traverse *_link roads at a significantly lower speed than the main link, fixes #1174

Author: DennisOSRM

features/car/speed.feature

@@ -9,15 +9,15 @@ Feature: Car - speeds
         Then routability should be
             | highway        | oneway | bothw        |
             | motorway       | no     | 72 km/h      |
-            | motorway_link  | no     | 60 km/h      |
+            | motorway_link  | no     | 36 km/h      |
             | trunk          | no     | 67 km/h +- 1 |
-            | trunk_link     | no     | 55 km/h +- 1 |
+            | trunk_link     | no     | 32 km/h +- 1 |
             | primary        | no     | 52 km/h +- 1 |
-            | primary_link   | no     | 48 km/h      |
+            | primary_link   | no     | 24 km/h      |
             | secondary      | no     | 43 km/h +- 1 |
-            | secondary_link | no     | 40 km/h      |
+            | secondary_link | no     | 20 km/h      |
             | tertiary       | no     | 32 km/h      |
-            | tertiary_link  | no     | 24 km/h      |
+            | tertiary_link  | no     | 16 km/h      |
             | unclassified   | no     | 20 km/h      |
             | residential    | no     | 20 km/h      |
             | living_street  | no     |  8 km/h      |

profiles/car.lua

@@ -13,15 +13,15 @@ restriction_exception_tags = { "motorcar", "motor_vehicle", "vehicle" }
 
 speed_profile = {
   ["motorway"] = 90,
-  ["motorway_link"] = 75,
+  ["motorway_link"] = 45,
   ["trunk"] = 85,
-  ["trunk_link"] = 70,
+  ["trunk_link"] = 40,
   ["primary"] = 65,
-  ["primary_link"] = 60,
+  ["primary_link"] = 30,
   ["secondary"] = 55,
-  ["secondary_link"] = 50,
+  ["secondary_link"] = 25,
   ["tertiary"] = 40,
-  ["tertiary_link"] = 30,
+  ["tertiary_link"] = 20,
   ["unclassified"] = 25,
   ["residential"] = 25,
   ["living_street"] = 10,