Google Maps Api straight (shortest) route - google-maps

Question

I am currently trying to find a way how to get a straight route with Google Maps Api V3.
I already managed it to use geocode and the directions service to get a route from point A to point B, including two alternative routes. I also experimented with "No highways" and "No tolls" but nothing appears to solve this problem entirely...
At the moment I check the three given routes for lowest miles but this has to be proven not really to be the shortest route.
I am not searching the fastest or quickest route but just a straight route with as low miles as possible.
As I did not find any thread by using google explaining something like I need I ask you. Maybe somebody has a solution here...
P.S.: I also can't use the "Pedestrian Mode" as this is used as a navigation help for our local fire trucks when our mounted navigation systems do not work again.
This is also the reason why we need as low kilometers as possible - when driving a firetruck round here the fastest route is 99% the one with lowest miles but the Api won't let me decide that and insist on using principal roads

Answer 1

To obtain the shortest route from A to B I would suggest to make different queries with the “alternatives=true” parameter, playing with the “avoid” parameter between avoid=toll, avoid=highways, and then I would compare all results to pick the shortest route.
directionsService = new google.maps.DirectionsService;
//avoiding tolls
directionsService.route({
origin: {
'placeId': originId
},
destination: {
'placeId': destinationId
},
provideRouteAlternatives: true,
avoidTolls: true,
travelMode: google.maps.TravelMode.DRIVING
}, function(response, status) {
if (status === google.maps.DirectionsStatus.OK) {
routesResponses.push(response);
}
else {
window.alert('Directions request failed due to ' + status);
}
});
//avoiding highways
directionsService.route({
origin: {
'placeId': originId
},
destination: {
'placeId': destinationId
},
provideRouteAlternatives: true,
avoidHighways: true,
travelMode: google.maps.TravelMode.DRIVING
}, function(response, status) {
if (status === google.maps.DirectionsStatus.OK) {
routesResponses.push(response);
}
else {
window.alert('Directions request failed due to ' + status);
}
//Results analysis and drawing of routes
var fastest = Number.MAX_VALUE,
shortest = Number.MAX_VALUE;
routesResponses.forEach(function(res) {
res.routes.forEach(function(rou, index) {
console.log("distance of route " +index+": " , rou.legs[0].distance.value);
console.log("duration of route " +index+": " , rou.legs[0].duration.value);
if (rou.legs[0].distance.value < shortest) shortest = rou.legs[0].distance.value ;
if (rou.legs[0].duration.value < fastest) fastest = rou.legs[0].duration.value ;
})
})
console.log("shortest: ", shortest);
console.log("fastest: ", fastest);
//painting the routes in green blue and red
routesResponses.forEach(function(res) {
res.routes.forEach(function(rou, index) {
new google.maps.DirectionsRenderer({
map:map,
directions:res,
routeIndex:index,
polylineOptions:{
strokeColor: rou.legs[0].duration.value == fastest? "red":rou.legs[0].distance.value == shortest?"darkgreen":"blue",
strokeOpacity: rou.legs[0].duration.value == fastest? 0.8:rou.legs[0].distance.value == shortest? 0.9: 0.5,
strokeWeight: rou.legs[0].duration.value == fastest? 9:rou.legs[0].distance.value == shortest? 8: 3,
}
})
})
})
});
}
}

Answer 2

I use a solution, as I said here, that calls route service once and filters the results in a way that you find usefull. In my example, I'm calculating the shortest route.