diff --git a/R/slopes.R b/R/slopes.R
index 0c95f1a..d781eb5 100644
--- a/R/slopes.R
+++ b/R/slopes.R
@@ -215,6 +215,7 @@ slope_matrices = function(m_xyz_split, fun = slope_matrix_weighted, ...) {
 #'   datasets. Default: `"bilinear"`.
 #' @param fun The slope function to calculate per route,
 #'   `slope_matrix_weighted` by default.
+#' @inheritParams slope_vector
 #' @importFrom methods is
 #' @return A vector of slopes equal in length to the number simple features
 #'   (rows representing linestrings) in the input object.
@@ -224,13 +225,16 @@ slope_matrices = function(m_xyz_split, fun = slope_matrix_weighted, ...) {
 #' dem = dem_lisbon_raster
 #' (s = slope_raster(routes, dem))
 #' cor(routes$Avg_Slope, s)
+#' slope_raster(routes, dem, directed = TRUE)
+#' slope_raster(sf::st_reverse(routes), dem, directed = TRUE)
 slope_raster = function(
   routes,
   dem,
   lonlat = sf::st_is_longlat(routes),
   method = "bilinear",
   fun = slope_matrix_weighted,
-  terra = has_terra() && methods::is(dem, "SpatRaster")
+  terra = has_terra() && methods::is(dem, "SpatRaster"),
+  directed = FALSE
   ) {
   if(is.na(lonlat)) {
     stop(
@@ -245,7 +249,7 @@ slope_raster = function(
   # colnames(m)
   z = elevation_extract(m, dem, method = method, terra = terra)
   m_xyz_df = data.frame(x = m[, "X"], y = m[, "Y"], z = z, L1 = m[, "L1"])
-  res = slope_xyz(m_xyz_df, fun = fun, lonlat = lonlat)
+  res = slope_xyz(m_xyz_df, fun = fun, lonlat = lonlat, directed = directed)
   res
 }
 
@@ -260,14 +264,25 @@ slope_raster = function(
 #' @examples
 #' route_xyz = lisbon_road_segment_3d
 #' slope_xyz(route_xyz, lonlat = FALSE)
-slope_xyz = function(route_xyz, fun = slope_matrix_weighted, lonlat = TRUE) {
+#' slope_xyz(route_xyz, lonlat = FALSE, directed = TRUE)
+slope_xyz = function(
+  route_xyz,
+  fun = slope_matrix_weighted,
+  lonlat = TRUE,
+  directed = FALSE
+  ) {
   if(inherits(route_xyz, "sf") | inherits(route_xyz, "sfc")) {
     lonlat = sf::st_is_longlat(route_xyz)
     route_xyz = as.data.frame(sf::st_coordinates(route_xyz))
   }
   if("L1" %in% colnames(route_xyz)) {
     m_xyz_split = split(x = route_xyz, f = route_xyz[, "L1"])
-    res = slope_matrices(m_xyz_split, lonlat = lonlat, fun = fun)
+    res = slope_matrices(
+      m_xyz_split,
+      lonlat = lonlat,
+      fun = fun,
+      directed = directed
+      )
   } else {
     # todo: add content here if data frame was generated by sfheaders
     # or another package that does not call id colums 'L1' by default
diff --git a/man/slope_raster.Rd b/man/slope_raster.Rd
index ecf277f..da90a35 100644
--- a/man/slope_raster.Rd
+++ b/man/slope_raster.Rd
@@ -10,7 +10,8 @@ slope_raster(
   lonlat = sf::st_is_longlat(routes),
   method = "bilinear",
   fun = slope_matrix_weighted,
-  terra = has_terra() && methods::is(dem, "SpatRaster")
+  terra = has_terra() && methods::is(dem, "SpatRaster"),
+  directed = FALSE
 )
 }
 \arguments{
@@ -32,6 +33,10 @@ datasets. Default: \code{"bilinear"}.}
 \item{terra}{Should the \code{terra} package be used?
 \code{TRUE} by default if the package is installed \emph{and}
 if \code{dem} is of class \code{SpatRast}}
+
+\item{directed}{Should the value be directed? \code{FALSE} by default.
+If \code{TRUE} the result will be negative when it represents a downslope
+(when the end point is lower than the start point).}
 }
 \value{
 A vector of slopes equal in length to the number simple features
diff --git a/man/slope_xyz.Rd b/man/slope_xyz.Rd
index ce5f10b..31327a4 100644
--- a/man/slope_xyz.Rd
+++ b/man/slope_xyz.Rd
@@ -4,7 +4,12 @@
 \alias{slope_xyz}
 \title{Extract slopes from xyz data frame or sf objects}
 \usage{
-slope_xyz(route_xyz, fun = slope_matrix_weighted, lonlat = TRUE)
+slope_xyz(
+  route_xyz,
+  fun = slope_matrix_weighted,
+  lonlat = TRUE,
+  directed = FALSE
+)
 }
 \arguments{
 \item{route_xyz}{An sf object with x, y, z dimensions}
@@ -13,6 +18,10 @@ slope_xyz(route_xyz, fun = slope_matrix_weighted, lonlat = TRUE)
 \code{slope_matrix_weighted} by default.}
 
 \item{lonlat}{Are the coordinates in lon/lat order? TRUE by default}
+
+\item{directed}{Should the value be directed? \code{FALSE} by default.
+If \code{TRUE} the result will be negative when it represents a downslope
+(when the end point is lower than the start point).}
 }
 \value{
 A vector of slopes equal in length to the number simple features
@@ -24,4 +33,5 @@ Extract slopes from xyz data frame or sf objects
 \examples{
 route_xyz = lisbon_road_segment_3d
 slope_xyz(route_xyz, lonlat = FALSE)
+slope_xyz(route_xyz, lonlat = FALSE, directed = TRUE)
 }