Purpose & Need
The purpose of the project is to improve traffic congestion, operations, and safety; provide facilities for transit and pedestrians; and encourage economic redevelopment along the SR-99 corridor through the city of Des Moines.
The existing roadway is an undivided five-lane facility with a two-way left-turn lane (TWLTL) and paved shoulders. Significant segments of the roadside have unlimited or undefined access.
Initial Design Concept
To increase capacity and mobility and relieve congestion, SR-99 will undergo changes in the following areas: roadway cross-section; the placement and type of intersection signals; pedestrian features; access control; and aesthetic treatments.
One of the specific features that will be included in this project is a landscaped median that eliminates the existing two-way left-turn lane. The median is installed to improve both pedestrian and vehicular safety. A low profile concrete barrier protects the treed median. An evaluation of the median design is being conducted to determine the impact of the treed median design on vehicular and pedestrian safety. In addition, curbs and gutters will be installed along the highway, and a six-foot landscaped planter will be built on each side of the street.
The project will also install equipment needed to support transit signal priority. Des Moines and King County Metro may consider the installation as a trial project. A High Occupancy Vehicle and Business Access lane will be added in each direction of the route, as well as bus pullouts and new transit shelters. Other features will be included to support the pedestrian activity, such as sidewalks on both sides of the highway, new street and sidewalk lighting, and a pedestrian-activated signal.
Two new signals will be installed, and two existing signals will be upgraded. Turn lanes will be added where appropriate, and driveways will be consolidated.
Gateway treatments will be constructed at either end of the project with "Welcome to Des Moines" signs and steel sailboats on poles (which will be able to spin like weathervanes).
Funding
Project funding sources include federal, state, and local funds.
The total project budget is about $15 million.
Challenges
- Community collaboration
- Funding for the project
- Construction under traffic
- Right of way acquisition
- Environment impacts
- Relocating utilities
Solutions
- Public participation
- City contributed more money
- Work with contractor to lessen
traffic impact
- Work on design elements without
affecting budget
- Communication with other
agencies
- Coordinate work with utilities
companies before construction
started
SR-99 Des Moines case study
