I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Project Purpose and Need October 2005
roadway. Along the eastbound frontage road, numerous structures such as utility poles,
mailboxes, and other obstructions encroach within the recommended clear zone. To meet
AASHTO guidelines, obstructions within the clear zone should either be removed or an
energy absorbing barrier placed between the obstruction and the roadway.
Railroad Conflicts
At-grade railroad crossings are a concern. At-grade railroad crossings have a higher
potential for serious vehicle/train accidents than do grade-separated railroad crossings.
Currently El Camino de Mañana and Cortaro Road both cross the railroad at-grade.
Although waiting for a train to pass an at-grade crossing is an inconvenience to most
motorists, it can pose time delays to emergency response personnel. Northwest Medical
Center, at an early public agency scoping meeting for this project, stated that the at-grade
crossings may result in extended delays for emergency medical personnel trying to reach
patients on the west side of I-10 and transporting them to hospital facilities on the east
side of I-10. These delays may be critical to some patients.
Connectivity
Transportation System Connectivity
Lack of access to destinations east of I-10 limits circulation within the area. The TIs at
Avra Valley Road and Cortaro Farms Road are approximately four miles apart. The
Town of Marana, as part of the Plan Update and ADOT, as part of the DCR Ruthrauff
Road to the Pima/Pinal County Line, both determined the need for a new major arterial
roadway that would cross the I-10 Corridor in the vicinity of Twin Peaks Road. In the
PAG Regional Transportation Plan, the Twin Peaks Road TI and roadway was projected
to serve a substantial amount of traffic both crossing and accessing I-10.
Bicycle and Pedestrian Connectivity
Within the study area, there are few pedestrian and bicycle amenities. According to the
Plan Update, on-street bicycle lanes and paved shoulders throughout the Town of
Marana are generally isolated facilities that do not interconnect with the surrounding
network. Within the area, pedestrian and bicycle amenities are provided only on Twin
Peaks Road from Silverbell Road to its eastern terminus. According to the Plan Update,
all new collector and arterial roadways should include sidewalks 6 feet in width on both
sides of the roadway to accommodate pedestrians, especially people with disabilities. The
Plan Update suggests also that new arterial roadways at a minimum include shared use
paths on one side of the roadway within the right-of-way.
The Town of Marana’s General Plan Update promoted alternative modes of
transportation and park and ride lots and stated that the connection of a paved system of
bicycle and pedestrian trails to the region’s Santa Cruz River Corridor system was of
importance. To improve connectivity to the Santa Cruz River Shared Use Path and other
facilities on both sides of I-10, improvements to bicycle and pedestrian facilities within
the area of the Twin Peaks Road TI are needed.
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
2-7
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D