Deciding on a corridor to study for the Connected Corridors project involved:
- Identifying possibilities and narrowing the focus
- Gathering information about the potential areas
- Evaluating the choices according to the selection criteria
- Making a go/no-go decision
Narrowing the focus
We needed to identify which region of the state, which Caltrans district, and ultimately which corridor the project would focus on. To do so, we initially consulted with Caltrans Headquarters, our sponsoring partner on the project. Of the four major metropolitan areas in California – Sacramento, the San Francisco Bay Area, Los Angeles, and San Diego – it was decided to concentrate on the LA area. In addition to its well-known congested freeways, LA seemed like a suitable choice because it had other characteristics we were looking for:
- An urban area. We wanted to study an urban corridor, and LA has greater urban density and far more traffic than Sacramento.
- No other ICM projects underway. While there are ICM projects in other large metropolitan areas of the state, including the San Francisco Bay Area and San Diego, LA had no other ICM projects taking place.
Preliminary data gathering and assessment
We began gathering basic data on the LA region to identify potential transportation corridors that contain, at a minimum, a freeway and parallel arterial. The map shows what we considered:
We also began compiling statistics from the corridors in Caltrans districts 7, 8, and 12. We wanted a fuller and more quantified picture of their transportation characteristics, in order to consider several alternative corridors. Click the picture below to see a spreadsheet of the kinds of data we gathered:
After reviewing our preliminary data, we again consulted with Caltrans Headquarters, who also polled the Operations Division chiefs in the LA Caltrans districts to see if they had suggestions for a particular corridor. We also spoke with the largest transportation agency in the LA area, the Los Angeles County Metropolitan Transportation Authority (Metro). From these discussions, it was decided to focus on Caltrans District 7 and, within that district, on the I-710 freeway (at least initially). The I-710 seemed like a viable candidate because, in addition to having the basic attributes of a corridor, it was heavily traveled by large volumes of both public and commercial traffic, experienced serious congestion, and presented a challenging problem where much could be learned and potentially improved.
We began investigating I-710 in greater detail to assess its suitability for an ICM pilot. This three-month analysis involved examining:
- Traffic flow patterns and congestion hotspots on the freeway, using PeMS data
- Available capacity along the surrounding arterials, using data that could be extracted from traffic impact studies
- Existing transit services and park-and-ride lots
- The feasibility of implementing various traffic management strategies
Like any potential corridor, I-710 exhibited advantages and disadvantages for an ICM project, and the purpose of our detailed evaluation was to reveal them. This enabled us to consider any areas of concern and see how they could be mitigated.
Click the pictures below to see our evaluation results:
Concerns and Mitigation
Based on the detailed evaluation and the areas of concern, we ultimately decided, in consultation with our project partners, that the I-710 corridor was not the best choice for the project. Among the key issues were:
- The extent to which congestion problems along the freeway are caused by heavy trucking activities and roadway geometry factors
- Political issues associated with the option of pushing trucks onto nearby arterials
- The financial stability of cities along the I-710 corridor
- The distance to reach light-rail stations from the freeway
- The lack of park-and-ride lots within the corridor
While the corridor had many positive characteristics, those were outweighed by concerns which could not, finally, be realistically mitigated. We therefore turned to considering alternatives.