Problem 1: Maxwell Road

Discussion
We’ve used this intersection to study a number of issues. It has been a logical place to start the case study, since it’s the intersection where the traffic volumes have changed the most. We’ve found that the intersection’s geometry will have to change substantially. We’ve needed a new northbound approach and we’ve found it useful to reconfigure the southbound approach. Our best solution uses three lanes southbound (left, through, and right) and three lanes northbound (left, through, and right). This lets us serve the northbound and southbound right turns concurrent with the eastbound and westbound lefts, which shortens the cycle length and reduces delays and queues.

We haven’t presented all of the analyses that would be required to do a complete traffic impact assessment. Rather, we’ve used certain conditions to illustrate important ideas related to the use of the HCM. We’ve used the PM Existing condition to look at arrival patterns, skipped phases, and differences in LOS stemming from the use of data from different sources. We’ve used the PM With condition to look at changes in LOS due to the addition of the site-related traffic, the relationship between geometric improvements and LOS, differences between planning and operational analyses, and the role of uncertainty in affecting the results obtained.

We don’t know for sure that the new configuration we’ve identified is the best. We’ve focused only on the PM With condition. It’s possible that the AM With or some other condition would work better with some other configuration. That’s something you’d have to do to complete the impact assessment.