Estimation of Traffic Impacts

There are three new developments on Loop 360 - San Clemente at Davenport, Capital Ridge Office and Hotel, and Point West at Marshall Ranch. The three big developments are going to add a lot of traffic to Loop 360.

I calculated the average daily trip generation from the Institute of Traffic Engineers' Trip Generation Manual. The traffic on Loop 360 was obtained from TxDOT's Annual Average Daily Traffic Counts for 2013 posted on the CAMPO web site. The comparison of new traffic generated by the developments with Loop 360 was to the closest point of measured traffic. The data on the sites were obtained from their web sites or on this blog.

Capital Ridge has 213K sq ft of office space and a 198 room hotel generating 4,328 trips daily about 9% increase in the Loop 360 traffic near the site.

San Clemente has 716K sq ft of office space and 30K sq ft of retail generating 7,514 trips daily about an increase of 14% in the Loop 360 traffic near the site.

Point West at Marshall Ranch will have 350K sq ft of office space generating 3,500 trips daily about 9% increase in the Loop 360 traffic near the site.

The percent impacts are only approximate because of the unknown actual traffic patterns that will develop. And while it is tempting to add all the new trips together, again it will depend upon the actual traffic patterns that will develop, and beyond the scope of this simple analysis.

The one that concerns us most is Point West. As stated above, it is estimated to generate about 3,500 trips per day on average. If that much traffic came through Lost Creek Blvd., the traffic on Lost Creek would go from 11,000 to 14,500, a 32% increase. Fortunately, we don't have to be concerned about that possibility, as Point West has a direct access to Loop 360, and the developers are working on getting access to Las Cimas Parkway.

With that in mind, the impact of traffic on the Lost Creek Blvd. and Loop 360 intersection becomes important. To estimate that, as we only have average daily traffic counts, the following assumptions are made:

• Half of the traffic going into Point West occurs in the AM
• Half of the traffic exiting Point West occurs in the PM
• Half of the traffic going to and coming from Point West is from the North
• Half of the traffic going to and coming from Point West is from the South

The following drawing results from those assumptions:

Red Indicates Egress at Las Cimas Blvd. Blue Indicates Egress Direct to Loop 360. Fractions are the Fraction of the Average Daily Traffic

This indicates that Point West will increase the average daily traffic through the Loop 360 – Lost Creek intersection by about 7% with direct ingress/egress to Loop 360. That would be reduced to about 5% if the traffic ingress/egress was Las Cimas Parkway, or Las Cimas Parkway and directly to Loop 360, assuming all people leaving the facility and wanting to go North would opt for the Las Cimas Parkway exit.

An actual traffic impact study will be made by the developers of Point West during the process of requesting a new zoning of the land. It's best to wait for the professional study. This estimate was made because there is concern about the traffic impact of Point West in the community. Consider this only a gross sizing of the traffic impacts.