within the road segment. Access related crashes is the sum of
sideswipe, rear end, head-on, U-turn, left turn and angle crashes that occur within the road
segment. Total crashes are from the five-year history in each direction of travel.
Comparing the number of access points per mile to access related crashes and total crashes for
northbound and southbound travel, revealed several trends.
• Access related crashes account for more than 50 percent of total crashes along the road
segments. This trend holds for 90 percent of the road segments in both directions.
SR 77/Oracle Road Multimodal Corridor Profile Study May 2007
Final Report Page 5-22