Hill driving is not ideal for getting the maximum fuel efficiency from a vehicle. Most drivers know that. Endless gear changes, the extra fuel burned dragging a heavy load up the hill, then using engine braking or gear changes to slow your descent on the other side. But what can you do about it?
Not a lot if there’s only one way to your destination but now there’s advanced GPS routing that could show you a better way.
Hill Driving – The Enemy of Fuel Economy
Most articles offering advice on reducing fuel consumption, or hypermiling as it’s sometimes referred to, will tell you that hills are the antithesis of good fuel economy, with starting on a hill the absolute worst thing you can do when trying to achieve fuel efficiency. The combination of a cold engine (it is at its lowest efficiency at this point) and building up speed on a gradient draws the most gas and seriously impacts on your economy.
Some have actually attempted to calculate the extra fuel required to climb a gradient and while it might have been brushed off as extremist in the happy days of reasonable gas prices, today it might get a second look.
A forum discussing the negative impact of hilly terrain on fuel consumption claimed that to gain the “potential energy” a vehicle will have at the top of an incline an engine will burn an additional 0.085 gallons per 1000 feet climbed. Forum members discussed other formulas and rules of physics to describe the drain on fuel use when ascending or descending hills so I’ll warn you now it does get technical (as you would expect of Prius owners when talking about their favorite subject!) but the main point to take away is that no matter how good a driver you are, hills will work against your efforts to save fuel.
So how can you get round this mountain of a problem?
GeoBase taps into Road Incline Data
Telogis GeoBase, the mapping engine used by navigation engineers around the world, offers developers the option of tapping into ADAS (Advanced Driver Assistance Systems) information to route vehicles by road incline.
A tutorial on the GeoBase developer’s portal explains the step-by-step process involved with querying the ADAS database for road incline information then feeding that back into the routing calculation.
In the image below, the red sections of the route indicate an incline (in the direction of travel), the green sections indicate a decline, and the yellow sections indicate that the road is level (that is, within ±0.5°).
ADAS provides measurements at a range of points along a given street (identified by the LinkID) with the slope measured in degrees and returned as an array, with each point assigned a value (slope), which is either a positive number (the road is going up or inclining) or negative (the road is going down or declining). A value within 0.5 degrees of zero is interpreted as essentially flat.
A route designed to be fuel efficient, or green, might suggest an alternative street while slightly longer is flatter and will burn less fuel.
GPS and Road Gradient – Useful Data
Road gradient information has a wide range of uses, and not just for navigating around hilly terrain to save fuel. Trucks carrying extremely heavy loads or vehicles that lack the required pulling power may have to avoid attempting to climb hills.
Steep gradients may be a safety hazard, particularly in situations where they are not obvious to the driver. GPS units could provide an early warning system to help drivers safely negotiate a sudden up or downhill section of road.
ADAS – More to come
ADAS is delivering a wealth of information that could assist drivers to not just be more economical and reduce GHG emissions, but make the roads safer for everyone. Geospatial mapping engines such as Telogis GeoBase are helping programmers to take advantage of this data to improve the driving experience, and that’s great news for fleets and commercial drivers using Telogis telematics!