Table of Contents

Appendix E 3.2 Analysis Results for Design 1

With the default actuated signal settings, an average cycle time of 102 seconds is estimated with displayed green times of 50 seconds for Phase A (maximum), and 40 seconds for Phase B. Highly oversaturated conditions, and therefore very long delays (level of service F), are estimated for the filter right turn movement from North as seen in Figure E 4 and Figure E 5. All other movements appear to operate satisfactorily, with the exception of the right turn movement from South (level of service E).

From Figure E 5, the right turn lanes on North and South approaches are seen to be operating as de facto exclusive lanes (right turns only) due to much longer delays experienced in these lanes (i.e. no through traffic uses these lanes which are specified as shared through and right turn traffic lanes). This indicates inefficient use of the road space available.

Optimisation of cycle time (as coordinated actuated signals) for minimising the average intersection delay value indicates that the performance of right turn movements can be improved significantly at an optimum cycle time of 75 seconds (displayed green times of 39 seconds for Phase A, and 24 seconds for Phase B). However, the right turn movement from the North approach is still highly oversaturated (average delay = 401.2 seconds). Furthermore, the coordination requirements may not allow the use of a shorter cycle time.

These results confirm the need for improvements to the intersection layout and signal phasing to cater for the right turn movement from the North approach in particular.

Figure E 4: Average delay and level of service estimates for Design 1 (based on default actuated signal settings)

Source: Akcelik and Associates (2009), ‘Intersection output provided by source’.

Figure E 5: Lane flow, capacity and performance results for Design 1 (based on default actuated signal settings)

Source: Akcelik and Associates (2009), ‘Intersection output provided by source’.