Airport Parkway Extended Traffic Impact Study (APETIS)
This page summarizes the portions of the APETIS report most relevant to the Alta Vista Corridor EA.
The bottom line: the APETIS report demonstrates that traffic modelling techniques which ignore induced traffic effects significantly underestimate increases in traffic that are the result of road expansion projects. In the Airport Parkway case the morning rush hour forecast increase in sections of Bronson were too low by as much as 51%. There has been no explanation other than induced traffic for this huge error. The APETIS report also demonstrates that you need to model both AM and PM rush hours.
Details:
Maxgroup Associates published a report on the Airport Parkway Extended Traffic Impact Study (APETIS) for the City of Ottawa in September 1999. That report documents the traffic forecasts done to predict the impact of adding ramps to the Airport Parkway at Hunt Club to allow commuters to use the Parkway to get downtown and back. It also documents the actual traffic observed after the ramps were added, which is what makes that report relatively unique and valuable. Most road building projects consist of planning the road, making forecasts and then building the road and that's all. Double checking if the forecasts were right doesn't fall into the mandate of most road building projects.
The APETIS report includes traffic forecasts for the Airport Parkway/Bronson corridor. Forecasts were done in both the morning and afternoon rush hours. Even though the afternoon rush hour is the normally the busiest for the city's road network as a whole, the morning rush hour was also studied in this case. Traffic's behaviour is significantly different in the AM from the PM in this case because the bottlenecks in the corridor are most pronounced at the north end.
Summary of actual traffic (number of cars) versus forecast taken from AM rush hour data from the APETIS report:
Road Segment From To Actual total in 1998
Forecast total for 1999 Forecast increase Actual total in 1999 Actual increase Error in forecast increase Percent error in forecast increase Airport Parkway Hunt Club Walkley 980 1800 820 1600 620 -200 -32% Airport Parkway Walkley Brookfield 910 1500 590 1550 640 50 8% Bronson Heron Sunnyside 2300 2520 220 2710 410 190 46% Bronson Canal Carling 1700 1920 220 2150 450 230 51% Bronson Carling Queensway 1600 1820 220 1860 260 40 15% By the way, overall traffic on other north-south arterials such as Bank and Main did not go down as the traffic increased on the Airport Parkway/Bronson corridor. The southern end of Bank saw a small reduction but northern end of Bank along with Main saw increases as a result of cut-through traffic from Bronson in the morning rush hour.
Implications for the Alta Vista Corridor EA:
- The Alta Vista Corridor just like the Airport Parkway/Bronson corridor has significant bottlenecks at the northern end. Failure to model morning rush hour will hide significant traffic issues. The consultant is currently proposing a 4-lane road in the Alta Vista Corridor without planning to look at traffic in the morning rush hour until after the the preferred solution is chosen. As a result, the consultant's road evaluation is incomplete.
- The consultant proposing a roadway for the Alta Vista Corridor is not taking into account the possibility of induced traffic and ignoring previously observed errors. This means the consultant's traffic forecasts underestimate traffic overall in road expansion scenarios. Their claims of traffic levels in the Alta Vista Corridor and on related arterials need to be adjusted upwards along with air quality impacts (pollution and green house gases).