weight-functions.js

"use strict";

const point = require('turf-point');
const distance = require('@turf/distance').default;


module.exports = {
    travelTimeWeightFn: travelTimeWeightFn,
};

function travelTimeWeightFn(a, b, props) {
    const highwaySpeeds = {
        motorway: 110,
        trunk: 90,
        primary: 80,
        secondary: 70,
        tertiary: 50,
        unclassified: 50,
        road: 50,
        residential: 30,
        service: 30,
        living_street: 20
    };

    const unknowns = {};

    let d = distance(point(a), point(b)) * 1000,
        factor = 0.9,
        type = props.highway,
        forwardSpeed,
        backwardSpeed;

    if (props.maxspeed) {
        forwardSpeed = backwardSpeed = Number(props.maxspeed);
    } else {
        let linkIndex = type.indexOf('_link');

        if (linkIndex >= 0) {
            type = type.substring(0, linkIndex);
            factor *= 0.7;
        }
    
        forwardSpeed = backwardSpeed = highwaySpeeds[type] * factor;
    
        if (!forwardSpeed) {
            unknowns[type] = true;
        }
    }
    
    if (props.oneway && props.oneway !== 'no' || props.junction && props.junction === 'roundabout') {
        backwardSpeed = null;
    }

    return {
        forward: forwardSpeed && (d / (forwardSpeed / 3.6)),
        backward: backwardSpeed && (d / (backwardSpeed / 3.6)),
    };
}