It will take ‘too long’ to get anywhere.
When there is no other traffic, all traffic lights are green and there were no hazards, give-ways or other reasons to slow down, travelling 2 miles at a maximum speed of 30mph will take 2 minutes. A maximum speed of 20mph will add 1 minute, but this is not the real world …
In light traffic, travelling 2 miles across March at a maximum speed of 30mph will take 5-6 minutes. A maximum speed of 20mph will add around 15-30 seconds.
At peak times, travelling 2 miles across March at a maximum speed of 30mph will take 10-15 minutes. A maximum speed of 20mph will add from nothing up to about 15 seconds.
Cars run badly at 20mph.
There is no evidence to suggest that cars run badly at lower speeds so long as the correct gear is selected. Most cars will run perfectly fine in 2nd or 3rd gear, but if the gear selected is too low, the revs will be high and if the gear is too high, the engine will be labouring. In both cases the car may be burning unnecessary fuel and putting unnecessary strain on the engine. The answer is to select the correct gear for the speed the vehicle is travelling.
If drivers are watching their speedo’s, they will have accidents.
Drivers need to keep an eye on their speedometer to ensure that they do not go above the posted speed limit regardless of what the speed limit is. This is a basic driving skill which needs to be done in all circumstances. Drivers can and should watch their speed in all circumstances.
Pedestrians will walk into the roads.
Pedestrians will walk into the roads, (usually to cross them), if they deem it safe to do so. If traffic is travelling at 20mph it will be safer for them to cross. However it would be foolish for any pedestrian to walk in front of a moving vehicle in the hope that the driver may stop. Pedestrians usually have an inbuilt sense of self preservation and will take care, but mistakes are made by everyone and lower speed limits reduce the consequences of any mistake.
It will cause traffic jams.
Traffic flows better at lower speeds.