diff --git a/src/dsf/mobility/Road.cpp b/src/dsf/mobility/Road.cpp
index 5a850157..d69cf66b 100644
--- a/src/dsf/mobility/Road.cpp
+++ b/src/dsf/mobility/Road.cpp
@@ -83,6 +83,11 @@ namespace dsf::mobility {
     }
     m_transportCapacity = transportCapacity;
   }
+
+  double Road::density(bool normalized) const noexcept {
+    return normalized ? this->nAgents() / static_cast<double>(this->capacity())
+                      : this->nAgents() / (this->length() * this->nLanes());
+  }
   Direction Road::turnDirection(double const& previousStreetAngle) const {
     auto const deltaAngle{this->deltaAngle(previousStreetAngle)};
     if (std::abs(deltaAngle) >= std::numbers::pi) {
diff --git a/src/dsf/mobility/Road.hpp b/src/dsf/mobility/Road.hpp
index 5e9a3c3a..509ba183 100644
--- a/src/dsf/mobility/Road.hpp
+++ b/src/dsf/mobility/Road.hpp
@@ -28,7 +28,7 @@ namespace dsf::mobility {
     double m_length;
     double m_maxSpeed;
     int m_nLanes;
-    int m_capacity;
+    std::size_t m_capacity;
     double m_transportCapacity;
     std::string m_name;
     bool m_hasPriority = false;
@@ -103,6 +103,13 @@ namespace dsf::mobility {
     /// @brief Get the road's capacity, in number of agents
     /// @return int The road's capacity, in number of agents
     inline auto capacity() const noexcept { return m_capacity; }
+    /// @brief Get the road's density in \f$m^{-1}\f$ or in \f$a.u.\f$, if normalized
+    /// @param normalized If true, the road's density is normalized by the road's capacity
+    /// @return double, The road's density
+    double density(bool normalized = false) const noexcept;
+    /// @brief Check if the road is full
+    /// @return bool, True if the road is full, false otherwise
+    inline bool isFull() const final { return this->nAgents() == this->capacity(); }
     /// @brief Get the road's transport capacity, in number of agents
     /// @return double The road's transport capacity, in number of agents
     inline auto transportCapacity() const noexcept { return m_transportCapacity; }
@@ -134,10 +141,7 @@ namespace dsf::mobility {
     ///          - LEFT (delta is positive and not covered by the above conditions)
     Direction turnDirection(double const& previousStreetAngle) const;
 
-    virtual int nAgents() const = 0;
-    virtual int nMovingAgents() const = 0;
-    virtual double nExitingAgents(Direction direction, bool normalizeOnNLanes) const = 0;
-    virtual double density(bool normalized = false) const = 0;
+    virtual std::size_t nAgents() const = 0;
   };
 }  // namespace dsf::mobility
 
diff --git a/src/dsf/mobility/Street.cpp b/src/dsf/mobility/Street.cpp
index abe4cc72..1986d76a 100644
--- a/src/dsf/mobility/Street.cpp
+++ b/src/dsf/mobility/Street.cpp
@@ -161,23 +161,18 @@ namespace dsf::mobility {
     return pAgent;
   }
 
-  int Street::nAgents() const {
-    auto nAgents{static_cast<int>(m_movingAgents.size())};
+  std::size_t Street::nAgents() const {
+    auto nAgents{m_movingAgents.size()};
     for (const auto& queue : m_exitQueues) {
       nAgents += queue.size();
     }
     return nAgents;
   }
 
-  double Street::density(bool normalized) const {
-    return normalized ? nAgents() / static_cast<double>(m_capacity)
-                      : nAgents() / (m_length * m_nLanes);
-  }
-
-  int Street::nMovingAgents() const { return m_movingAgents.size(); }
+  std::size_t Street::nMovingAgents() const { return m_movingAgents.size(); }
   double Street::nExitingAgents(Direction direction, bool normalizeOnNLanes) const {
     double nAgents{0.};
-    int n{0};
+    std::size_t n{0};
     for (auto i{0}; i < m_nLanes; ++i) {
       if (direction == Direction::ANY) {
         nAgents += m_exitQueues[i].size();
diff --git a/src/dsf/mobility/Street.hpp b/src/dsf/mobility/Street.hpp
index 768cfaa1..64a87a20 100644
--- a/src/dsf/mobility/Street.hpp
+++ b/src/dsf/mobility/Street.hpp
@@ -130,15 +130,8 @@ namespace dsf::mobility {
       return m_exitQueues;
     }
     /// @brief  Get the number of agents on the street
-    /// @return Size, The number of agents on the street
-    int nAgents() const final;
-    /// @brief Get the street's density in \f$m^{-1}\f$ or in \f$a.u.\f$, if normalized
-    /// @param normalized If true, the street's density is normalized by the street's capacity
-    /// @return double, The street's density
-    double density(bool normalized = false) const final;
-    /// @brief Check if the street is full
-    /// @return bool, True if the street is full, false otherwise
-    inline bool isFull() const final { return this->nAgents() == this->m_capacity; }
+    /// @return std::size_t, The number of agents on the street
+    std::size_t nAgents() const final;
     /// @brief Get the street's stationary weight
     /// @return double The street's stationary weight
     inline auto stationaryWeight() const noexcept { return m_stationaryWeight; }
@@ -162,14 +155,14 @@ namespace dsf::mobility {
       return m_movingAgents;
     }
     /// @brief Get the number of of moving agents, i.e. agents not yet enqueued
-    /// @return int The number of moving agents
-    int nMovingAgents() const final;
+    /// @return std::size_t The number of moving agents
+    std::size_t nMovingAgents() const;
     /// @brief Get the number of agents on all queues for a given direction
     /// @param direction The direction of the agents (default is ANY)
     /// @param normalizeOnNLanes If true, the number of agents is normalized by the number of lanes
     /// @return double The number of agents on all queues for a given direction
     double nExitingAgents(Direction direction = Direction::ANY,
-                          bool normalizeOnNLanes = false) const final;
+                          bool normalizeOnNLanes = false) const;
     /// @brief Get the mean speed of the agents that have passed through the street
     /// @param bReset If true, the average speed data is reset after the computation
     /// @return Measurement<double> The (mean, std) speed of the agents that have passed through the street