From c5369caa458fb048db4f362d47259db68a6b5b11 Mon Sep 17 00:00:00 2001
From: Nicolas Chappe <74881848+nchappe@users.noreply.github.com>
Date: Sat, 13 Nov 2021 20:49:35 +0100
Subject: [PATCH] Fix: [Linkgraph] possible rounding errors for travel times of
 low-capacity links

---
 src/linkgraph/linkgraph.cpp | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/linkgraph/linkgraph.cpp b/src/linkgraph/linkgraph.cpp
index 2efbe19d15..7478118650 100644
--- a/src/linkgraph/linkgraph.cpp
+++ b/src/linkgraph/linkgraph.cpp
@@ -72,12 +72,15 @@ void LinkGraph::Compress()
 		for (NodeID node2 = 0; node2 < this->Size(); ++node2) {
 			BaseEdge &edge = this->edges[node1][node2];
 			if (edge.capacity > 0) {
-				edge.capacity = std::max(1U, edge.capacity / 2);
+				uint new_capacity = std::max(1U, edge.capacity / 2);
+				if (edge.capacity < (1 << 16)) {
+					edge.travel_time_sum = edge.travel_time_sum * new_capacity / edge.capacity;
+				} else if (edge.travel_time_sum != 0) {
+					edge.travel_time_sum = std::max(1ULL, edge.travel_time_sum / 2);
+				}
+				edge.capacity = new_capacity;
 				edge.usage /= 2;
 			}
-			if (edge.travel_time_sum > 0) {
-				edge.travel_time_sum = std::max(1ULL, edge.travel_time_sum / 2);
-			}
 		}
 	}
 }