This project investigated the effect of different maximum trip speeds for six New Zealand routes. The study recorded actual mean speeds, time taken and fuel used. Speeds of 40km/h and 50km/h were tested on three short routes and speeds of 80km/h, 90km/h and 100km/h were tested on three long routes.
On the short routes, decreasing maximum speed decreased mean speed by 7% to 14% and increased travel time by 8% to 15%. Trips at 40km/h used 3% to 5% less fuel on the two Wellington routes but the difference in fuel used was not significant on the Auckland route. On the long routes, reducing trip maximum speed to 90km/h and 80 km/h reduced mean speed and increased travel time across all routes. Reducing maximum speed from 100km/h to 80km/h reduced mean speed by 8% to 12%, increased travel time by 9% to 13% and decreased fuel consumption by 14% to 15%.
Both fuel consumption and travel time were strongly correlated with trip maximum speed on the longer routes. Maximum speed was a significant predictor of fuel consumption and travel time on the short routes but traffic and idle time also had significant effects. This project has provided evidence of the effect on fuel consumption and travel time of decreasing maximum speed.
Keywords: idle time, mean speed, real world, speed, travel time